draft-ietf-cose-rfc8152bis-struct-02.txt		draft-ietf-cose-rfc8152bis-struct-03.txt
	COSE Working Group J. Schaad		COSE Working Group J. Schaad
	Internet-Draft August Cellars		Internet-Draft August Cellars
	Obsoletes: 8152 (if approved) March 11, 2019		Obsoletes: 8152 (if approved) June 10, 2019
	Intended status: Standards Track		Intended status: Standards Track
	Expires: September 12, 2019		Expires: December 12, 2019
	CBOR CBOR Object Signing and Encryption (COSE): Structures and Process		CBOR Object Signing and Encryption (COSE): Structures and Process
	draft-ietf-cose-rfc8152bis-struct-02		draft-ietf-cose-rfc8152bis-struct-03
	Abstract		Abstract
	Concise Binary Object Representation (CBOR) is a data format designed		Concise Binary Object Representation (CBOR) is a data format designed
	for small code size and small message size. There is a need for the		for small code size and small message size. There is a need for the
	ability to have basic security services defined for this data format.		ability to have basic security services defined for this data format.
	This document defines the CBOR Object Signing and Encryption (COSE)		This document defines the CBOR Object Signing and Encryption (COSE)
	protocol. This specification describes how to create and process		protocol. This specification describes how to create and process
	signatures, message authentication codes, and encryption using CBOR		signatures, message authentication codes, and encryption using CBOR
	for serialization. This specification additionally describes how to		for serialization. This specification additionally describes how to
	skipping to change at page 1, line 49 ¶		skipping to change at page 1, line 49 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on September 12, 2019.		This Internet-Draft will expire on December 12, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 37 ¶		skipping to change at page 2, line 37 ¶
	1.5. CBOR-Related Terminology . . . . . . . . . . . . . . . . 7		1.5. CBOR-Related Terminology . . . . . . . . . . . . . . . . 7
	1.6. Document Terminology . . . . . . . . . . . . . . . . . . 8		1.6. Document Terminology . . . . . . . . . . . . . . . . . . 8
	2. Basic COSE Structure . . . . . . . . . . . . . . . . . . . . 8		2. Basic COSE Structure . . . . . . . . . . . . . . . . . . . . 8
	3. Header Parameters . . . . . . . . . . . . . . . . . . . . . . 11		3. Header Parameters . . . . . . . . . . . . . . . . . . . . . . 11
	3.1. Common COSE Headers Parameters . . . . . . . . . . . . . 13		3.1. Common COSE Headers Parameters . . . . . . . . . . . . . 13
	4. Signing Objects . . . . . . . . . . . . . . . . . . . . . . . 17		4. Signing Objects . . . . . . . . . . . . . . . . . . . . . . . 17
	4.1. Signing with One or More Signers . . . . . . . . . . . . 17		4.1. Signing with One or More Signers . . . . . . . . . . . . 17
	4.2. Signing with One Signer . . . . . . . . . . . . . . . . . 19		4.2. Signing with One Signer . . . . . . . . . . . . . . . . . 19
	4.3. Externally Supplied Data . . . . . . . . . . . . . . . . 20		4.3. Externally Supplied Data . . . . . . . . . . . . . . . . 20
	4.4. Signing and Verification Process . . . . . . . . . . . . 21		4.4. Signing and Verification Process . . . . . . . . . . . . 21
	4.5. Computing Counter Signatures . . . . . . . . . . . . . . 22		5. Counter Signatures . . . . . . . . . . . . . . . . . . . . . 22
	5. Encryption Objects . . . . . . . . . . . . . . . . . . . . . 23		5.1. Full Countersignatures . . . . . . . . . . . . . . . . . 23
	5.1. Enveloped COSE Structure . . . . . . . . . . . . . . . . 23		5.2. Abbreviated Countersignatures . . . . . . . . . . . . . . 24
	5.1.1. Content Key Distribution Methods . . . . . . . . . . 25		6. Encryption Objects . . . . . . . . . . . . . . . . . . . . . 24
	5.2. Single Recipient Encrypted . . . . . . . . . . . . . . . 25		6.1. Enveloped COSE Structure . . . . . . . . . . . . . . . . 25
	5.3. How to Encrypt and Decrypt for AEAD Algorithms . . . . . 26		6.1.1. Content Key Distribution Methods . . . . . . . . . . 26
	5.4. How to Encrypt and Decrypt for AE Algorithms . . . . . . 28		6.2. Single Recipient Encrypted . . . . . . . . . . . . . . . 27
	6. MAC Objects . . . . . . . . . . . . . . . . . . . . . . . . . 30		6.3. How to Encrypt and Decrypt for AEAD Algorithms . . . . . 28
	6.1. MACed Message with Recipients . . . . . . . . . . . . . . 30		6.4. How to Encrypt and Decrypt for AE Algorithms . . . . . . 30
	6.2. MACed Messages with Implicit Key . . . . . . . . . . . . 31		7. MAC Objects . . . . . . . . . . . . . . . . . . . . . . . . . 31
	6.3. How to Compute and Verify a MAC . . . . . . . . . . . . . 32		7.1. MACed Message with Recipients . . . . . . . . . . . . . . 32
	7. Key Objects . . . . . . . . . . . . . . . . . . . . . . . . . 33		7.2. MACed Messages with Implicit Key . . . . . . . . . . . . 33
	7.1. COSE Key Common Parameters . . . . . . . . . . . . . . . 34		7.3. How to Compute and Verify a MAC . . . . . . . . . . . . . 34
	8. Signature Algorithms . . . . . . . . . . . . . . . . . . . . 37		8. Key Objects . . . . . . . . . . . . . . . . . . . . . . . . . 35
	9. Message Authentication Code (MAC) Algorithms . . . . . . . . 38		8.1. COSE Key Common Parameters . . . . . . . . . . . . . . . 36
	10. Content Encryption Algorithms . . . . . . . . . . . . . . . . 39		9. Signature Algorithms . . . . . . . . . . . . . . . . . . . . 38
	11. Key Derivation Functions (KDFs) . . . . . . . . . . . . . . . 39		10. Message Authentication Code (MAC) Algorithms . . . . . . . . 39
	12. Content Key Distribution Methods . . . . . . . . . . . . . . 40		11. Content Encryption Algorithms . . . . . . . . . . . . . . . . 40
	12.1. Direct Encryption . . . . . . . . . . . . . . . . . . . 40		12. Key Derivation Functions (KDFs) . . . . . . . . . . . . . . . 40
	12.2. Key Wrap . . . . . . . . . . . . . . . . . . . . . . . . 41		13. Content Key Distribution Methods . . . . . . . . . . . . . . 41
	12.3. Key Transport . . . . . . . . . . . . . . . . . . . . . 41		13.1. Direct Encryption . . . . . . . . . . . . . . . . . . . 41
	12.4. Direct Key Agreement . . . . . . . . . . . . . . . . . . 42		13.2. Key Wrap . . . . . . . . . . . . . . . . . . . . . . . . 42
	12.5. Key Agreement with Key Wrap . . . . . . . . . . . . . . 43		13.3. Key Transport . . . . . . . . . . . . . . . . . . . . . 42
	13. CBOR Encoder Restrictions . . . . . . . . . . . . . . . . . . 43		13.4. Direct Key Agreement . . . . . . . . . . . . . . . . . . 43
	14. Application Profiling Considerations . . . . . . . . . . . . 44		13.5. Key Agreement with Key Wrap . . . . . . . . . . . . . . 44
	15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 45		14. CBOR Encoding Restrictions . . . . . . . . . . . . . . . . . 44
	15.1. CBOR Tag Assignment . . . . . . . . . . . . . . . . . . 45		15. Application Profiling Considerations . . . . . . . . . . . . 44
	15.2. COSE Header Parameters Registry . . . . . . . . . . . . 45		16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46
	15.3. COSE Header Algorithm Parameters Registry . . . . . . . 45		16.1. CBOR Tag Assignment . . . . . . . . . . . . . . . . . . 46
	15.4. COSE Key Common Parameters Registry . . . . . . . . . . 46		16.2. COSE Header Parameters Registry . . . . . . . . . . . . 46
	15.5. Media Type Registrations . . . . . . . . . . . . . . . . 46		16.3. COSE Header Algorithm Parameters Registry . . . . . . . 47
	15.5.1. COSE Security Message . . . . . . . . . . . . . . . 46		16.4. COSE Key Common Parameters Registry . . . . . . . . . . 47
	15.5.2. COSE Key Media Type . . . . . . . . . . . . . . . . 47		16.5. Media Type Registrations . . . . . . . . . . . . . . . . 47
	15.6. CoAP Content-Formats Registry . . . . . . . . . . . . . 49		16.5.1. COSE Security Message . . . . . . . . . . . . . . . 47
	15.7. Expert Review Instructions . . . . . . . . . . . . . . . 49		16.5.2. COSE Key Media Type . . . . . . . . . . . . . . . . 48
	16. Security Considerations . . . . . . . . . . . . . . . . . . . 50		16.6. CoAP Content-Formats Registry . . . . . . . . . . . . . 50
	17. Implementation Status . . . . . . . . . . . . . . . . . . . . 52		17. Security Considerations . . . . . . . . . . . . . . . . . . . 50
	17.1. Author's Versions . . . . . . . . . . . . . . . . . . . 52		18. Implementation Status . . . . . . . . . . . . . . . . . . . . 52
	17.2. Java Script Version . . . . . . . . . . . . . . . . . . 53		18.1. Author's Versions . . . . . . . . . . . . . . . . . . . 53
	17.3. Python Version . . . . . . . . . . . . . . . . . . . . . 54		18.2. Java Script Version . . . . . . . . . . . . . . . . . . 53
	17.4. COSE Testing Library . . . . . . . . . . . . . . . . . . 54		18.3. Python Version . . . . . . . . . . . . . . . . . . . . . 54
	18. References . . . . . . . . . . . . . . . . . . . . . . . . . 54		18.4. COSE Testing Library . . . . . . . . . . . . . . . . . . 54
	18.1. Normative References . . . . . . . . . . . . . . . . . . 54		19. References . . . . . . . . . . . . . . . . . . . . . . . . . 55
	18.2. Informative References . . . . . . . . . . . . . . . . . 56		19.1. Normative References . . . . . . . . . . . . . . . . . . 55
			19.2. Informative References . . . . . . . . . . . . . . . . . 56
	Appendix A. Guidelines for External Data Authentication of		Appendix A. Guidelines for External Data Authentication of
	Algorithms . . . . . . . . . . . . . . . . . . . . . 58		Algorithms . . . . . . . . . . . . . . . . . . . . . 58
	A.1. Algorithm Identification . . . . . . . . . . . . . . . . 58		Appendix B. Two Layers of Recipient Information . . . . . . . . 61
	A.2. Counter Signature without Headers . . . . . . . . . . . . 61		Appendix C. Examples . . . . . . . . . . . . . . . . . . . . . . 63
	Appendix B. Two Layers of Recipient Information . . . . . . . . 62		C.1. Examples of Signed Messages . . . . . . . . . . . . . . . 64
	Appendix C. Examples . . . . . . . . . . . . . . . . . . . . . . 64		C.1.1. Single Signature . . . . . . . . . . . . . . . . . . 64
	C.1. Examples of Signed Messages . . . . . . . . . . . . . . . 65		C.1.2. Multiple Signers . . . . . . . . . . . . . . . . . . 65
	C.1.1. Single Signature . . . . . . . . . . . . . . . . . . 65		C.1.3. Counter Signature . . . . . . . . . . . . . . . . . . 66
	C.1.2. Multiple Signers . . . . . . . . . . . . . . . . . . 66		C.1.4. Signature with Criticality . . . . . . . . . . . . . 67
	C.1.3. Counter Signature . . . . . . . . . . . . . . . . . . 67		C.2. Single Signer Examples . . . . . . . . . . . . . . . . . 68
	C.1.4. Signature with Criticality . . . . . . . . . . . . . 68		C.2.1. Single ECDSA Signature . . . . . . . . . . . . . . . 68
	C.2. Single Signer Examples . . . . . . . . . . . . . . . . . 69		C.3. Examples of Enveloped Messages . . . . . . . . . . . . . 69
	C.2.1. Single ECDSA Signature . . . . . . . . . . . . . . . 69		C.3.1. Direct ECDH . . . . . . . . . . . . . . . . . . . . . 69
	C.3. Examples of Enveloped Messages . . . . . . . . . . . . . 70		C.3.2. Direct Plus Key Derivation . . . . . . . . . . . . . 70
	C.3.1. Direct ECDH . . . . . . . . . . . . . . . . . . . . . 70		C.3.3. Counter Signature on Encrypted Content . . . . . . . 71
	C.3.2. Direct Plus Key Derivation . . . . . . . . . . . . . 71		C.3.4. Encrypted Content with External Data . . . . . . . . 73
	C.3.3. Counter Signature on Encrypted Content . . . . . . . 72		C.4. Examples of Encrypted Messages . . . . . . . . . . . . . 73
	C.3.4. Encrypted Content with External Data . . . . . . . . 74		C.4.1. Simple Encrypted Message . . . . . . . . . . . . . . 73
	C.4. Examples of Encrypted Messages . . . . . . . . . . . . . 74		C.4.2. Encrypted Message with a Partial IV . . . . . . . . . 74
	C.4.1. Simple Encrypted Message . . . . . . . . . . . . . . 74
	C.4.2. Encrypted Message with a Partial IV . . . . . . . . . 75		C.5. Examples of MACed Messages . . . . . . . . . . . . . . . 74
	C.5. Examples of MACed Messages . . . . . . . . . . . . . . . 75		C.5.1. Shared Secret Direct MAC . . . . . . . . . . . . . . 74
	C.5.1. Shared Secret Direct MAC . . . . . . . . . . . . . . 75		C.5.2. ECDH Direct MAC . . . . . . . . . . . . . . . . . . . 75
	C.5.2. ECDH Direct MAC . . . . . . . . . . . . . . . . . . . 76		C.5.3. Wrapped MAC . . . . . . . . . . . . . . . . . . . . . 76
	C.5.3. Wrapped MAC . . . . . . . . . . . . . . . . . . . . . 77		C.5.4. Multi-Recipient MACed Message . . . . . . . . . . . . 77
	C.5.4. Multi-Recipient MACed Message . . . . . . . . . . . . 78		C.6. Examples of MAC0 Messages . . . . . . . . . . . . . . . . 78
	C.6. Examples of MAC0 Messages . . . . . . . . . . . . . . . . 79		C.6.1. Shared Secret Direct MAC . . . . . . . . . . . . . . 78
	C.6.1. Shared Secret Direct MAC . . . . . . . . . . . . . . 79		C.7. COSE Keys . . . . . . . . . . . . . . . . . . . . . . . . 79
	C.7. COSE Keys . . . . . . . . . . . . . . . . . . . . . . . . 80		C.7.1. Public Keys . . . . . . . . . . . . . . . . . . . . . 79
	C.7.1. Public Keys . . . . . . . . . . . . . . . . . . . . . 80		C.7.2. Private Keys . . . . . . . . . . . . . . . . . . . . 80
	C.7.2. Private Keys . . . . . . . . . . . . . . . . . . . . 81		Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 82
	Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 83		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 83
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 84
	1. Introduction		1. Introduction
	There has been an increased focus on small, constrained devices that		There has been an increased focus on small, constrained devices that
	make up the Internet of Things (IoT). One of the standards that has		make up the Internet of Things (IoT). One of the standards that has
	come out of this process is "Concise Binary Object Representation		come out of this process is "Concise Binary Object Representation
	(CBOR)" [RFC7049]. CBOR extended the data model of the JavaScript		(CBOR)" [RFC7049]. CBOR extended the data model of the JavaScript
	Object Notation (JSON) [RFC8259] by allowing for binary data, among		Object Notation (JSON) [RFC8259] by allowing for binary data, among
	other changes. CBOR has been adopted by several of the IETF working		other changes. CBOR has been adopted by several of the IETF working
	groups dealing with the IoT world as their encoding of data		groups dealing with the IoT world as their encoding of data
	skipping to change at page 6, line 22 ¶		skipping to change at page 6, line 19 ¶
	directions and trimmed in others.		directions and trimmed in others.
