draft-ietf-cose-hash-algs-03.txt		draft-ietf-cose-hash-algs-04.txt
	Network Working Group J. Schaad		Network Working Group J. Schaad
	Internet-Draft August Cellars		Internet-Draft August Cellars
	Intended status: Informational 9 March 2020		Intended status: Informational 29 May 2020
	Expires: 10 September 2020		Expires: 30 November 2020
	CBOR Object Signing and Encryption (COSE): Hash Algorithms		CBOR Object Signing and Encryption (COSE): Hash Algorithms
	draft-ietf-cose-hash-algs-03		draft-ietf-cose-hash-algs-04
	Abstract		Abstract
	The CBOR Object Signing and Encryption (COSE) syntax		The CBOR Object Signing and Encryption (COSE) syntax
	[I-D.ietf-cose-rfc8152bis-struct] does not define any direct methods		[I-D.ietf-cose-rfc8152bis-struct] does not define any direct methods
	for using hash algorithms. There are however circumstances where		for using hash algorithms. There are however circumstances where
	hash algorithms are used: Indirect signatures where the hash of one		hash algorithms are used, such as indirect signatures where the hash
	or more contents are signed. X.509 certificate or other object		of one or more contents are signed, and X.509 certificate or other
	identification by the use of a fingerprint. This document defines a		object identification by the use of a fingerprint. This document
	set of hash algorithms that are identified by COSE Algorithm		defines a set of hash algorithms that are identified by COSE
	Identifiers.		Algorithm Identifiers.
	Contributing to this document		Contributing to this document
	This note is to be removed before publishing as an RFC.		This note is to be removed before publishing as an RFC.
	The source for this draft is being maintained in GitHub. Suggested		The source for this draft is being maintained in GitHub. Suggested
	changes should be submitted as pull requests at https://github.com/		changes should be submitted as pull requests at https://github.com/
	cose-wg/X509 Editorial changes can be managed in GitHub, but any		cose-wg/X509 Editorial changes can be managed in GitHub, but any
	substantial issues need to be discussed on the COSE mailing list.		substantial issues need to be discussed on the COSE mailing list.
	skipping to change at page 1, line 46 ¶		skipping to change at page 1, line 46 ¶
	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 10 September 2020.		This Internet-Draft will expire on 30 November 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 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 (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	skipping to change at page 2, line 28 ¶		skipping to change at page 2, line 28 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Requirements Terminology . . . . . . . . . . . . . . . . 3		1.1. Requirements Terminology . . . . . . . . . . . . . . . . 3
	2. Hash Algorithm Usage . . . . . . . . . . . . . . . . . . . . 3		2. Hash Algorithm Usage . . . . . . . . . . . . . . . . . . . . 3
	2.1. Example CBOR hash structure . . . . . . . . . . . . . . . 4		2.1. Example CBOR hash structure . . . . . . . . . . . . . . . 4
	3. Hash Algorithm Identifiers . . . . . . . . . . . . . . . . . 5		3. Hash Algorithm Identifiers . . . . . . . . . . . . . . . . . 5
	3.1. SHA-1 Hash Algorithm . . . . . . . . . . . . . . . . . . 5		3.1. SHA-1 Hash Algorithm . . . . . . . . . . . . . . . . . . 5
	3.2. SHA-2 Hash Algorithms . . . . . . . . . . . . . . . . . . 6		3.2. SHA-2 Hash Algorithms . . . . . . . . . . . . . . . . . . 6
	3.3. SHAKE Algorithms . . . . . . . . . . . . . . . . . . . . 7		3.3. SHAKE Algorithms . . . . . . . . . . . . . . . . . . . . 8
	4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8		4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
	4.1. COSE Algorithm Registry . . . . . . . . . . . . . . . . . 8		4.1. COSE Algorithm Registry . . . . . . . . . . . . . . . . . 8
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 8		5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
	6. Normative References . . . . . . . . . . . . . . . . . . . . 9		6. Normative References . . . . . . . . . . . . . . . . . . . . 9
	7. Informative References . . . . . . . . . . . . . . . . . . . 10		7. Informative References . . . . . . . . . . . . . . . . . . . 10
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
	1. Introduction		1. Introduction
	The CBOR Object Signing and Encryption (COSE) syntax does not define		The CBOR Object Signing and Encryption (COSE) syntax does not define
	any direct methods for the use of hash algorithms. It also does not		any direct methods for the use of hash algorithms. It also does not
	define a structure syntax that is used to encode a digested object		define a structure syntax that is used to encode a digested object
	structure along the lines of the DigestedData ASN.1 structure in		structure along the lines of the DigestedData ASN.1 structure in
	[CMS]. This omission was intentional as a structure consisting of		[CMS]. This omission was intentional as a structure consisting of
	just a digest identifier, the content, and a digest value does not by		just a digest identifier, the content, and a digest value does not by
	itself provide any strong security service. Additionally, an		itself provide any strong security service. Additionally, an
	skipping to change at page 3, line 36 ¶		skipping to change at page 3, line 36 ¶
	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.