	1.2. Changes from RFC8152		1.2. Changes from RFC8152
	o Split the orignal document into this document and		o Split the orignal document into this document and
	[I-D.ietf-cose-rfc8152bis-algs].		[I-D.ietf-cose-rfc8152bis-algs].
	o Add some text describing why there is no digest structure defined		o Add some text describing why there is no digest structure defined
	by COSE.		by COSE.
			o Rearrange the text around counter signatures and define a CBOR Tag
			for a standalong countersignature.
	1.3. Requirements Terminology		1.3. Requirements Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	1.4. CBOR Grammar		1.4. CBOR Grammar
	skipping to change at page 7, line 39 ¶		skipping to change at page 7, line 39 ¶
	//artwork[@type='CDDL']/text()		//artwork[@type='CDDL']/text()
	CDDL expects the initial non-terminal symbol to be the first symbol		CDDL expects the initial non-terminal symbol to be the first symbol
	in the file. For this reason, the first fragment of CDDL is		in the file. For this reason, the first fragment of CDDL is
	presented here.		presented here.
	start = COSE_Messages / COSE_Key / COSE_KeySet / Internal_Types		start = COSE_Messages / COSE_Key / COSE_KeySet / Internal_Types
	; This is defined to make the tool quieter:		; This is defined to make the tool quieter:
	Internal_Types = Sig_structure / Enc_structure / MAC_structure /		Internal_Types = Sig_structure / Enc_structure / MAC_structure
	COSE_KDF_Context
	The non-terminal Internal_Types is defined for dealing with the		The non-terminal Internal_Types is defined for dealing with the
	automated validation tools used during the writing of this document.		automated validation tools used during the writing of this document.
	It references those non-terminals that are used for security		It references those non-terminals that are used for security
	computations but are not emitted for transport.		computations but are not emitted for transport.
	1.5. CBOR-Related Terminology		1.5. CBOR-Related Terminology
	In JSON, maps are called objects and only have one kind of map key: a		In JSON, maps are called objects and only have one kind of map key: a
	string. In COSE, we use strings, negative integers, and unsigned		string. In COSE, we use strings, negative integers, and unsigned
	skipping to change at page 9, line 12 ¶		skipping to change at page 9, line 11 ¶
	3. The content of the message. The content is either the plaintext		3. The content of the message. The content is either the plaintext
	or the ciphertext as appropriate. The content may be detached		or the ciphertext as appropriate. The content may be detached
	(i.e. transported separately from the COSE structure), but the		(i.e. transported separately from the COSE structure), but the
	location is still used. The content is wrapped in a bstr when		location is still used. The content is wrapped in a bstr when
	present and is a nil value when detached.		present and is a nil value when detached.
	Elements after this point are dependent on the specific message type.		Elements after this point are dependent on the specific message type.
	COSE messages are built using the concept of layers to separate		COSE messages are built using the concept of layers to separate
	different types of cryptographic concepts. As an example of how this		different types of cryptographic concepts. As an example of how this
	works, consider the COSE_Encrypt message (Section 5.1). This message		works, consider the COSE_Encrypt message (Section 6.1). This message
	type is broken into two layers: the content layer and the recipient		type is broken into two layers: the content layer and the recipient
	layer. In the content layer, the plaintext is encrypted and		layer. In the content layer, the plaintext is encrypted and
	information about the encrypted message is placed. In the recipient		information about the encrypted message is placed. In the recipient
	layer, the content encryption key (CEK) is encrypted and information		layer, the content encryption key (CEK) is encrypted and information
	about how it is encrypted for each recipient is placed. A single		about how it is encrypted for each recipient is placed. A single
	layer version of the encryption message COSE_Encrypt0 (Section 5.2)		layer version of the encryption message COSE_Encrypt0 (Section 6.2)
	is provided for cases where the CEK is pre-shared.		is provided for cases where the CEK is pre-shared.
	Identification of which type of message has been presented is done by		Identification of which type of message has been presented is done by
	the following methods:		the following methods:
	1. The specific message type is known from the context. This may be		1. The specific message type is known from the context. This may be
	defined by a marker in the containing structure or by		defined by a marker in the containing structure or by
	restrictions specified by the application protocol.		restrictions specified by the application protocol.
	2. The message type is identified by a CBOR tag. Messages with a		2. The message type is identified by a CBOR tag. Messages with a
	skipping to change at page 10, line 5 ¶		skipping to change at page 10, line 5 ¶
	the untagged version of the structure is used. The value to use		the untagged version of the structure is used. The value to use
	with the parameter for each of the structures can be found in		with the parameter for each of the structures can be found in
	Table 1.		Table 1.
	4. When a COSE object is carried as a CoAP payload, the CoAP		4. When a COSE object is carried as a CoAP payload, the CoAP
	Content-Format Option can be used to identify the message		Content-Format Option can be used to identify the message
	content. The CoAP Content-Format values can be found in Table 2.		content. The CoAP Content-Format values can be found in Table 2.
	The CBOR tag for the message structure is not required as each		The CBOR tag for the message structure is not required as each
	security message is uniquely identified.		security message is uniquely identified.
	+-------+---------------+---------------+---------------------------+		+-------+------------------+----------------+-----------------------+
	| CBOR | cose-type | Data Item | Semantics |		| CBOR | cose-type | Data Item | Semantics |
	| Tag | | | |		| Tag | | | |
	+-------+---------------+---------------+---------------------------+		+-------+------------------+----------------+-----------------------+
	| 98 | cose-sign | COSE_Sign | COSE Signed Data Object |		| 98 | cose-sign | COSE_Sign | COSE Signed Data |
	| 18 | cose-sign1 | COSE_Sign1 | COSE Single Signer Data |		| | | | Object |
	| | | | Object |		| 18 | cose-sign1 | COSE_Sign1 | COSE Single Signer |
	| 96 | cose-encrypt | COSE_Encrypt | COSE Encrypted Data |		| | | | Data Object |
	| | | | Object |		| 96 | cose-encrypt | COSE_Encrypt | COSE Encrypted Data |
	| 16 | cose-encrypt0 | COSE_Encrypt0 | COSE Single Recipient |		| | | | Object |
	| | | | Encrypted Data Object |		| 16 | cose-encrypt0 | COSE_Encrypt0 | COSE Single Recipient |
	| 97 | cose-mac | COSE_Mac | COSE MACed Data Object |		| | | | Encrypted Data Object |
	| 17 | cose-mac0 | COSE_Mac0 | COSE Mac w/o Recipients |		| 97 | cose-mac | COSE_Mac | COSE MACed Data |
	| | | | Object |		| | | | Object |
	+-------+---------------+---------------+---------------------------+		| 17 | cose-mac0 | COSE_Mac0 | COSE Mac w/o |
			| | | | Recipients Object |
			| TBD0 | cose-countersign | COSE_Signature | COSE standalone |
			| | | | counter signature |
			+-------+------------------+----------------+-----------------------+
	Table 1: COSE Message Identification		Table 1: COSE Message Identification
	+--------------------------------------+----------+-----+-----------+		+--------------------------------------+----------+-----+-----------+
	| Media Type | Encoding | ID | Reference |		| Media Type | Encoding | ID | Reference |
	+--------------------------------------+----------+-----+-----------+		+--------------------------------------+----------+-----+-----------+
	| application/cose; cose-type="cose- | | 98 | [RFC8152] |		| application/cose; cose-type="cose- | | 98 | [RFC8152] |
	| sign" | | | |		| sign" | | | |
	| application/cose; cose-type="cose- | | 18 | [RFC8152] |		| application/cose; cose-type="cose- | | 18 | [RFC8152] |
	| sign1" | | | |		| sign1" | | | |
	skipping to change at page 11, line 9 ¶		skipping to change at page 11, line 9 ¶
	Table 2: CoAP Content-Formats for COSE		Table 2: CoAP Content-Formats for COSE
	The following CDDL fragment identifies all of the top messages		The following CDDL fragment identifies all of the top messages
	defined in this document. Separate non-terminals are defined for the		defined in this document. Separate non-terminals are defined for the
	tagged and the untagged versions of the messages.		tagged and the untagged versions of the messages.
	COSE_Messages = COSE_Untagged_Message / COSE_Tagged_Message		COSE_Messages = COSE_Untagged_Message / COSE_Tagged_Message
	COSE_Untagged_Message = COSE_Sign / COSE_Sign1 /		COSE_Untagged_Message = COSE_Sign / COSE_Sign1 /
	COSE_Encrypt / COSE_Encrypt0 /		COSE_Encrypt / COSE_Encrypt0 /
	COSE_Mac / COSE_Mac0		COSE_Mac / COSE_Mac0 / COSE_Countersignature
	COSE_Tagged_Message = COSE_Sign_Tagged / COSE_Sign1_Tagged /		COSE_Tagged_Message = COSE_Sign_Tagged / COSE_Sign1_Tagged /
	COSE_Encrypt_Tagged / COSE_Encrypt0_Tagged /		COSE_Encrypt_Tagged / COSE_Encrypt0_Tagged /
	COSE_Mac_Tagged / COSE_Mac0_Tagged		COSE_Mac_Tagged / COSE_Mac0_Tagged / COSE_Countersignature_Tagged
	3. Header Parameters		3. Header Parameters
	The structure of COSE has been designed to have two buckets of		The structure of COSE has been designed to have two buckets of
	information that are not considered to be part of the payload itself,		information that are not considered to be part of the payload itself,
	but are used for holding information about content, algorithms, keys,		but are used for holding information about content, algorithms, keys,
	or evaluation hints for the processing of the layer. These two		or evaluation hints for the processing of the layer. These two
	buckets are available for use in all of the structures except for		buckets are available for use in all of the structures except for
	keys. While these buckets are present, they may not all be usable in		keys. While these buckets are present, they may not all be usable in
	all instances. For example, while the protected bucket is defined as		all instances. For example, while the protected bucket is defined as
	skipping to change at page 11, line 35 ¶		skipping to change at page 11, line 35 ¶
	recipient structures do not provide for authenticated data. If this		recipient structures do not provide for authenticated data. If this
	is the case, the protected bucket is left empty.		is the case, the protected bucket is left empty.
	Both buckets are implemented as CBOR maps. The map key is a 'label'		Both buckets are implemented as CBOR maps. The map key is a 'label'
	(Section 1.5). The value portion is dependent on the definition for		(Section 1.5). The value portion is dependent on the definition for
	the label. Both maps use the same set of label/value pairs. The		the label. Both maps use the same set of label/value pairs. The
	integer and string values for labels have been divided into several		integer and string values for labels have been divided into several
	sections including a standard range, a private range, and a range		sections including a standard range, a private range, and a range
	that is dependent on the algorithm selected. The defined labels can		that is dependent on the algorithm selected. The defined labels can
	be found in the "COSE Header Parameters" IANA registry		be found in the "COSE Header Parameters" IANA registry
	(Section 15.2).		(Section 16.2).
	Two buckets are provided for each layer:		Two buckets are provided for each layer:
	protected: Contains parameters about the current layer that are		protected: Contains parameters about the current layer that are
	cryptographically protected. This bucket MUST be empty if it is		cryptographically protected. This bucket MUST be empty if it is
	not going to be included in a cryptographic computation. This		not going to be included in a cryptographic computation. This
	bucket is encoded in the message as a binary object. This value		bucket is encoded in the message as a binary object. This value
	is obtained by CBOR encoding the protected map and wrapping it in		is obtained by CBOR encoding the protected map and wrapping it in
	a bstr object. Senders SHOULD encode a zero-length map as a zero-		a bstr object. Senders SHOULD encode a zero-length map as a zero-
	length byte string rather than as a zero-length map (encoded as		length byte string rather than as a zero-length map (encoded as
	skipping to change at page 12, line 27 ¶		skipping to change at page 12, line 27 ¶
	not placed in the recipient or signature layers. In principle, one		not placed in the recipient or signature layers. In principle, one
	should be able to process any given layer without reference to any		should be able to process any given layer without reference to any
	other layer. With the exception of the COSE_Sign structure, the only		other layer. With the exception of the COSE_Sign structure, the only
	data that needs to cross layers is the cryptographic key.		data that needs to cross layers is the cryptographic key.
	The buckets are present in all of the security objects defined in		The buckets are present in all of the security objects defined in
	this document. The fields in order are the 'protected' bucket (as a		this document. The fields in order are the 'protected' bucket (as a
	CBOR 'bstr' type) and then the 'unprotected' bucket (as a CBOR 'map'		CBOR 'bstr' type) and then the 'unprotected' bucket (as a CBOR 'map'
	type). The presence of both buckets is required. The parameters		type). The presence of both buckets is required. The parameters
	that go into the buckets come from the IANA "COSE Header Parameters"		that go into the buckets come from the IANA "COSE Header Parameters"
	registry (Section 15.2). Some common parameters are defined in the		registry (Section 16.2). Some common parameters are defined in the
	next section, but a number of parameters are defined throughout this		next section.
	document.
	Labels in each of the maps MUST be unique. When processing messages,		Labels in each of the maps MUST be unique. When processing messages,
	if a label appears multiple times, the message MUST be rejected as		if a label appears multiple times, the message MUST be rejected as
	malformed. Applications SHOULD verify that the same label does not		malformed. Applications SHOULD verify that the same label does not
	occur in both the protected and unprotected headers. If the message		occur in both the protected and unprotected headers. If the message
	is not rejected as malformed, attributes MUST be obtained from the		is not rejected as malformed, attributes MUST be obtained from the
	protected bucket before they are obtained from the unprotected		protected bucket before they are obtained from the unprotected
	bucket.		bucket.
	The following CDDL fragment represents the two header buckets. A		The following CDDL fragment represents the two header buckets. A
	skipping to change at page 13, line 44 ¶		skipping to change at page 13, line 44 ¶
	crit: The parameter is used to indicate which protected header		crit: The parameter is used to indicate which protected header
	labels an application that is processing a message is required to		labels an application that is processing a message is required to
	understand. Parameters defined in this document do not need to be		understand. Parameters defined in this document do not need to be
	included as they should be understood by all implementations.		included as they should be understood by all implementations.
	When present, this parameter MUST be placed in the protected		When present, this parameter MUST be placed in the protected
	header bucket. The array MUST have at least one value in it.		header bucket. The array MUST have at least one value in it.
	Not all labels need to be included in the 'crit' parameter. The		Not all labels need to be included in the 'crit' parameter. The
	rules for deciding which header labels are placed in the array		rules for deciding which header labels are placed in the array
	are:		are:
	* Integer labels in the range of 0 to 8 SHOULD be omitted.		* Integer labels in the range of 0 to 7 SHOULD be omitted.
	* Integer labels in the range -1 to -128 can be omitted as they		* Integer labels in the range -1 to -128 can be omitted as they
	are algorithm dependent. If an application can correctly		are algorithm dependent. If an application can correctly
	process an algorithm, it can be assumed that it will correctly		process an algorithm, it can be assumed that it will correctly
	process all of the common parameters associated with that		process all of the common parameters associated with that
	algorithm. Integer labels in the range -129 to -65536 SHOULD		algorithm. Integer labels in the range -129 to -65536 SHOULD
	be included as these would be less common parameters that might		be included as these would be less common parameters that might
	not be generally supported.		not be generally supported.