	2. Hash Algorithm Usage		2. Hash Algorithm Usage
	As noted in the previous section, hash functions can be used for a		As noted in the previous section, hash functions can be used for a
	variety of purposes. Some of these purposes require that a hash		variety of purposes. Some of these purposes require that a hash
	function be cryptographically strong, these include direct and		function be cryptographically strong. These include direct and
	indirect signatures. That is, using the hash as part of the		indirect signatures. That is, using the hash as part of the
	signature or using the hash as part of the body to be signed. Other		signature or using the hash as part of the body to be signed. Other
	uses of hash functions do not require the same level of strength.		uses of hash functions do not require the same level of strength.
	This document contains some hash functions that are not designed to		This document contains some hash functions that are not designed to
	be used for cryptographic operations. An application that is using a		be used for cryptographic operations. An application that is using a
	hash function needs to carefully evaluate exactly what hash		hash function needs to carefully evaluate exactly what hash
	properties are needed and which hash functions are going to provide		properties are needed and which hash functions are going to provide
	them. Applications should also make sure that the ability to change		them. Applications should also make sure that the ability to change
	hash functions is part of the base design as cryptographic advances		hash functions is part of the base design as cryptographic advances
	are sure to reduce the strength of a hash function.		are sure to reduce the strength of a hash function.
	A hash function is a map from one, normally large, bit string to a		A hash function is a map from one, normally large, bit string to a
	second, usually smaller, bit string. There are going to be		second, usually smaller, bit string. There are going to be
	collisions by a hash function, the trick is to make sure that it is		collisions by a hash function. The trick is to make sure that it is
	difficult to find two values that are going to map to the same output		difficult to find two values that are going to map to the same output
	value. The standard "Collision Attack" is one where an attacker can		value. The standard "Collision Attack" is one where an attacker can
	find two different messages that have the same hash value. If a		find two different messages that have the same hash value. If a
	collision attack exists, then the function SHOULD NOT be used for a		collision attack exists, then the function SHOULD NOT be used for a
	cryptographic purpose. The only reason why such a hash function is		cryptographic purpose. The only reason why such a hash function is
	used is when there is absolutely no other choice (e.g. a Hardware		used is when there is absolutely no other choice (e.g. a Hardware
	Security Module (HSM) that cannot be replaced), and only after		Security Module (HSM) that cannot be replaced), and only after
	looking at the possible security issues. Cryptographic purposes		looking at the possible security issues. Cryptographic purposes
	would include the creation of signatures or the use of hashes for		would include the creation of signatures or the use of hashes for
	indirect signatures. These functions may still be usable for non-		indirect signatures. These functions may still be usable for non-
	skipping to change at page 4, line 46 ¶		skipping to change at page 4, line 46 ¶
	[COSE] did not provide a default structure for holding a hash value		[COSE] did not provide a default structure for holding a hash value
	not only because no separate hash algorithms were defined, but		not only because no separate hash algorithms were defined, but
	because how the structure is setup is frequently application		because how the structure is setup is frequently application
	specific. There are four fields that are often included as part of a		specific. There are four fields that are often included as part of a
	hash structure:		hash structure:
	* The hash algorithm identifier.		* The hash algorithm identifier.