	* Labels for parameters required for an application MAY be		* Labels for parameters required for an application MAY be
	skipping to change at page 15, line 24 ¶		skipping to change at page 15, line 24 ¶
	2. XOR the padded Partial IV with the context IV.		2. XOR the padded Partial IV with the context IV.
	counter signature: This parameter holds one or more counter		counter signature: This parameter holds one or more counter
	signature values. Counter signatures provide a method of having a		signature values. Counter signatures provide a method of having a
	second party sign some data. The counter signature parameter can		second party sign some data. The counter signature parameter can
	occur as an unprotected attribute in any of the following		occur as an unprotected attribute in any of the following
	structures: COSE_Sign1, COSE_Signature, COSE_Encrypt,		structures: COSE_Sign1, COSE_Signature, COSE_Encrypt,
	COSE_recipient, COSE_Encrypt0, COSE_Mac, and COSE_Mac0. These		COSE_recipient, COSE_Encrypt0, COSE_Mac, and COSE_Mac0. These
	structures all have the same beginning elements, so that a		structures all have the same beginning elements, so that a
	consistent calculation of the counter signature can be computed.		consistent calculation of the counter signature can be computed.
	Details on computing counter signatures are found in Section 4.5.		Details on counter signatures are found in Section 5.
	+-----------+-------+----------------+-------------+----------------+		+-----------+-------+----------------+-------------+----------------+
	| Name | Label | Value Type | Value | Description |		| Name | Label | Value Type | Value | Description |
	| | | | Registry | |		| | | | Registry | |
	+-----------+-------+----------------+-------------+----------------+		+-----------+-------+----------------+-------------+----------------+
	| alg | 1 | int / tstr | COSE | Cryptographic |		| alg | 1 | int / tstr | COSE | Cryptographic |
	| | | | Algorithms | algorithm to |		| | | | Algorithms | algorithm to |
	| | | | registry | use |		| | | | registry | use |
	| crit | 2 | [+ label] | COSE Header | Critical |		| crit | 2 | [+ label] | COSE Header | Critical |
	| | | | Parameters | headers to be |		| | | | Parameters | headers to be |
	skipping to change at page 18, line 31 ¶		skipping to change at page 18, line 31 ¶
	payload: This field contains the serialized content to be signed.		payload: This field contains the serialized content to be signed.
	If the payload is not present in the message, the application is		If the payload is not present in the message, the application is
	required to supply the payload separately. The payload is wrapped		required to supply the payload separately. The payload is wrapped
	in a bstr to ensure that it is transported without changes. If		in a bstr to ensure that it is transported without changes. If
	the payload is transported separately ("detached content"), then a		the payload is transported separately ("detached content"), then a
	nil CBOR object is placed in this location, and it is the		nil CBOR object is placed in this location, and it is the
	responsibility of the application to ensure that it will be		responsibility of the application to ensure that it will be
	transported without changes.		transported without changes.
	Note: When a signature with a message recovery algorithm is used		Note: When a signature with a message recovery algorithm is used
	(Section 8), the maximum number of bytes that can be recovered is		(Section 9), the maximum number of bytes that can be recovered is
	the length of the payload. The size of the payload is reduced by		the length of the payload. The size of the payload is reduced by
	the number of bytes that will be recovered. If all of the bytes		the number of bytes that will be recovered. If all of the bytes
	of the payload are consumed, then the payload is encoded as a		of the payload are consumed, then the payload is encoded as a
	zero-length binary string rather than as being absent.		zero-length binary string rather than as being absent.
	signatures: This field is an array of signatures. Each signature is		signatures: This field is an array of signatures. Each signature is
	represented as a COSE_Signature structure.		represented as a COSE_Signature structure.
	The CDDL fragment that represents the above text for COSE_Sign		The CDDL fragment that represents the above text for COSE_Sign
	follows.		follows.
	skipping to change at page 21, line 26 ¶		skipping to change at page 21, line 26 ¶
	1. A text string identifying the context of the signature. The		1. A text string identifying the context of the signature. The
	context string is:		context string is:
	"Signature" for signatures using the COSE_Signature structure.		"Signature" for signatures using the COSE_Signature structure.
	"Signature1" for signatures using the COSE_Sign1 structure.		"Signature1" for signatures using the COSE_Sign1 structure.
	"CounterSignature" for signatures used as counter signature		"CounterSignature" for signatures used as counter signature
	attributes.		attributes.
			"CounterSignature0" for signatures used as CounterSignature0
			attributes.
	2. The protected attributes from the body structure encoded in a		2. The protected attributes from the body structure encoded in a
	bstr type. If there are no protected attributes, a bstr of		bstr type. If there are no protected attributes, a bstr of
	length zero is used.		length zero is used.
	3. The protected attributes from the signer structure encoded in a		3. The protected attributes from the signer structure encoded in a
	bstr type. If there are no protected attributes, a bstr of		bstr type. If there are no protected attributes, a bstr of
	length zero is used. This field is omitted for the COSE_Sign1		length zero is used. This field is omitted for the COSE_Sign1
	signature structure.		signature structure and CounterSignature0 attributes.
	4. The protected attributes from the application encoded in a bstr		4. The protected attributes from the application encoded in a bstr
	type. If this field is not supplied, it defaults to a zero-		type. If this field is not supplied, it defaults to a zero-
	length binary string. (See Section 4.3 for application guidance		length binary string. (See Section 4.3 for application guidance
	on constructing this field.)		on constructing this field.)
	5. The payload to be signed encoded in a bstr type. The payload is		5. The payload to be signed encoded in a bstr type. The payload is
	placed here independent of how it is transported.		placed here independent of how it is transported.
	The CDDL fragment that describes the above text is:		The CDDL fragment that describes the above text is:
	skipping to change at page 22, line 4 ¶		skipping to change at page 22, line 12 ¶
	The CDDL fragment that describes the above text is:		The CDDL fragment that describes the above text is:
	Sig_structure = [		Sig_structure = [
	context : "Signature" / "Signature1" / "CounterSignature",		context : "Signature" / "Signature1" / "CounterSignature",
	body_protected : empty_or_serialized_map,		body_protected : empty_or_serialized_map,
	? sign_protected : empty_or_serialized_map,		? sign_protected : empty_or_serialized_map,
	external_aad : bstr,		external_aad : bstr,
	payload : bstr		payload : bstr
	]		]
	How to compute a signature:		How to compute a signature:
	1. Create a Sig_structure and populate it with the appropriate		1. Create a Sig_structure and populate it with the appropriate
	fields.		fields.
	2. Create the value ToBeSigned by encoding the Sig_structure to a		2. Create the value ToBeSigned by encoding the Sig_structure to a
	byte string, using the encoding described in Section 13.		byte string, using the encoding described in Section 14.
	3. Call the signature creation algorithm passing in K (the key to		3. Call the signature creation algorithm passing in K (the key to
	sign with), alg (the algorithm to sign with), and ToBeSigned (the		sign with), alg (the algorithm to sign with), and ToBeSigned (the
	value to sign).		value to sign).
	4. Place the resulting signature value in the 'signature' field of		4. Place the resulting signature value in the 'signature' field of
	the array.		the array.
	The steps for verifying a signature are:		The steps for verifying a signature are:
	1. Create a Sig_structure object and populate it with the		1. Create a Sig_structure object and populate it with the
	appropriate fields.		appropriate fields.
	2. Create the value ToBeSigned by encoding the Sig_structure to a		2. Create the value ToBeSigned by encoding the Sig_structure to a
	byte string, using the encoding described in Section 13.		byte string, using the encoding described in Section 14.
	3. Call the signature verification algorithm passing in K (the key		3. Call the signature verification algorithm passing in K (the key
	to verify with), alg (the algorithm used sign with), ToBeSigned		to verify with), alg (the algorithm used sign with), ToBeSigned
	(the value to sign), and sig (the signature to be verified).		(the value to sign), and sig (the signature to be verified).
	In addition to performing the signature verification, the application		In addition to performing the signature verification, the application
	performs the appropriate checks to ensure that the key is correctly		performs the appropriate checks to ensure that the key is correctly
	paired with the signing identity and that the signing identity is		paired with the signing identity and that the signing identity is
	authorized before performing actions.		authorized before performing actions.
	4.5. Computing Counter Signatures		5. Counter Signatures
	Counter signatures provide a method of associating a different		COSE supports two different forms for counter signatures. Full
	signature generated by different signers with some piece of content.		countersignatures use the structure COSE_Countersign. This is same
	This is normally used to provide a signature on a signature allowing		structure as COSE_Signature and thus it can have protected
	for a proof that a signature existed at a given time (e.g., a		attributes, chained countersignatures and information about
	Timestamp). In this document, we allow for counter signatures to		identifying the key. Abbreviated countersignatures use the structure
	exist in a greater number of environments. As an example, it is		COSE_Countersign1. This structure only contains the signature value
	possible to place a counter signature in the unprotected attributes		and nothing else. The structures cannot be converted between each
	of a COSE_Encrypt object. This would allow for an intermediary to		other; as the signature computation includes a parameter identifying
	either verify that the encrypted byte string has not been modified,		which structure is being used, the converted structure will fail
	without being able to decrypt it, or assert that an encrypted byte		signature validation.
	string either existed at a given time or passed through it in terms
	of routing (e.g., a proxy signature).		COSE was designed for uniformity in how the data strutures are
			specified. One result of this is that for COSE one can expand the
			concept of countersignatures beyond just the idea of signing a
			signature to being able to sign most of the structures without having
			to create a new signing layer. When creating a countersignature, one
			needs to be clear about the security properties that result. When
			done on a COSE_Signature, the normal countersignature semantics are
			preserved. That is the countersignature makes a statement about the
			existance of a signature and, when used as a timestamp, a time point
			at which the signature exists. When done on a COSE_Mac or a
			COSE_Mac0, one effectively upgrades the MAC operation to a sginature
			operation. When done on a COSE_Encrypt or COSE_Encrypt0, the
			existance of the encrypted data is attested to. It should be noted
			that there is a big difference between attesting to the enrypted data
			as oppose to attesting to the unencrypted data. If the latter is
			what is desired, then one needs to apply a signature to the data and
			then encrypt that. It is always possible to construct cases where
			the decryption is successful, while providing completely different
			answers by using a different key. This situation is not detectable
			by a countersignature on the encrypted data.
			5.1. Full Countersignatures
			The COSE_Countersignature structure allows for the same set of
			capabilities of a COSE_Signature. This means that all of the
			capabilities of a signature are duplicated with this structure.
			Specifically, the countersigner does not need to be related to the
			producer of what is being counter signed as key and algorithm
			identification can be placed in the countersignature attributes.
			This also means that the countersignature can itself be
			countersigned. This is a feature required by protocols such as long-
			term archiving services. More information on how this is used can be
			found in the evidence record syntax described in [RFC4998].
			The full countersignature structure can be encoded as either a tagged
			or untagged depending on the context it is used in. A tagged
			COSE_Countersign steruture is identified byt the CBOR tag TBD0. The
			CDDL fragment for full countersignatures is:
			COSE_CounterSignature_Tagged = #6.98(COSE_CounterSignature)
			COSE_CounterSignature = COSE_Signature
			The details of the fields of a countersignature can be found in
			Section 4.1. The process of creating and validating abbreviated
			countersignatures is defined in Section 4.4.
	An example of a counter signature on a signature can be found in		An example of a counter signature on a signature can be found in
	Appendix C.1.3. An example of a counter signature in an encryption		Appendix C.1.3. An example of a counter signature in an encryption
	object can be found in Appendix C.3.3.		object can be found in Appendix C.3.3.
	The creation and validation of counter signatures over the different
	items relies on the fact that the objects have the same structure.
	The elements are a set of protected attributes, a set of unprotected
	attributes, and a body, in that order. This means that the
	Sig_structure can be used in a uniform manner to get the byte string
	for processing a signature. If the counter signature is going to be
	computed over a COSE_Encrypt structure, the body_protected and
	payload items can be mapped into the Sig_structure in the same manner
	as from the COSE_Sign structure.
	It should be noted that only a signature algorithm with appendix (see		It should be noted that only a signature algorithm with appendix (see
	Section 8) can be used for counter signatures. This is because the		Section 9) can be used for counter signatures. This is because the
	body should be able to be processed without having to evaluate the		body should be able to be processed without having to evaluate the
	counter signature, and this is not possible for signature schemes		counter signature, and this is not possible for signature schemes
	with message recovery.		with message recovery.
	5. Encryption Objects		5.2. Abbreviated Countersignatures
			Abbreviated countersignatures were designed primarily to deal with
			the problem of having group encrypted messaging, but still needing to
			know who orginated the message. The object was to keep the
			countersignature as small as possible while still providing the
			needed security. For abbreviated countersignatures, there is no
			provision for any protected attributes related to the signing
			operation. Instead, the context that was used to describe the
			encryption processing is also assumed to describe the context that
			was used to create the countersignature.
			The byte string representing the signature value is placed in the
			CounterSignature0 attribute. This attribute is then encoded as an
			unprotected header. The attribute is defined below.
			The process of creating and validating abbreviated countersignatures
			is defined in Section 4.4.
			+-------------------+-------+---------+-------+---------------------+
			| Name | Label | Value | Value | Description |
			| | | Type | | |
			+-------------------+-------+---------+-------+---------------------+
			| CounterSignature0 | 9 | bstr | | Abbreviated |
			| | | | | Countersignature |
			+-------------------+-------+---------+-------+---------------------+
			Table 4: Header Parameter for CounterSignature0
			6. Encryption Objects
	COSE supports two different encryption structures. COSE_Encrypt0 is		COSE supports two different encryption structures. COSE_Encrypt0 is
	used when a recipient structure is not needed because the key to be		used when a recipient structure is not needed because the key to be
	used is known implicitly. COSE_Encrypt is used the rest of the time.		used is known implicitly. COSE_Encrypt is used the rest of the time.
	This includes cases where there are multiple recipients or a		This includes cases where there are multiple recipients or a
	recipient algorithm other than direct (i.e. pre-shared secret) is		recipient algorithm other than direct (i.e. pre-shared secret) is
	used.		used.
	5.1. Enveloped COSE Structure		6.1. Enveloped COSE Structure
	The enveloped structure allows for one or more recipients of a		The enveloped structure allows for one or more recipients of a
	message. There are provisions for parameters about the content and		message. There are provisions for parameters about the content and
	parameters about the recipient information to be carried in the		parameters about the recipient information to be carried in the
	message. The protected parameters associated with the content are		message. The protected parameters associated with the content are
	authenticated by the content encryption algorithm. The protected		authenticated by the content encryption algorithm. The protected
	parameters associated with the recipient are authenticated by the		parameters associated with the recipient are authenticated by the
	recipient algorithm (when the algorithm supports it). Examples of		recipient algorithm (when the algorithm supports it). Examples of
	parameters about the content are the type of the content and the		parameters about the content are the type of the content and the
	content encryption algorithm. Examples of parameters about the		content encryption algorithm. Examples of parameters about the
	skipping to change at page 25, line 20 ¶		skipping to change at page 26, line 44 ¶
	The CDDL fragment that corresponds to the above text for		The CDDL fragment that corresponds to the above text for
	COSE_recipient is:		COSE_recipient is:
	COSE_recipient = [		COSE_recipient = [
	Headers,		Headers,
	ciphertext : bstr / nil,		ciphertext : bstr / nil,
	? recipients : [+COSE_recipient]		? recipients : [+COSE_recipient]
	]		]
	5.1.1. Content Key Distribution Methods		6.1.1. Content Key Distribution Methods
	An encrypted message consists of an encrypted content and an		An encrypted message consists of an encrypted content and an
	encrypted CEK for one or more recipients. The CEK is encrypted for		encrypted CEK for one or more recipients. The CEK is encrypted for
	each recipient, using a key specific to that recipient. The details		each recipient, using a key specific to that recipient. The details
	of this encryption depend on which class the recipient algorithm		of this encryption depend on which class the recipient algorithm
	falls into. Specific details on each of the classes can be found in		falls into. Specific details on each of the classes can be found in
	Section 12. A short summary of the five content key distribution		Section 13. A short summary of the five content key distribution
	methods is:		methods is:
	direct: The CEK is the same as the identified previously distributed		direct: The CEK is the same as the identified previously distributed
	symmetric key or is derived from a previously distributed secret.		symmetric key or is derived from a previously distributed secret.
	No CEK is transported in the message.		No CEK is transported in the message.
	symmetric key-encryption keys (KEK): The CEK is encrypted using a		symmetric key-encryption keys (KEK): The CEK is encrypted using a
	previously distributed symmetric KEK. Also known as key wrap.		previously distributed symmetric KEK. Also known as key wrap.
	key agreement: The recipient's public key and a sender's private key		key agreement: The recipient's public key and a sender's private key
	are used to generate a pairwise secret, a Key Derivation Function		are used to generate a pairwise secret, a Key Derivation Function
	(KDF) is applied to derive a key, and then the CEK is either the		(KDF) is applied to derive a key, and then the CEK is either the
	derived key or encrypted by the derived key.		derived key or encrypted by the derived key.
	key transport: The CEK is encrypted with the recipient's public key.		key transport: The CEK is encrypted with the recipient's public key.
	No key transport algorithms are defined in this document.		No key transport algorithms are defined in this document.
	passwords: The CEK is encrypted in a KEK that is derived from a		passwords: The CEK is encrypted in a KEK that is derived from a
	password. No password algorithms are defined in this document.		password. No password algorithms are defined in this document.
	5.2. Single Recipient Encrypted		6.2. Single Recipient Encrypted
	The COSE_Encrypt0 encrypted structure does not have the ability to		The COSE_Encrypt0 encrypted structure does not have the ability to
	specify recipients of the message. The structure assumes that the		specify recipients of the message. The structure assumes that the
	recipient of the object will already know the identity of the key to		recipient of the object will already know the identity of the key to
	be used in order to decrypt the message. If a key needs to be		be used in order to decrypt the message. If a key needs to be
	identified to the recipient, the enveloped structure ought to be		identified to the recipient, the enveloped structure ought to be
	used.		used.
	Examples of encrypted messages can be found in Appendix C.3.		Examples of encrypted messages can be found in Appendix C.3.
	skipping to change at page 26, line 24 ¶		skipping to change at page 27, line 48 ¶
	COSE_Encrypt0_Tagged = #6.16(COSE_Encrypt0)		COSE_Encrypt0_Tagged = #6.16(COSE_Encrypt0)
	The COSE_Encrypt0 structure is a CBOR array. The fields of the array		The COSE_Encrypt0 structure is a CBOR array. The fields of the array
	in order are:		in order are:
	protected: This is as described in Section 3.		protected: This is as described in Section 3.
	unprotected: This is as described in Section 3.		unprotected: This is as described in Section 3.
	ciphertext: This is as described in Section 5.1.		ciphertext: This is as described in Section 6.1.
	The CDDL fragment for COSE_Encrypt0 that corresponds to the above		The CDDL fragment for COSE_Encrypt0 that corresponds to the above
	text is:		text is:
	COSE_Encrypt0 = [		COSE_Encrypt0 = [
	Headers,		Headers,
	ciphertext : bstr / nil,		ciphertext : bstr / nil,
	]		]
	5.3. How to Encrypt and Decrypt for AEAD Algorithms		6.3. How to Encrypt and Decrypt for AEAD Algorithms
	The encryption algorithm for AEAD algorithms is fairly simple. The		The encryption algorithm for AEAD algorithms is fairly simple. The
	first step is to create a consistent byte string for the		first step is to create a consistent byte string for the
	authenticated data structure. For this purpose, we use an		authenticated data structure. For this purpose, we use an
	Enc_structure. The Enc_structure is a CBOR array. The fields of the		Enc_structure. The Enc_structure is a CBOR array. The fields of the
	Enc_structure in order are:		Enc_structure in order are:
	1. A text string identifying the context of the authenticated data		1. A text string identifying the context of the authenticated data
	structure. The context string is:		structure. The context string is:
	skipping to change at page 27, line 31 ¶		skipping to change at page 29, line 4 ¶
	constructing this field.)		constructing this field.)
	The CDDL fragment that describes the above text is:		The CDDL fragment that describes the above text is:
	Enc_structure = [		Enc_structure = [
	context : "Encrypt" / "Encrypt0" / "Enc_Recipient" /		context : "Encrypt" / "Encrypt0" / "Enc_Recipient" /
	"Mac_Recipient" / "Rec_Recipient",		"Mac_Recipient" / "Rec_Recipient",
	protected : empty_or_serialized_map,		protected : empty_or_serialized_map,
	external_aad : bstr		external_aad : bstr
	]		]
	How to encrypt a message:		How to encrypt a message:
	1. Create an Enc_structure and populate it with the appropriate		1. Create an Enc_structure and populate it with the appropriate
	fields.		fields.
	2. Encode the Enc_structure to a byte string (Additional		2. Encode the Enc_structure to a byte string (Additional
	Authenticated Data (AAD)), using the encoding described in		Authenticated Data (AAD)), using the encoding described in
	Section 13.		Section 14.
	3. Determine the encryption key (K). This step is dependent on the		3. Determine the encryption key (K). This step is dependent on the
	class of recipient algorithm being used. For:		class of recipient algorithm being used. For:
	No Recipients: The key to be used is determined by the algorithm		No Recipients: The key to be used is determined by the algorithm
	and key at the current layer. Examples are key transport keys		and key at the current layer. Examples are key transport keys
	(Section 12.3), key wrap keys (Section 12.2), or pre-shared		(Section 13.3), key wrap keys (Section 13.2), or pre-shared
	secrets.		secrets.
	Direct Encryption and Direct Key Agreement: The key is		Direct Encryption and Direct Key Agreement: The key is
	determined by the key and algorithm in the recipient		determined by the key and algorithm in the recipient
	structure. The encryption algorithm and size of the key to be		structure. The encryption algorithm and size of the key to be
	used are inputs into the KDF used for the recipient. (For		used are inputs into the KDF used for the recipient. (For
	direct, the KDF can be thought of as the identity operation.)		direct, the KDF can be thought of as the identity operation.)
	Examples of these algorithms are found in Sections !!! DIRECT-		Examples of these algorithms are found in Sections 6.1.2 and
	KDF !!! and !!! ECDH !!! of [I-D.ietf-cose-rfc8152bis-algs].		6.3 of [I-D.ietf-cose-rfc8152bis-algs].
	Other: The key is randomly or pseudorandomly generated.		Other: The key is randomly or pseudorandomly generated.
	4. Call the encryption algorithm with K (the encryption key), P (the		4. Call the encryption algorithm with K (the encryption key), P (the
	plaintext), and AAD. Place the returned ciphertext into the		plaintext), and AAD. Place the returned ciphertext into the
	'ciphertext' field of the structure.		'ciphertext' field of the structure.
	5. For recipients of the message, recursively perform the encryption		5. For recipients of the message, recursively perform the encryption
	algorithm for that recipient, using K (the encryption key) as the		algorithm for that recipient, using K (the encryption key) as the
	plaintext.		plaintext.
	How to decrypt a message:		How to decrypt a message:
	1. Create an Enc_structure and populate it with the appropriate		1. Create an Enc_structure and populate it with the appropriate
	fields.		fields.
	2. Encode the Enc_structure to a byte string (AAD), using the		2. Encode the Enc_structure to a byte string (AAD), using the
	encoding described in Section 13.		encoding described in Section 14.
	3. Determine the decryption key. This step is dependent on the		3. Determine the decryption key. This step is dependent on the
	class of recipient algorithm being used. For:		class of recipient algorithm being used. For:
	No Recipients: The key to be used is determined by the algorithm		No Recipients: The key to be used is determined by the algorithm
	and key at the current layer. Examples are key transport keys		and key at the current layer. Examples are key transport keys
	(Section 12.3), key wrap keys (Section 12.2), or pre-shared		(Section 13.3), key wrap keys (Section 13.2), or pre-shared
	secrets.		secrets.
	Direct Encryption and Direct Key Agreement: The key is		Direct Encryption and Direct Key Agreement: The key is
	determined by the key and algorithm in the recipient		determined by the key and algorithm in the recipient
	structure. The encryption algorithm and size of the key to be		structure. The encryption algorithm and size of the key to be
	used are inputs into the KDF used for the recipient. (For		used are inputs into the KDF used for the recipient. (For
	direct, the KDF can be thought of as the identity operation.)		direct, the KDF can be thought of as the identity operation.)
	Other: The key is determined by decoding and decrypting one of		Other: The key is determined by decoding and decrypting one of
	the recipient structures.		the recipient structures.
	4. Call the decryption algorithm with K (the decryption key to use),		4. Call the decryption algorithm with K (the decryption key to use),
	C (the ciphertext), and AAD.		C (the ciphertext), and AAD.
	5.4. How to Encrypt and Decrypt for AE Algorithms		6.4. How to Encrypt and Decrypt for AE Algorithms
	How to encrypt a message:		How to encrypt a message:
	1. Verify that the 'protected' field is empty.		1. Verify that the 'protected' field is empty.
	2. Verify that there was no external additional authenticated data		2. Verify that there was no external additional authenticated data
	supplied for this operation.		supplied for this operation.
	3. Determine the encryption key. This step is dependent on the		3. Determine the encryption key. This step is dependent on the
	class of recipient algorithm being used. For:		class of recipient algorithm being used. For:
	No Recipients: The key to be used is determined by the algorithm		No Recipients: The key to be used is determined by the algorithm
	and key at the current layer. Examples are key transport keys		and key at the current layer. Examples are key transport keys
	(Section 12.3), key wrap keys (Section 12.2), or pre-shared		(Section 13.3), key wrap keys (Section 13.2), or pre-shared
	secrets.		secrets.
	Direct Encryption and Direct Key Agreement: The key is		Direct Encryption and Direct Key Agreement: The key is
	determined by the key and algorithm in the recipient		determined by the key and algorithm in the recipient
	structure. The encryption algorithm and size of the key to be		structure. The encryption algorithm and size of the key to be
	used are inputs into the KDF used for the recipient. (For		used are inputs into the KDF used for the recipient. (For
	direct, the KDF can be thought of as the identity operation.)		direct, the KDF can be thought of as the identity operation.)
	Examples of these algorithms are found in Sections !!!DIRECT-		Examples of these algorithms are found in Sections 6.1.2 and
	KDF!!! and !!! ECDH !!! .		6.3 of [I-D.ietf-cose-rfc8152bis-algs].
	Other: The key is randomly generated.		Other: The key is randomly generated.
	4. Call the encryption algorithm with K (the encryption key to use)		4. Call the encryption algorithm with K (the encryption key to use)
	and P (the plaintext). Place the returned ciphertext into the		and P (the plaintext). Place the returned ciphertext into the
	'ciphertext' field of the structure.		'ciphertext' field of the structure.
	5. For recipients of the message, recursively perform the encryption		5. For recipients of the message, recursively perform the encryption
	algorithm for that recipient, using K (the encryption key) as the		algorithm for that recipient, using K (the encryption key) as the
	plaintext.		plaintext.
	skipping to change at page 29, line 46 ¶		skipping to change at page 31, line 21 ¶
	1. Verify that the 'protected' field is empty.		1. Verify that the 'protected' field is empty.
	2. Verify that there was no external additional authenticated data		2. Verify that there was no external additional authenticated data
	supplied for this operation.		supplied for this operation.
	3. Determine the decryption key. This step is dependent on the		3. Determine the decryption key. This step is dependent on the
	class of recipient algorithm being used. For:		class of recipient algorithm being used. For:
	No Recipients: The key to be used is determined by the algorithm		No Recipients: The key to be used is determined by the algorithm
	and key at the current layer. Examples are key transport keys		and key at the current layer. Examples are key transport keys
	(Section 12.3), key wrap keys (Section 12.2), or pre-shared		(Section 13.3), key wrap keys (Section 13.2), or pre-shared
	secrets.		secrets.
	Direct Encryption and Direct Key Agreement: The key is		Direct Encryption and Direct Key Agreement: The key is
	determined by the key and algorithm in the recipient		determined by the key and algorithm in the recipient
	structure. The encryption algorithm and size of the key to be		structure. The encryption algorithm and size of the key to be
	used are inputs into the KDF used for the recipient. (For		used are inputs into the KDF used for the recipient. (For
	direct, the KDF can be thought of as the identity operation.)		direct, the KDF can be thought of as the identity operation.)
	Examples of these algorithms are found in Sections !!! DIRECT-		Examples of these algorithms are found in Sections 6.1.2 and
	KDF !!! and !!! ECDH !!! .		6.3 of [I-D.ietf-cose-rfc8152bis-algs].
	Other: The key is determined by decoding and decrypting one of		Other: The key is determined by decoding and decrypting one of
	the recipient structures.		the recipient structures.
	4. Call the decryption algorithm with K (the decryption key to use)		4. Call the decryption algorithm with K (the decryption key to use)
	and C (the ciphertext).		and C (the ciphertext).
	6. MAC Objects		7. MAC Objects
	COSE supports two different MAC structures. COSE_MAC0 is used when a		COSE supports two different MAC structures. COSE_MAC0 is used when a
	recipient structure is not needed because the key to be used is		recipient structure is not needed because the key to be used is
	implicitly known. COSE_MAC is used for all other cases. These		implicitly known. COSE_MAC is used for all other cases. These
	include a requirement for multiple recipients, the key being unknown,		include a requirement for multiple recipients, the key being unknown,
	and a recipient algorithm of other than direct.		and a recipient algorithm of other than direct.
	In this section, we describe the structure and methods to be used		In this section, we describe the structure and methods to be used
	when doing MAC authentication in COSE. This document allows for the		when doing MAC authentication in COSE. This document allows for the
	use of all of the same classes of recipient algorithms as are allowed		use of all of the same classes of recipient algorithms as are allowed
	skipping to change at page 30, line 41 ¶		skipping to change at page 32, line 16 ¶
	the content has not been changed since the MAC was computed and to		the content has not been changed since the MAC was computed and to
	use the recipient algorithm to verify who sent it. The classes of		use the recipient algorithm to verify who sent it. The classes of
	recipient algorithms that support this are those that use a pre-		recipient algorithms that support this are those that use a pre-
	shared secret or do static-static (SS) key agreement (without the key		shared secret or do static-static (SS) key agreement (without the key
	wrap step). In both of these cases, the entity that created and sent		wrap step). In both of these cases, the entity that created and sent
	the message MAC can be validated. (This knowledge of the sender		the message MAC can be validated. (This knowledge of the sender
	assumes that there are only two parties involved and that you did not		assumes that there are only two parties involved and that you did not
	send the message to yourself.) The origination property can be		send the message to yourself.) The origination property can be
	obtained with both of the MAC message structures.		obtained with both of the MAC message structures.
	6.1. MACed Message with Recipients		7.1. MACed Message with Recipients
	The multiple recipient MACed message uses two structures: the		The multiple recipient MACed message uses two structures: the
	COSE_Mac structure defined in this section for carrying the body and		COSE_Mac structure defined in this section for carrying the body and
	the COSE_recipient structure (Section 5.1) to hold the key used for		the COSE_recipient structure (Section 6.1) to hold the key used for
	the MAC computation. Examples of MACed messages can be found in		the MAC computation. Examples of MACed messages can be found in
	Appendix C.5.		Appendix C.5.
	The MAC structure can be encoded as either tagged or untagged		The MAC structure can be encoded as either tagged or untagged
	depending on the context it will be used in. A tagged COSE_Mac		depending on the context it will be used in. A tagged COSE_Mac
	structure is identified by the CBOR tag 97. The CDDL fragment that		structure is identified by the CBOR tag 97. The CDDL fragment that
	represents this is:		represents this is:
	COSE_Mac_Tagged = #6.97(COSE_Mac)		COSE_Mac_Tagged = #6.97(COSE_Mac)
	skipping to change at page 31, line 27 ¶		skipping to change at page 32, line 49 ¶
	the payload is not present in the message, the application is		the payload is not present in the message, the application is
	required to supply the payload separately. The payload is wrapped		required to supply the payload separately. The payload is wrapped
	in a bstr to ensure that it is transported without changes. If		in a bstr to ensure that it is transported without changes. If
	the payload is transported separately (i.e., detached content),		the payload is transported separately (i.e., detached content),
	then a nil CBOR value is placed in this location, and it is the		then a nil CBOR value is placed in this location, and it is the
	responsibility of the application to ensure that it will be		responsibility of the application to ensure that it will be
	transported without changes.		transported without changes.
	tag: This field contains the MAC value.		tag: This field contains the MAC value.
	recipients: This is as described in Section 5.1.		recipients: This is as described in Section 6.1.
	The CDDL fragment that represents the above text for COSE_Mac		The CDDL fragment that represents the above text for COSE_Mac
	follows.		follows.
	COSE_Mac = [		COSE_Mac = [
	Headers,		Headers,
	payload : bstr / nil,		payload : bstr / nil,
	tag : bstr,		tag : bstr,
	recipients :[+COSE_recipient]		recipients :[+COSE_recipient]
	]		]
	6.2. MACed Messages with Implicit Key		7.2. MACed Messages with Implicit Key
	In this section, we describe the structure and methods to be used		In this section, we describe the structure and methods to be used
	when doing MAC authentication for those cases where the recipient is		when doing MAC authentication for those cases where the recipient is
	implicitly known.		implicitly known.
	The MACed message uses the COSE_Mac0 structure defined in this		The MACed message uses the COSE_Mac0 structure defined in this
	section for carrying the body. Examples of MACed messages with an		section for carrying the body. Examples of MACed messages with an
	implicit key can be found in Appendix C.6.		implicit key can be found in Appendix C.6.
	The MAC structure can be encoded as either tagged or untagged		The MAC structure can be encoded as either tagged or untagged
	skipping to change at page 32, line 16 ¶		skipping to change at page 33, line 39 ¶
	COSE_Mac0_Tagged = #6.17(COSE_Mac0)		COSE_Mac0_Tagged = #6.17(COSE_Mac0)
	The COSE_Mac0 structure is a CBOR array. The fields of the array in		The COSE_Mac0 structure is a CBOR array. The fields of the array in
	order are:		order are:
	protected: This is as described in Section 3.		protected: This is as described in Section 3.
	unprotected: This is as described in Section 3.		unprotected: This is as described in Section 3.
	payload: This is as described in Section 6.1.		payload: This is as described in Section 7.1.
	tag: This field contains the MAC value.		tag: This field contains the MAC value.
	The CDDL fragment that corresponds to the above text is:		The CDDL fragment that corresponds to the above text is:
	COSE_Mac0 = [		COSE_Mac0 = [
	Headers,		Headers,
	payload : bstr / nil,		payload : bstr / nil,
	tag : bstr,		tag : bstr,
	]		]
	6.3. How to Compute and Verify a MAC		7.3. How to Compute and Verify a MAC
	In order to get a consistent encoding of the data to be		In order to get a consistent encoding of the data to be
	authenticated, the MAC_structure is used to have a canonical form.		authenticated, the MAC_structure is used to have a canonical form.
	The MAC_structure is a CBOR array. The fields of the MAC_structure		The MAC_structure is a CBOR array. The fields of the MAC_structure
	in order are:		in order are:
	1. A text string that identifies the structure that is being		1. A text string that identifies the structure that is being
	encoded. This string is "MAC" for the COSE_Mac structure. This		encoded. This string is "MAC" for the COSE_Mac structure. This
	string is "MAC0" for the COSE_Mac0 structure.		string is "MAC0" for the COSE_Mac0 structure.
	skipping to change at page 33, line 18 ¶		skipping to change at page 34, line 42 ¶
	external_aad : bstr,		external_aad : bstr,
	payload : bstr		payload : bstr
	]		]
	The steps to compute a MAC are:		The steps to compute a MAC are:
	1. Create a MAC_structure and populate it with the appropriate		1. Create a MAC_structure and populate it with the appropriate
	fields.		fields.
	2. Create the value ToBeMaced by encoding the MAC_structure to a		2. Create the value ToBeMaced by encoding the MAC_structure to a
	byte string, using the encoding described in Section 13.		byte string, using the encoding described in Section 14.
	3. Call the MAC creation algorithm passing in K (the key to use),		3. Call the MAC creation algorithm passing in K (the key to use),
	alg (the algorithm to MAC with), and ToBeMaced (the value to		alg (the algorithm to MAC with), and ToBeMaced (the value to
	compute the MAC on).		compute the MAC on).
	4. Place the resulting MAC in the 'tag' field of the COSE_Mac or		4. Place the resulting MAC in the 'tag' field of the COSE_Mac or
	COSE_Mac0 structure.		COSE_Mac0 structure.
	5. For COSE_Mac structures, encrypt and encode the MAC key for each		5. For COSE_Mac structures, encrypt and encode the MAC key for each
	recipient of the message.		recipient of the message.
	The steps to verify a MAC are:		The steps to verify a MAC are:
	1. Create a MAC_structure object and populate it with the		1. Create a MAC_structure object and populate it with the
	appropriate fields.		appropriate fields.
	2. Create the value ToBeMaced by encoding the MAC_structure to a		2. Create the value ToBeMaced by encoding the MAC_structure to a
	byte string, using the encoding described in Section 13.		byte string, using the encoding described in Section 14.
	3. For COSE_Mac structures, obtain the cryptographic key from one of		3. For COSE_Mac structures, obtain the cryptographic key from one of
	the recipients of the message.		the recipients of the message.
	4. Call the MAC creation algorithm passing in K (the key to use),		4. Call the MAC creation algorithm passing in K (the key to use),
	alg (the algorithm to MAC with), and ToBeMaced (the value to		alg (the algorithm to MAC with), and ToBeMaced (the value to
	compute the MAC on).		compute the MAC on).
	5. Compare the MAC value to the 'tag' field of the COSE_Mac or		5. Compare the MAC value to the 'tag' field of the COSE_Mac or
	COSE_Mac0 structure.		COSE_Mac0 structure.
	7. Key Objects		8. Key Objects
	A COSE Key structure is built on a CBOR map object. The set of		A COSE Key structure is built on a CBOR map object. The set of
	common parameters that can appear in a COSE Key can be found in the		common parameters that can appear in a COSE Key can be found in the
	IANA "COSE Key Common Parameters" registry (Section 15.4).		IANA "COSE Key Common Parameters" registry (Section 16.4).
	Additional parameters defined for specific key types can be found in		Additional parameters defined for specific key types can be found in
	the IANA "COSE Key Type Parameters" registry ([COSE.KeyParameters]).		the IANA "COSE Key Type Parameters" registry ([COSE.KeyParameters]).
	A COSE Key Set uses a CBOR array object as its underlying type. The		A COSE Key Set uses a CBOR array object as its underlying type. The
	values of the array elements are COSE Keys. A COSE Key Set MUST have		values of the array elements are COSE Keys. A COSE Key Set MUST have
	at least one element in the array. Examples of COSE Key Sets can be		at least one element in the array. Examples of COSE Key Sets can be
	found in Appendix C.7.		found in Appendix C.7.
	Each element in a COSE Key Set MUST be processed independently. If		Each element in a COSE Key Set MUST be processed independently. If
	one element in a COSE Key Set is either malformed or uses a key that		one element in a COSE Key Set is either malformed or uses a key that
	skipping to change at page 34, line 33 ¶		skipping to change at page 36, line 16 ¶
	1 => tstr / int, ; kty		1 => tstr / int, ; kty
	? 2 => bstr, ; kid		? 2 => bstr, ; kid
	? 3 => tstr / int, ; alg		? 3 => tstr / int, ; alg
	? 4 => [+ (tstr / int) ], ; key_ops		? 4 => [+ (tstr / int) ], ; key_ops
	? 5 => bstr, ; Base IV		? 5 => bstr, ; Base IV
	* label => values		* label => values
	}		}
	COSE_KeySet = [+COSE_Key]		COSE_KeySet = [+COSE_Key]
	7.1. COSE Key Common Parameters		8.1. COSE Key Common Parameters
	This document defines a set of common parameters for a COSE Key		This document defines a set of common parameters for a COSE Key
	object. Table 4 provides a summary of the parameters defined in this		object. Table 5 provides a summary of the parameters defined in this
	section. There are also parameters that are defined for specific key		section. There are also parameters that are defined for specific key
	types. Key-type-specific parameters can be found in		types. Key-type-specific parameters can be found in
	[I-D.ietf-cose-rfc8152bis-algs].		[I-D.ietf-cose-rfc8152bis-algs].
	+---------+-------+----------------+------------+-------------------+		+---------+-------+----------------+------------+-------------------+
	| Name | Label | CBOR Type | Value | Description |		| Name | Label | CBOR Type | Value | Description |
	| | | | Registry | |		| | | | Registry | |
	+---------+-------+----------------+------------+-------------------+		+---------+-------+----------------+------------+-------------------+
	| kty | 1 | tstr / int | COSE Key | Identification of |		| kty | 1 | tstr / int | COSE Key | Identification of |
	| | | | Types | the key type |		| | | | Types | the key type |
	skipping to change at page 35, line 30 ¶		skipping to change at page 36, line 49 ¶
	| | | | | |		| | | | | |
	| key_ops | 4 | [+ (tstr/int)] | | Restrict set of |		| key_ops | 4 | [+ (tstr/int)] | | Restrict set of |
	| | | | | permissible |		| | | | | permissible |
	| | | | | operations |		| | | | | operations |
	| | | | | |		| | | | | |
	| Base IV | 5 | bstr | | Base IV to be |		| Base IV | 5 | bstr | | Base IV to be |
	| | | | | xor-ed with |		| | | | | xor-ed with |
	| | | | | Partial IVs |		| | | | | Partial IVs |
	+---------+-------+----------------+------------+-------------------+		+---------+-------+----------------+------------+-------------------+
	Table 4: Key Map Labels		Table 5: Key Map Labels
	kty: This parameter is used to identify the family of keys for this		kty: This parameter is used to identify the family of keys for this
	structure and, thus, the set of key-type-specific parameters to be		structure and, thus, the set of key-type-specific parameters to be
	found. The set of values defined in this document can be found in		found. The set of values defined in this document can be found in
	[COSE.KeyTypes]. This parameter MUST be present in a key object.		[COSE.KeyTypes]. This parameter MUST be present in a key object.
	Implementations MUST verify that the key type is appropriate for		Implementations MUST verify that the key type is appropriate for
	the algorithm being processed. The key type MUST be included as		the algorithm being processed. The key type MUST be included as
	part of the trust decision process.		part of the trust decision process.
	alg: This parameter is used to restrict the algorithm that is used		alg: This parameter is used to restrict the algorithm that is used
	skipping to change at page 36, line 10 ¶		skipping to change at page 37, line 29 ¶
	kid: This parameter is used to give an identifier for a key. The		kid: This parameter is used to give an identifier for a key. The
	identifier is not structured and can be anything from a user-		identifier is not structured and can be anything from a user-
	provided string to a value computed on the public portion of the		provided string to a value computed on the public portion of the
	key. This field is intended for matching against a 'kid'		key. This field is intended for matching against a 'kid'
	parameter in a message in order to filter down the set of keys		parameter in a message in order to filter down the set of keys
	that need to be checked.		that need to be checked.
	key_ops: This parameter is defined to restrict the set of operations		key_ops: This parameter is defined to restrict the set of operations
	that a key is to be used for. The value of the field is an array		that a key is to be used for. The value of the field is an array
	of values from Table 5. Algorithms define the values of key ops		of values from Table 6. Algorithms define the values of key ops
	that are permitted to appear and are required for specific		that are permitted to appear and are required for specific
	operations. The set of values matches that in [RFC7517] and		operations. The set of values matches that in [RFC7517] and
	[W3C.WebCrypto].		[W3C.WebCrypto].
	Base IV: This parameter is defined to carry the base portion of an		Base IV: This parameter is defined to carry the base portion of an
	IV. It is designed to be used with the Partial IV header		IV. It is designed to be used with the Partial IV header
	parameter defined in Section 3.1. This field provides the ability		parameter defined in Section 3.1. This field provides the ability
	to associate a Partial IV with a key that is then modified on a		to associate a Partial IV with a key that is then modified on a
	per message basis with the Partial IV.		per message basis with the Partial IV.
	skipping to change at page 37, line 28 ¶		skipping to change at page 38, line 30 ¶
	| derive | 7 | The key is used for deriving keys. Requires |		| derive | 7 | The key is used for deriving keys. Requires |
	| key | | private key fields. |		| key | | private key fields. |
	| derive | 8 | The key is used for deriving bits not to be |		| derive | 8 | The key is used for deriving bits not to be |
	| bits | | used as a key. Requires private key fields. |		| bits | | used as a key. Requires private key fields. |
	| MAC | 9 | The key is used for creating MACs. |		| MAC | 9 | The key is used for creating MACs. |
	| create | | |		| create | | |
	| MAC | 10 | The key is used for validating MACs. |		| MAC | 10 | The key is used for validating MACs. |
	| verify | | |		| verify | | |
	+---------+-------+-------------------------------------------------+		+---------+-------+-------------------------------------------------+
	Table 5: Key Operation Values		Table 6: Key Operation Values
	8. Signature Algorithms		9. Signature Algorithms
	There are two signature algorithm schemes. The first is signature		There are two signature algorithm schemes. The first is signature
	with appendix. In this scheme, the message content is processed and		with appendix. In this scheme, the message content is processed and
	a signature is produced; the signature is called the appendix. This		a signature is produced; the signature is called the appendix. This
	is the scheme used by algorithms such as ECDSA and the RSA		is the scheme used by algorithms such as ECDSA and the RSA
	Probabilistic Signature Scheme (RSASSA-PSS). (In fact, the SSA in		Probabilistic Signature Scheme (RSASSA-PSS). (In fact, the SSA in
	RSASSA-PSS stands for Signature Scheme with Appendix.)		RSASSA-PSS stands for Signature Scheme with Appendix.)
	The signature functions for this scheme are:		The signature functions for this scheme are:
	skipping to change at page 38, line 31 ¶		skipping to change at page 39, line 34 ¶
	valid, message content = Verification(message sent, key, signature)		valid, message content = Verification(message sent, key, signature)
	Signature algorithms are used with the COSE_Signature and COSE_Sign1		Signature algorithms are used with the COSE_Signature and COSE_Sign1
	structures. At this time, only signatures with appendixes are		structures. At this time, only signatures with appendixes are
	defined for use with COSE; however, considerable interest has been		defined for use with COSE; however, considerable interest has been
	expressed in using a signature with message recovery algorithm due to		expressed in using a signature with message recovery algorithm due to
	the effective size reduction that is possible. Implementations will		the effective size reduction that is possible. Implementations will
	need to keep this in mind for later possible integration.		need to keep this in mind for later possible integration.
	9. Message Authentication Code (MAC) Algorithms		10. Message Authentication Code (MAC) Algorithms
	Message Authentication Codes (MACs) provide data authentication and		Message Authentication Codes (MACs) provide data authentication and
	integrity protection. They provide either no or very limited data		integrity protection. They provide either no or very limited data
	origination. A MAC, for example, cannot be used to prove the		origination. A MAC, for example, cannot be used to prove the
	identity of the sender to a third party.		identity of the sender to a third party.
	MACs use the same scheme as signature with appendix algorithms. The		MACs use the same scheme as signature with appendix algorithms. The
	message content is processed and an authentication code is produced.		message content is processed and an authentication code is produced.
	The authentication code is frequently called a tag.		The authentication code is frequently called a tag.
	skipping to change at page 38, line 47 ¶		skipping to change at page 40, line 4 ¶
	MACs use the same scheme as signature with appendix algorithms. The		MACs use the same scheme as signature with appendix algorithms. The
	message content is processed and an authentication code is produced.		message content is processed and an authentication code is produced.
	The authentication code is frequently called a tag.		The authentication code is frequently called a tag.
	The MAC functions are:		The MAC functions are:
	tag = MAC_Create(message content, key)		tag = MAC_Create(message content, key)
	valid = MAC_Verify(message content, key, tag)		valid = MAC_Verify(message content, key, tag)
	MAC algorithms can be based on either a block cipher algorithm (i.e.,		MAC algorithms can be based on either a block cipher algorithm (i.e.,
	AES-MAC) or a hash algorithm (i.e., a Hash-based Message		AES-MAC) or a hash algorithm (i.e., a Hash-based Message
	Authentication Code (HMAC)). This document defines a MAC algorithm		Authentication Code (HMAC)). This document defines a MAC algorithm
	using each of these constructions.		using each of these constructions.
	MAC algorithms are used in the COSE_Mac and COSE_Mac0 structures.		MAC algorithms are used in the COSE_Mac and COSE_Mac0 structures.
	10. Content Encryption Algorithms		11. Content Encryption Algorithms
	Content encryption algorithms provide data confidentiality for		Content encryption algorithms provide data confidentiality for
	potentially large blocks of data using a symmetric key. They provide		potentially large blocks of data using a symmetric key. They provide
	integrity on the data that was encrypted; however, they provide		integrity on the data that was encrypted; however, they provide
	either no or very limited data origination. (One cannot, for		either no or very limited data origination. (One cannot, for
	example, be used to prove the identity of the sender to a third		example, be used to prove the identity of the sender to a third
	party.) The ability to provide data origination is linked to how the		party.) The ability to provide data origination is linked to how the
	CEK is obtained.		CEK is obtained.
	COSE restricts the set of legal content encryption algorithms to		COSE restricts the set of legal content encryption algorithms to
	skipping to change at page 39, line 36 ¶		skipping to change at page 40, line 40 ¶
	valid, message content = Decrypt(ciphertext, key, additional data)		valid, message content = Decrypt(ciphertext, key, additional data)
	Most AEAD algorithms are logically defined as returning the message		Most AEAD algorithms are logically defined as returning the message
	content only if the decryption is valid. Many but not all		content only if the decryption is valid. Many but not all
	implementations will follow this convention. The message content		implementations will follow this convention. The message content
	MUST NOT be used if the decryption does not validate.		MUST NOT be used if the decryption does not validate.
	These algorithms are used in COSE_Encrypt and COSE_Encrypt0.		These algorithms are used in COSE_Encrypt and COSE_Encrypt0.
	11. Key Derivation Functions (KDFs)		12. Key Derivation Functions (KDFs)
	KDFs are used to take some secret value and generate a different one.		KDFs are used to take some secret value and generate a different one.
	The secret value comes in three flavors:		The secret value comes in three flavors:
	o Secrets that are uniformly random: This is the type of secret that		o Secrets that are uniformly random: This is the type of secret that
	is created by a good random number generator.		is created by a good random number generator.
	o Secrets that are not uniformly random: This is type of secret that		o Secrets that are not uniformly random: This is type of secret that
	is created by operations like key agreement.		is created by operations like key agreement.
	o Secrets that are not random: This is the type of secret that		o Secrets that are not random: This is the type of secret that
	people generate for things like passwords.		people generate for things like passwords.
	General KDFs work well with the first type of secret, can do		General KDFs work well with the first type of secret, can do
	reasonably well with the second type of secret, and generally do		reasonably well with the second type of secret, and generally do
	poorly with the last type of secret. Functions like PBES2 [RFC8018]		poorly with the last type of secret. Functions like PBES2 [RFC8018]
	need to be used for non-random secrets.		need to be used for non-random secrets.
	The same KDF can be set up to deal with the first two types of		The same KDF can be set up to deal with the first two types of
	secrets in a different way. The KDF defined in !!! HDKF !!! (section		secrets in a different way. The KDF defined in section 5.1 of
	XXXX of [I-D.ietf-cose-rfc8152bis-algs]) is such a function. This is		[I-D.ietf-cose-rfc8152bis-algs] is such a function. This is
	reflected in the set of algorithms defined around the HMAC-based		reflected in the set of algorithms defined around the HMAC-based
	Extract-and-Expand Key Derivation Function (HKDF).		Extract-and-Expand Key Derivation Function (HKDF).
	When using KDFs, one component that is included is context		When using KDFs, one component that is included is context
	information. Context information is used to allow for different		information. Context information is used to allow for different
	keying information to be derived from the same secret. The use of		keying information to be derived from the same secret. The use of
	context-based keying material is considered to be a good security		context-based keying material is considered to be a good security
	practice.		practice.
	12. Content Key Distribution Methods		13. Content Key Distribution Methods
	Content key distribution methods (recipient algorithms) can be		Content key distribution methods (recipient algorithms) can be
	defined into a number of different classes. COSE has the ability to		defined into a number of different classes. COSE has the ability to
	support many classes of recipient algorithms. In this section, a		support many classes of recipient algorithms. In this section, a
	number of classes are listed. The names of the recipient algorithm		number of classes are listed. The names of the recipient algorithm
	classes used here are the same as those defined in [RFC7516]. Other		classes used here are the same as those defined in [RFC7516]. Other
	specifications use different terms for the recipient algorithm		specifications use different terms for the recipient algorithm
	classes or do not support some of the recipient algorithm classes.		classes or do not support some of the recipient algorithm classes.
	12.1. Direct Encryption		13.1. Direct Encryption
	The direct encryption class algorithms share a secret between the		The direct encryption class algorithms share a secret between the
	sender and the recipient that is used either directly or after		sender and the recipient that is used either directly or after
	manipulation as the CEK. When direct encryption mode is used, it		manipulation as the CEK. When direct encryption mode is used, it
	MUST be the only mode used on the message.		MUST be the only mode used on the message.
	The COSE_Recipient structure for the recipient is organized as		The COSE_Recipient structure for the recipient is organized as
	follows:		follows:
	o The 'protected' field MUST be a zero-length item unless it is used		o The 'protected' field MUST be a zero-length item unless it is used
	in the computation of the content key.		in the computation of the content key.
	o The 'alg' parameter MUST be present.		o The 'alg' parameter MUST be present.
	o A parameter identifying the shared secret SHOULD be present.		o A parameter identifying the shared secret SHOULD be present.
	o The 'ciphertext' field MUST be a zero-length item.		o The 'ciphertext' field MUST be a zero-length item.
	o The 'recipients' field MUST be absent.		o The 'recipients' field MUST be absent.
	12.2. Key Wrap		13.2. Key Wrap
	In key wrap mode, the CEK is randomly generated and that key is then		In key wrap mode, the CEK is randomly generated and that key is then
	encrypted by a shared secret between the sender and the recipient.		encrypted by a shared secret between the sender and the recipient.
	All of the currently defined key wrap algorithms for COSE are AE		All of the currently defined key wrap algorithms for COSE are AE
	algorithms. Key wrap mode is considered to be superior to direct		algorithms. Key wrap mode is considered to be superior to direct
	encryption if the system has any capability for doing random key		encryption if the system has any capability for doing random key
	generation. This is because the shared key is used to wrap random		generation. This is because the shared key is used to wrap random
	data rather than data that has some degree of organization and may in		data rather than data that has some degree of organization and may in
	fact be repeating the same content. The use of key wrap loses the		fact be repeating the same content. The use of key wrap loses the
	weak data origination that is provided by the direct encryption		weak data origination that is provided by the direct encryption
	skipping to change at page 41, line 36 ¶		skipping to change at page 42, line 38 ¶
	recipient is an acceptable way of dealing with it. Failing to		recipient is an acceptable way of dealing with it. Failing to
	process the message is not an acceptable way of dealing with it.		process the message is not an acceptable way of dealing with it.
	o The plaintext to be encrypted is the key from next layer down		o The plaintext to be encrypted is the key from next layer down
	(usually the content layer).		(usually the content layer).
	o At a minimum, the 'unprotected' field MUST contain the 'alg'		o At a minimum, the 'unprotected' field MUST contain the 'alg'
	parameter and SHOULD contain a parameter identifying the shared		parameter and SHOULD contain a parameter identifying the shared
	secret.		secret.
	12.3. Key Transport		13.3. Key Transport
	Key transport mode is also called key encryption mode in some		Key transport mode is also called key encryption mode in some
	standards. Key transport mode differs from key wrap mode in that it		standards. Key transport mode differs from key wrap mode in that it
	uses an asymmetric encryption algorithm rather than a symmetric		uses an asymmetric encryption algorithm rather than a symmetric
	encryption algorithm to protect the key. A set of key transport		encryption algorithm to protect the key. A set of key transport
	algorithms are defined in [RFC8230].		algorithms are defined in [RFC8230].
	When using a key transport algorithm, the COSE_Encrypt structure for		When using a key transport algorithm, the COSE_Encrypt structure for
	the recipient is organized as follows:		the recipient is organized as follows:
	o The 'protected' field MUST be absent.		o The 'protected' field MUST be absent.
	o The plaintext to be encrypted is the key from the next layer down		o The plaintext to be encrypted is the key from the next layer down
	(usually the content layer).		(usually the content layer).
	o At a minimum, the 'unprotected' field MUST contain the 'alg'		o At a minimum, the 'unprotected' field MUST contain the 'alg'
	parameter and SHOULD contain a parameter identifying the		parameter and SHOULD contain a parameter identifying the
	asymmetric key.		asymmetric key.
	12.4. Direct Key Agreement		13.4. Direct Key Agreement
	The 'direct key agreement' class of recipient algorithms uses a key		The 'direct key agreement' class of recipient algorithms uses a key
	agreement method to create a shared secret. A KDF is then applied to		agreement method to create a shared secret. A KDF is then applied to
	the shared secret to derive a key to be used in protecting the data.		the shared secret to derive a key to be used in protecting the data.
	This key is normally used as a CEK or MAC key, but could be used for		This key is normally used as a CEK or MAC key, but could be used for
	other purposes if more than two layers are in use (see Appendix B).		other purposes if more than two layers are in use (see Appendix B).
	The most commonly used key agreement algorithm is Diffie-Hellman, but		The most commonly used key agreement algorithm is Diffie-Hellman, but
	other variants exist. Since COSE is designed for a store and forward		other variants exist. Since COSE is designed for a store and forward
	environment rather than an online environment, many of the DH		environment rather than an online environment, many of the DH
	skipping to change at page 43, line 5 ¶		skipping to change at page 44, line 5 ¶
	The COSE_Encrypt structure for the recipient is organized as follows:		The COSE_Encrypt structure for the recipient is organized as follows:
	o At a minimum, headers MUST contain the 'alg' parameter and SHOULD		o At a minimum, headers MUST contain the 'alg' parameter and SHOULD
	contain a parameter identifying the recipient's asymmetric key.		contain a parameter identifying the recipient's asymmetric key.
	o The headers SHOULD identify the sender's key for the static-static		o The headers SHOULD identify the sender's key for the static-static
	versions and MUST contain the sender's ephemeral key for the		versions and MUST contain the sender's ephemeral key for the
	ephemeral-static versions.		ephemeral-static versions.
	12.5. Key Agreement with Key Wrap		13.5. Key Agreement with Key Wrap
	Key Agreement with Key Wrap uses a randomly generated CEK. The CEK		Key Agreement with Key Wrap uses a randomly generated CEK. The CEK
	is then encrypted using a key wrap algorithm and a key derived from		is then encrypted using a key wrap algorithm and a key derived from
	the shared secret computed by the key agreement algorithm. The		the shared secret computed by the key agreement algorithm. The
	function for this would be:		function for this would be:
	encryptedKey = KeyWrap(KDF(DH-Shared, context), CEK)		encryptedKey = KeyWrap(KDF(DH-Shared, context), CEK)
	The COSE_Encrypt structure for the recipient is organized as follows:		The COSE_Encrypt structure for the recipient is organized as follows:
	o The 'protected' field is fed into the KDF context structure.		o The 'protected' field is fed into the KDF context structure.
	o The plaintext to be encrypted is the key from the next layer down		o The plaintext to be encrypted is the key from the next layer down
	(usually the content layer).		(usually the content layer).
	o The 'alg' parameter MUST be present in the layer.		o The 'alg' parameter MUST be present in the layer.
	o A parameter identifying the recipient's key SHOULD be present. A		o A parameter identifying the recipient's key SHOULD be present. A
	parameter identifying the sender's key SHOULD be present.		parameter identifying the sender's key SHOULD be present.
	13. CBOR Encoder Restrictions		14. CBOR Encoding Restrictions
	There has been an attempt to limit the number of places where the		There has been an attempt to limit the number of places where the
	document needs to impose restrictions on how the CBOR Encoder needs		document needs to impose restrictions on how the CBOR Encoder needs
	to work. We have managed to narrow it down to the following		to work. We have managed to narrow it down to the following
	restrictions:		restrictions:
	o The restriction applies to the encoding of the COSE_KDF_Context,		o The restriction applies to the encoding of the Sig_structure, the
	the Sig_structure, the Enc_structure, and the MAC_structure.		Enc_structure, and the MAC_structure.
	o The rules for "Canonical CBOR" (Section 3.9 of RFC 7049) MUST be		o Encoding MUST be done using definite lengths and the length of the
	used in these locations. The main rule that needs to be enforced		MUST be the minimum possible length. This means that the integer
	is that all lengths in these structures MUST be encoded such that		1 is encoded as "0x01" and not "0x1801".
	they are using definite lengths, and the minimum length encoding
	is used.
	o Applications MUST NOT generate messages with the same label used		o Applications MUST NOT generate messages with the same label used
	twice as a key in a single map. Applications MUST NOT parse and		twice as a key in a single map. Applications MUST NOT parse and
	process messages with the same label used twice as a key in a		process messages with the same label used twice as a key in a
	single map. Applications can enforce the parse and process		single map. Applications can enforce the parse and process
	requirement by using parsers that will fail the parse step or by		requirement by using parsers that will fail the parse step or by
	using parsers that will pass all keys to the application, and the		using parsers that will pass all keys to the application, and the
	application can perform the check for duplicate keys.		application can perform the check for duplicate keys.
	14. Application Profiling Considerations		15. Application Profiling Considerations
	This document is designed to provide a set of security services, but		This document is designed to provide a set of security services, but
	not impose algorithm implementation requirements for specific usage.		not impose algorithm implementation requirements for specific usage.
	The interoperability requirements are provided for how each of the		The interoperability requirements are provided for how each of the
	individual services are used and how the algorithms are to be used		individual services are used and how the algorithms are to be used
	for interoperability. The requirements about which algorithms and		for interoperability. The requirements about which algorithms and
	which services are needed are deferred to each application.		which services are needed are deferred to each application.
	An example of a profile can be found in		An example of a profile can be found in
	[I-D.ietf-core-object-security] where a profiles was developed for		[I-D.ietf-core-object-security] where a profiles was developed for
	skipping to change at page 45, line 22 ¶		skipping to change at page 46, line 16 ¶
	* Advertising in the message (S/MIME capabilities) [RFC5751].		* Advertising in the message (S/MIME capabilities) [RFC5751].
	* Advertising in the certificate (capabilities extension)		* Advertising in the certificate (capabilities extension)
	[RFC4262].		[RFC4262].
	* Minimum requirements for the S/MIME, which have been updated		* Minimum requirements for the S/MIME, which have been updated
	over time [RFC2633] [RFC5751] (note that [RFC2633] has been		over time [RFC2633] [RFC5751] (note that [RFC2633] has been
	obsoleted by [RFC5751]).		obsoleted by [RFC5751]).
	15. IANA Considerations		16. IANA Considerations
	The registeries and registrations listed below were created during		The registeries and registrations listed below were created during
	processing of RFC 8152 [RFC8152]. The only known action at this time		processing of RFC 8152 [RFC8152]. The only known action at this time
	is to update the references.		is to update the references.
	15.1. CBOR Tag Assignment		16.1. CBOR Tag Assignment
	IANA assigned tags in the "CBOR Tags" registry as part of processing		IANA assigned tags in the "CBOR Tags" registry as part of processing
	[RFC8152]. IANA is requested to update the references from [RFC8152]		[RFC8152]. IANA is requested to update the references from [RFC8152]
	to this document.		to this document.
	15.2. COSE Header Parameters Registry		IANA is requested to register a new tag for the CounterSignature
			type.
			Tag: TBD0
			Data Item: COSE_Signature
			Semantics: COSE standalone counter signature
			Reference: [[this document]]
			16.2. COSE Header Parameters Registry
	IANA created a registry titled "COSE Header Parameters" as part of		IANA created a registry titled "COSE Header Parameters" as part of
	processing [RFC8152]. The registry has been created to use the		processing [RFC8152]. The registry has been created to use the
	"Expert Review Required" registration procedure [RFC8126].		"Expert Review Required" registration procedure [RFC8126].
	IANA is requested to update the reference for entries in the table		IANA is requested to update the reference for entries in the table
	from [RFC8152] to this document. This document does not update the		from [RFC8152] to this document. This document does not update the
	expert review guidelines provided in [RFC8152].		expert review guidelines provided in [RFC8152].
	15.3. COSE Header Algorithm Parameters Registry		16.3. COSE Header Algorithm Parameters Registry
	IANA created a registry titled "COSE Header Algorithm Parameters" as		IANA created a registry titled "COSE Header Algorithm Parameters" as
	part of processing [RFC8152]. The registry has been created to use		part of processing [RFC8152]. The registry has been created to use
	the "Expert Review Required" registration procedure [RFC8126].		the "Expert Review Required" registration procedure [RFC8126].
	IANA is requested to update the references from [RFC8152] to this		IANA is requested to update the references from [RFC8152] to this
	document. This document does not update the expert review guidelines		document. This document does not update the expert review guidelines
	provided in [RFC8152].		provided in [RFC8152].
	15.4. COSE Key Common Parameters Registry		16.4. COSE Key Common Parameters Registry
	IANA created a registry titled "COSE Key Common Parameters" as part		IANA created a registry titled "COSE Key Common Parameters" as part
	of the processing of [RFC8152]. The registry has been created to use		of the processing of [RFC8152]. The registry has been created to use
	the "Expert Review Required" registration procedure [RFC8126].		the "Expert Review Required" registration procedure [RFC8126].
	IANA is requested to update the reference for entries in the table		IANA is requested to update the reference for entries in the table
	from [RFC8152] to this document. This document does not update the		from [RFC8152] to this document. This document does not update the
	expert review guidelines provided in [RFC8152].		expert review guidelines provided in [RFC8152].
	15.5. Media Type Registrations		16.5. Media Type Registrations
	15.5.1. COSE Security Message		16.5.1. COSE Security Message
	This section registers the 'application/cose' media type in the		This section registers the 'application/cose' media type in the
	"Media Types" registry. These media types are used to indicate that		"Media Types" registry. These media types are used to indicate that
	the content is a COSE message.		the content is a COSE message.
	Type name: application		Type name: application
	Subtype name: cose		Subtype name: cose
	Required parameters: N/A		Required parameters: N/A
	Optional parameters: cose-type		Optional parameters: cose-type
	Encoding considerations: binary		Encoding considerations: binary
	Security considerations: See the Security Considerations section		Security considerations: See the Security Considerations section
	of [[This Document]].		of [[This Document]].
	Interoperability considerations: N/A		Interoperability considerations: N/A
	Published specification: RFC 8152		Published specification: [[this document]]
	Applications that use this media type: IoT applications sending		Applications that use this media type: IoT applications sending
	security content over HTTP(S) transports.		security content over HTTP(S) transports.
	Fragment identifier considerations: N/A		Fragment identifier considerations: N/A
	Additional information:		Additional information:
	* Deprecated alias names for this type: N/A		* Deprecated alias names for this type: N/A
	skipping to change at page 47, line 19 ¶		skipping to change at page 48, line 30 ¶
	Intended usage: COMMON		Intended usage: COMMON
	Restrictions on usage: N/A		Restrictions on usage: N/A
	Author: Jim Schaad, ietf@augustcellars.com		Author: Jim Schaad, ietf@augustcellars.com
	Change Controller: IESG		Change Controller: IESG
	Provisional registration? No		Provisional registration? No
	15.5.2. COSE Key Media Type		16.5.2. COSE Key Media Type
	This section registers the 'application/cose-key' and 'application/		This section registers the 'application/cose-key' and 'application/
	cose-key-set' media types in the "Media Types" registry. These media		cose-key-set' media types in the "Media Types" registry. These media
	types are used to indicate, respectively, that content is a COSE_Key		types are used to indicate, respectively, that content is a COSE_Key
	or COSE_KeySet object.		or COSE_KeySet object.
	The template for registering 'application/cose-key' is:		The template for registering 'application/cose-key' is:
	Type name: application		Type name: application
	skipping to change at page 47, line 42 ¶		skipping to change at page 49, line 4 ¶
	Required parameters: N/A		Required parameters: N/A
	Optional parameters: N/A		Optional parameters: N/A
	Encoding considerations: binary		Encoding considerations: binary
	Security considerations: See the Security Considerations section		Security considerations: See the Security Considerations section
	of [[This Document]].		of [[This Document]].
	Interoperability considerations: N/A		Interoperability considerations: N/A
			Published specification: [[this document]]
	Published specification: RFC 8152
	Applications that use this media type: Distribution of COSE based		Applications that use this media type: Distribution of COSE based
	keys for IoT applications.		keys for IoT applications.
	Fragment identifier considerations: N/A		Fragment identifier considerations: N/A
	Additional information:		Additional information:
	* Deprecated alias names for this type: N/A		* Deprecated alias names for this type: N/A
	skipping to change at page 48, line 43 ¶		skipping to change at page 49, line 51 ¶
	Optional parameters: N/A		Optional parameters: N/A
	Encoding considerations: binary		Encoding considerations: binary
	Security considerations: See the Security Considerations section		Security considerations: See the Security Considerations section
	of [[This Document]].		of [[This Document]].
	Interoperability considerations: N/A		Interoperability considerations: N/A
	Published specification: RFC 8152		Published specification: [[this document]]
	Applications that use this media type: Distribution of COSE based		Applications that use this media type: Distribution of COSE based
	keys for IoT applications.		keys for IoT applications.
	Fragment identifier considerations: N/A		Fragment identifier considerations: N/A
	Additional information:		Additional information:
	* Deprecated alias names for this type: N/A		* Deprecated alias names for this type: N/A
	* Magic number(s): N/A		* Magic number(s): N/A
	* File extension(s): cbor		* File extension(s): cbor
	* Macintosh file type code(s): N/A		* Macintosh file type code(s): N/A
	Person & email address to contact for further information:		Person & email address to contact for further information:
	iesg@ietf.org		iesg@ietf.org
	Intended usage: COMMON		Intended usage: COMMON
	skipping to change at page 49, line 23 ¶		skipping to change at page 50, line 32 ¶
	Intended usage: COMMON		Intended usage: COMMON
	Restrictions on usage: N/A		Restrictions on usage: N/A
	Author: Jim Schaad, ietf@augustcellars.com		Author: Jim Schaad, ietf@augustcellars.com
	Change Controller: IESG		Change Controller: IESG
	Provisional registration? No		Provisional registration? No
	15.6. CoAP Content-Formats Registry		16.6. CoAP Content-Formats Registry
	IANA added the following entries to the "CoAP Content-Formats"		IANA added the following entries to the "CoAP Content-Formats"
	registry while processing [RFC8152]. IANA is requested to update the		registry while processing [RFC8152]. IANA is requested to update the
	reference value from [RFC8152] to [[This Document]].		reference value from [RFC8152] to [[This Document]].
	15.7. Expert Review Instructions		17. Security Considerations
	All of the IANA registries established in this document are defined
	as expert review. This section gives some general guidelines for
	what the experts should be looking for, but they are being designated
	as experts for a reason, so they should be given substantial
	latitude.
	Expert reviewers should take into consideration the following points:
	o Point squatting should be discouraged. Reviewers are encouraged
	to get sufficient information for registration requests to ensure
	that the usage is not going to duplicate one that is already
	registered, and that the point is likely to be used in
	deployments. The zones tagged as private use are intended for
	testing purposes and closed environments; code points in other
	ranges should not be assigned for testing.
	o Specifications are required for the standards track range of point
	assignment. Specifications should exist for specification
	required ranges, but early assignment before a specification is
	available is considered to be permissible. Specifications are
	needed for the first-come, first-serve range if they are expected
	to be used outside of closed environments in an interoperable way.
	When specifications are not provided, the description provided
	needs to have sufficient information to identify what the point is
	being used for.
	o Experts should take into account the expected usage of fields when
	approving point assignment. The fact that there is a range for
	standards track documents does not mean that a standards track
	document cannot have points assigned outside of that range. The
	length of the encoded value should be weighed against how many
	code points of that length are left, the size of device it will be
	used on, and the number of code points left that encode to that
	size.
	o When algorithms are registered, vanity registrations should be
	discouraged. One way to do this is to require registrations to
	provide additional documentation on security analysis of the
	algorithm. Another thing that should be considered is requesting
	an opinion on the algorithm from the Crypto Forum Research Group
	(CFRG). Algorithms that do not meet the security requirements of
	the community and the messages structures should not be
	registered.
	16. Security Considerations
	There are a number of security considerations that need to be taken		There are a number of security considerations that need to be taken
	into account by implementers of this specification. The security		into account by implementers of this specification. The security
	considerations that are specific to an individual algorithm are		considerations that are specific to an individual algorithm are
	placed next to the description of the algorithm. While some		placed next to the description of the algorithm. While some
	considerations have been highlighted here, additional considerations		considerations have been highlighted here, additional considerations
	may be found in the documents listed in the references.		may be found in the documents listed in the references.
	Implementations need to protect the private key material for any		Implementations need to protect the private key material for any
	individuals. There are some cases in this document that need to be		individuals. There are some cases in this document that need to be
	skipping to change at page 52, line 24 ¶		skipping to change at page 52, line 35 ¶
	analysis of encrypted messages based on the length of the message.		analysis of encrypted messages based on the length of the message.
	This specification does not provide for a uniform method of providing		This specification does not provide for a uniform method of providing
	padding as part of the message structure. An observer can		padding as part of the message structure. An observer can
	distinguish between two different strings (for example, 'YES' and		distinguish between two different strings (for example, 'YES' and
	'NO') based on the length for all of the content encryption		'NO') based on the length for all of the content encryption
	algorithms that are defined in this document. This means that it is		algorithms that are defined in this document. This means that it is
	up to the applications to document how content padding is to be done		up to the applications to document how content padding is to be done
	in order to prevent or discourage such analysis. (For example, the		in order to prevent or discourage such analysis. (For example, the
	strings could be defined as 'YES' and 'NO '.)		strings could be defined as 'YES' and 'NO '.)
	17. Implementation Status		18. Implementation Status
	This section records the status of known implementations of the		This section records the status of known implementations of the
	protocol defined by this specification at the time of posting of this		protocol defined by this specification at the time of posting of this
	Internet-Draft, and is based on a proposal described in [RFC7942].		Internet-Draft, and is based on a proposal described in [RFC7942].
	The description of implementations in this section is intended to		The description of implementations in this section is intended to
	assist the IETF in its decision processes in progressing drafts to		assist the IETF in its decision processes in progressing drafts to
	RFCs. Please note that the listing of any individual implementation		RFCs. Please note that the listing of any individual implementation
	here does not imply endorsement by the IETF. Furthermore, no effort		here does not imply endorsement by the IETF. Furthermore, no effort
	has been spent to verify the information presented here that was		has been spent to verify the information presented here that was
	supplied by IETF contributors. This is not intended as, and must not		supplied by IETF contributors. This is not intended as, and must not
	skipping to change at page 52, line 46 ¶		skipping to change at page 53, line 9 ¶
	features. Readers are advised to note that other implementations may		features. Readers are advised to note that other implementations may
	exist.		exist.
	According to [RFC7942], "this will allow reviewers and working groups		According to [RFC7942], "this will allow reviewers and working groups
	to assign due consideration to documents that have the benefit of		to assign due consideration to documents that have the benefit of
	running code, which may serve as evidence of valuable experimentation		running code, which may serve as evidence of valuable experimentation
	and feedback that have made the implemented protocols more mature.		and feedback that have made the implemented protocols more mature.
	It is up to the individual working groups to use this information as		It is up to the individual working groups to use this information as
	they see fit".		they see fit".
	17.1. Author's Versions		18.1. Author's Versions
	There are three different implementations that have been created by		There are three different implementations that have been created by
	the author of the document both to create the examples that are		the author of the document both to create the examples that are
	included in the document and to validate the structures and		included in the document and to validate the structures and
	methodology used in the design of COSE.		methodology used in the design of COSE.
	Implementation Location: https://github.com/cose-wg		Implementation Location: https://github.com/cose-wg
	Primary Maintainer: Jim Schaad		Primary Maintainer: Jim Schaad
	skipping to change at page 53, line 34 ¶		skipping to change at page 53, line 45 ¶
	libraries. All three libraries have tests to allow for the		libraries. All three libraries have tests to allow for the
	creating of the same messages that are in the example library		creating of the same messages that are in the example library
	followed by validating them. These are not compared against the		followed by validating them. These are not compared against the
	example library. The Java and C# libraries have unit testing		example library. The Java and C# libraries have unit testing
	included. Not all of the MUST statements in the document have		included. Not all of the MUST statements in the document have
	been implemented as part of the libraries. One such statement is		been implemented as part of the libraries. One such statement is
	the requirement that unique labels be present.		the requirement that unique labels be present.
	Licensing: Revised BSD License		Licensing: Revised BSD License
	17.2. Java Script Version		18.2. Java Script Version
	Implementation Location: https://github.com/erdtman/cose-js		Implementation Location: https://github.com/erdtman/cose-js
	Primary Maintainer: Samuel Erdtman		Primary Maintainer: Samuel Erdtman
	Languages: JavaScript		Languages: JavaScript
	Cryptography: TBD		Cryptography: TBD
	Coverage: Full Encrypt, Signature and MAC objects are supported.		Coverage: Full Encrypt, Signature and MAC objects are supported.
	Testing: Basic testing against the common example library.		Testing: Basic testing against the common example library.
	Licensing: Apache License 2.0		Licensing: Apache License 2.0
	17.3. Python Version		18.3. Python Version
	Implementation Location: https://github.com/TimothyClaeys/COSE-		Implementation Location: https://github.com/TimothyClaeys/COSE-
	PYTHON		PYTHON
	Primary Maintainer: Timothy Claeys		Primary Maintainer: Timothy Claeys
	Languages: Python		Languages: Python
	Cryptography: pyecdsak, crypto python libraries		Cryptography: pyecdsak, crypto python libraries
	Coverage: TBD		Coverage: TBD
	Testing: Basic testing plus running against the common example		Testing: Basic testing plus running against the common example
	library.		library.
	Licensing: BSD 3-Clause License		Licensing: BSD 3-Clause License
	17.4. COSE Testing Library		18.4. COSE Testing Library
	Implementation Location: https://github.com/cose-wg/Examples		Implementation Location: https://github.com/cose-wg/Examples
	Primary Maintainer: Jim Schaad		Primary Maintainer: Jim Schaad
	Description: A set of tests for the COSE library is provided as		Description: A set of tests for the COSE library is provided as
	part of the implementation effort. Both success and fail tests		part of the implementation effort. Both success and fail tests
	have been provided. All of the examples in this document are part		have been provided. All of the examples in this document are part
	of this example set.		of this example set.
	Coverage: An attempt has been made to have test cases for every		Coverage: An attempt has been made to have test cases for every
	message type and algorithm in the document. Currently examples		message type and algorithm in the document. Currently examples
	dealing with counter signatures, and ECDH with Curve24459 and		dealing with counter signatures, and ECDH with Curve24459 and
	Goldilocks are missing.		Goldilocks are missing.
	Licensing: Public Domain		Licensing: Public Domain
	18. References		19. References
	18.1. Normative References		19.1. Normative References
	[COAP.Formats]		[COAP.Formats]
	IANA, "CoAP Content-Formats",		IANA, "CoAP Content-Formats",
	<https://www.iana.org/assignments/core-parameters/		<https://www.iana.org/assignments/core-parameters/
	core-parameters.xhtml#content-formats>.		core-parameters.xhtml#content-formats>.
	[COSE.Algorithms]		[COSE.Algorithms]
	IANA, "COSE Algorithms",		IANA, "COSE Algorithms",
	<https://www.iana.org/assignments/cose/		<https://www.iana.org/assignments/cose/
	cose.xhtml#algorithms>.		cose.xhtml#algorithms>.
	skipping to change at page 55, line 27 ¶		skipping to change at page 55, line 36 ¶
	<https://www.iana.org/assignments/cose/		<https://www.iana.org/assignments/cose/
	cose.xhtml#algorithms>.		cose.xhtml#algorithms>.
	[DSS] National Institute of Standards and Technology, "Digital		[DSS] National Institute of Standards and Technology, "Digital
	Signature Standard (DSS)", FIPS PUB 186-4,		Signature Standard (DSS)", FIPS PUB 186-4,
	DOI 10.6028/NIST.FIPS.186-4, July 2013,		DOI 10.6028/NIST.FIPS.186-4, July 2013,
	<http://nvlpubs.nist.gov/nistpubs/FIPS/		<http://nvlpubs.nist.gov/nistpubs/FIPS/
	NIST.FIPS.186-4.pdf>.		NIST.FIPS.186-4.pdf>.
	[I-D.ietf-cose-rfc8152bis-algs]		[I-D.ietf-cose-rfc8152bis-algs]
	Schaad, J., "CBOR Algorithms for Object Signing and		Schaad, J., "CBOR Object Signing and Encryption (COSE):
	Encryption (COSE)", draft-ietf-cose-rfc8152bis-algs-01		Initial Algorithms", draft-ietf-cose-rfc8152bis-algs-02
	(work in progress), February 2019.		(work in progress), March 2019.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object		[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
	Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,		Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
	October 2013, <https://www.rfc-editor.org/info/rfc7049>.		October 2013, <https://www.rfc-editor.org/info/rfc7049>.
	[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital		[RFC8032] Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
	Signature Algorithm (EdDSA)", RFC 8032,		Signature Algorithm (EdDSA)", RFC 8032,
	DOI 10.17487/RFC8032, January 2017,		DOI 10.17487/RFC8032, January 2017,
	<https://www.rfc-editor.org/info/rfc8032>.		<https://www.rfc-editor.org/info/rfc8032>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	18.2. Informative References		19.2. Informative References
	[I-D.ietf-cbor-cddl]		[I-D.ietf-cbor-cddl]
	Birkholz, H., Vigano, C., and C. Bormann, "Concise data		Birkholz, H., Vigano, C., and C. Bormann, "Concise data
	definition language (CDDL): a notational convention to		definition language (CDDL): a notational convention to
	express CBOR and JSON data structures", draft-ietf-cbor-		express CBOR and JSON data structures", draft-ietf-cbor-
	cddl-07 (work in progress), February 2019.		cddl-08 (work in progress), March 2019.
	[I-D.ietf-core-object-security]		[I-D.ietf-core-object-security]
	Selander, G., Mattsson, J., Palombini, F., and L. Seitz,		Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
	"Object Security for Constrained RESTful Environments		"Object Security for Constrained RESTful Environments
	(OSCORE)", draft-ietf-core-object-security-15 (work in		(OSCORE)", draft-ietf-core-object-security-16 (work in
	progress), August 2018.		progress), March 2019.
	[PVSig] Brown, D. and D. Johnson, "Formal Security Proofs for a		[PVSig] Brown, D. and D. Johnson, "Formal Security Proofs for a
	Signature Scheme with Partial Message Recovery",		Signature Scheme with Partial Message Recovery",
	DOI 10.1007/3-540-45353-9_11, LNCS Volume 2020, June 2000.		DOI 10.1007/3-540-45353-9_11, LNCS Volume 2020, June 2000.
	[RFC2633] Ramsdell, B., Ed., "S/MIME Version 3 Message		[RFC2633] Ramsdell, B., Ed., "S/MIME Version 3 Message
	Specification", RFC 2633, DOI 10.17487/RFC2633, June 1999,		Specification", RFC 2633, DOI 10.17487/RFC2633, June 1999,
	<https://www.rfc-editor.org/info/rfc2633>.		<https://www.rfc-editor.org/info/rfc2633>.
	[RFC4262] Santesson, S., "X.509 Certificate Extension for Secure/		[RFC4262] Santesson, S., "X.509 Certificate Extension for Secure/
	Multipurpose Internet Mail Extensions (S/MIME)		Multipurpose Internet Mail Extensions (S/MIME)
	Capabilities", RFC 4262, DOI 10.17487/RFC4262, December		Capabilities", RFC 4262, DOI 10.17487/RFC4262, December
	2005, <https://www.rfc-editor.org/info/rfc4262>.		2005, <https://www.rfc-editor.org/info/rfc4262>.
	[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",		[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
	FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,		FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
	<https://www.rfc-editor.org/info/rfc4949>.		<https://www.rfc-editor.org/info/rfc4949>.
			[RFC4998] Gondrom, T., Brandner, R., and U. Pordesch, "Evidence
			Record Syntax (ERS)", RFC 4998, DOI 10.17487/RFC4998,
			August 2007, <https://www.rfc-editor.org/info/rfc4998>.
	[RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated		[RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated
	Encryption", RFC 5116, DOI 10.17487/RFC5116, January 2008,		Encryption", RFC 5116, DOI 10.17487/RFC5116, January 2008,
	<https://www.rfc-editor.org/info/rfc5116>.		<https://www.rfc-editor.org/info/rfc5116>.
	[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,		[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
	RFC 5652, DOI 10.17487/RFC5652, September 2009,		RFC 5652, DOI 10.17487/RFC5652, September 2009,
	<https://www.rfc-editor.org/info/rfc5652>.		<https://www.rfc-editor.org/info/rfc5652>.
	[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet		[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
	Mail Extensions (S/MIME) Version 3.2 Message		Mail Extensions (S/MIME) Version 3.2 Message
	skipping to change at page 58, line 25 ¶		skipping to change at page 58, line 35 ¶
	Interchange Format", STD 90, RFC 8259,		Interchange Format", STD 90, RFC 8259,
	DOI 10.17487/RFC8259, December 2017,		DOI 10.17487/RFC8259, December 2017,
	<https://www.rfc-editor.org/info/rfc8259>.		<https://www.rfc-editor.org/info/rfc8259>.
	[W3C.WebCrypto]		[W3C.WebCrypto]
	Watson, M., "Web Cryptography API", W3C Recommendation,		Watson, M., "Web Cryptography API", W3C Recommendation,
	January 2017, <https://www.w3.org/TR/WebCryptoAPI/>.		January 2017, <https://www.w3.org/TR/WebCryptoAPI/>.
	Appendix A. Guidelines for External Data Authentication of Algorithms		Appendix A. Guidelines for External Data Authentication of Algorithms
	A portion of the working group has expressed a strong desire to relax		During development of COSE, the requirement that the algorithm
	the rule that the algorithm identifier be required to appear in each		identifier be located in the protected attributes was relaxed from a
	level of a COSE object. There are two basic reasons that have been		must to a should. There were two basic reasons that have been
	advanced to support this position. First, the resulting message will		advanced to support this position. First, the resulting message will
	be smaller if the algorithm identifier is omitted from the most		be smaller if the algorithm identifier is omitted from the most
	common messages in a CoAP environment. Second, there is a potential		common messages in a CoAP environment. Second, there is a potential
	bug that will arise if full checking is not done correctly between		bug that will arise if full checking is not done correctly between
	the different places that an algorithm identifier could be placed		the different places that an algorithm identifier could be placed
	(the message itself, an application statement, the key structure that		(the message itself, an application statement, the key structure that
	the sender possesses, and the key structure the recipient possesses).		the sender possesses, and the key structure the recipient possesses).
	This appendix lays out how such a change can be made and the details		This appendix lays out how such a change can be made and the details
	that an application needs to specify in order to use this option.		that an application needs to specify in order to use this option.
	Two different sets of details are specified: those needed to omit an		Two different sets of details are specified: those needed to omit an
	algorithm identifier and those needed to use a variant on the counter		algorithm identifier and those needed to use a variant on the counter
	signature attribute that contains no attributes about itself.		signature attribute that contains no attributes about itself.
	A.1. Algorithm Identification		Three sets of recommendations are laid out. The first set of
			recommendations apply to having an implicit algorithm identified for
	In this section, three sets of recommendations are laid out. The		a single layer of a COSE object. The second set of recommendations
	first set of recommendations apply to having an implicit algorithm		apply to having multiple implicit algorithms identified for multiple
	identified for a single layer of a COSE object. The second set of		layers of a COSE object. The third set of recommendations apply to
	recommendations apply to having multiple implicit algorithms		having implicit algorithms for multiple COSE object constructs.
	identified for multiple layers of a COSE object. The third set of
	recommendations apply to having implicit algorithms for multiple COSE
	object constructs.
	The key words from [RFC2119] are deliberately not used here. This		The key words from [RFC2119] are deliberately not used here. This
	specification can provide recommendations, but it cannot enforce		specification can provide recommendations, but it cannot enforce
	them.		them.
	This set of recommendations applies to the case where an application		This set of recommendations applies to the case where an application
	is distributing a fixed algorithm along with the key information for		is distributing a fixed algorithm along with the key information for
	use in a single COSE object. This normally applies to the smallest		use in a single COSE object. This normally applies to the smallest
	of the COSE objects, specifically COSE_Sign1, COSE_Mac0, and		of the COSE objects, specifically COSE_Sign1, COSE_Mac0, and
	COSE_Encrypt0, but could apply to the other structures as well.		COSE_Encrypt0, but could apply to the other structures as well.
	skipping to change at page 61, line 37 ¶		skipping to change at page 61, line 44 ¶
	different types of messages that have different keys, but where		different types of messages that have different keys, but where
	the keys may be used in a coordinated manner.		the keys may be used in a coordinated manner.
	For these cases, the following additional items need to be		For these cases, the following additional items need to be
	considered:		considered:
	o Applications need to ensure that the multiple contexts stay		o Applications need to ensure that the multiple contexts stay
	associated. If one of the contexts is invalidated for any reason,		associated. If one of the contexts is invalidated for any reason,
	all of the contexts associated with it should also be invalidated.		all of the contexts associated with it should also be invalidated.
	A.2. Counter Signature without Headers
	There is a group of people who want to have a counter signature
	parameter that is directly tied to the value being signed, and thus
	the authenticated and unauthenticated buckets can be removed from the
	message being sent. The focus on this is an even smaller size, as
	all of the information on the process of creating the counter
	signature is implicit rather than being explicitly carried in the
	message. This includes not only the algorithm identifier as
	presented above, but also items such as the key identification, which
	is always external to the signature structure. This means that the
	entities that are doing the validation of the counter signature are
	required to infer which key is to be used from context rather than
	being explicit. One way of doing this would be to presume that all
	data coming from a specific port (or to a specific URL) is to be
	validated by a specific key. (Note that this does not require that
	the key identifier be part of the value signed as it does not serve a
	cryptographic purpose. If the key validates the counter signature,
	then it should be presumed that the entity associated with that key
	produced the signature.)
	When computing the signature for the bare counter signature header,
	the same Sig_structure defined in Section 4.4 is used. The
	sign_protected field is omitted, as there is no protected header
	field in this counter signature header. The value of
	"CounterSignature0" is placed in the context field of the
	Sig_stucture.
	+-------------------+-------+-------+-------+-----------------------+
	| Name | Label | Value | Value | Description |
	| | | Type | | |
	+-------------------+-------+-------+-------+-----------------------+
	| CounterSignature0 | 9 | bstr | | Counter signature |
	| | | | | with implied signer |
	| | | | | and headers |
	+-------------------+-------+-------+-------+-----------------------+
	Table 6: Header Parameter for CounterSignature0
	Appendix B. Two Layers of Recipient Information		Appendix B. Two Layers of Recipient Information
	All of the currently defined recipient algorithm classes only use two		All of the currently defined recipient algorithm classes only use two
	layers of the COSE_Encrypt structure. The first layer is the message		layers of the COSE_Encrypt structure. The first layer is the message
	content, and the second layer is the content key encryption.		content, and the second layer is the content key encryption.
	However, if one uses a recipient algorithm such as the RSA Key		However, if one uses a recipient algorithm such as the RSA Key
	Encapsulation Mechanism (RSA-KEM) (see Appendix A of RSA-KEM		Encapsulation Mechanism (RSA-KEM) (see Appendix A of RSA-KEM
	[RFC5990]), then it makes sense to have three layers of the		[RFC5990]), then it makes sense to have three layers of the
	COSE_Encrypt structure.		COSE_Encrypt structure.
	These layers would be:		These layers would be:
	o Layer 0: The content encryption layer. This layer contains the		o Layer 0: The content encryption layer. This layer contains the
	payload of the message.		payload of the message.
	o Layer 1: The encryption of the CEK by a KEK.		o Layer 1: The encryption of the CEK by a KEK.
End of changes. 109 change blocks.
	322 lines changed or deleted		315 lines changed or added
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