	* The hash value.		* The hash value.
	* A pointer to the value that was hashed, this could be a pointer to		* A pointer to the value that was hashed. this could be a pointer
	a file, an object that can be obtained from the network, or a		to a file, an object that can be obtained from the network, or a
	pointer to someplace in the message, or something very application		pointer to someplace in the message, or something very application
	specific.		specific.
	* Additional data, this can be something as simple as a random value		* Additional data, this can be something as simple as a random value
	to make finding hash collisions slightly harder (as the value		to make finding hash collisions slightly harder (as the value
	handed to the application cannot have been selected to have a		handed to the application cannot have been selected to have a
	collision), or as complicated as a set of processing instructions		collision), or as complicated as a set of processing instructions
	that are used with the object that is pointed to. The additional		that are used with the object that is pointed to. The additional
	data can be dealt with in a number of ways, prepending or		data can be dealt with in a number of ways, prepending or
	appending to the content, but it is strongly suggested to it		appending to the content, but it is strongly suggested to it
	skipping to change at page 5, line 26 ¶		skipping to change at page 5, line 26 ¶
	An example of a structure which permits all of the above fields to		An example of a structure which permits all of the above fields to
	exist would look like the following.		exist would look like the following.
	COSE_Hash_V = (		COSE_Hash_V = (
	1 : int / tstr, # Algorithm identifier		1 : int / tstr, # Algorithm identifier
	2 : bstr, # Hash value		2 : bstr, # Hash value
	3 : tstr ?, # Location of object hashed		3 : tstr ?, # Location of object hashed
	4 : any ? # object containing other details and things		4 : any ? # object containing other details and things
	)		)
	An alternate structure that could be used for situations where one is		An alternative structure that could be used for situations where one
	searching a group of objects for a match. In this case, the location		is searching a group of objects for a match. In this case, the
	would not be needed and adding extra data to the hash would be		location would not be needed and adding extra data to the hash would
	counterproductive. This results in a structure that looks like this:		be counterproductive. This results in a structure that looks like
			this:
	COSE_Hash_Find = [		COSE_Hash_Find = [
	hashAlg : int / tstr,		hashAlg : int / tstr,
	hashValue : bstr		hashValue : bstr
	]		]
	3. Hash Algorithm Identifiers		3. Hash Algorithm Identifiers
	3.1. SHA-1 Hash Algorithm		3.1. SHA-1 Hash Algorithm
	skipping to change at page 6, line 42 ¶		skipping to change at page 6, line 49 ¶
	and some of the trade-offs involved.		and some of the trade-offs involved.
	* *SHA-256/64* provides a truncated hash. The length of the		* *SHA-256/64* provides a truncated hash. The length of the
	truncation is designed to allow for smaller transmission size.		truncation is designed to allow for smaller transmission size.
	The trade-off is that the odds that a collision will occur		The trade-off is that the odds that a collision will occur
	increase proportionally. Locations that use this hash function		increase proportionally. Locations that use this hash function
	need either to analysis the potential problems with having a		need either to analysis the potential problems with having a
	collision occur, or where the only function of the hash is to		collision occur, or where the only function of the hash is to
	narrow the possible choices.		narrow the possible choices.
	The latter is the case for [I-D.ietf-cose-x509], the hash value is		The latter is the case for [I-D.ietf-cose-x509]. The hash value
	used to select possible certificates and, if there are multiple		is used to select possible certificates and, if there are multiple
	choices then, each choice can be tested by using the public key.		choices then, each choice can be tested by using the public key.
	* *SHA-256* is probably the most common hash function used		* *SHA-256* is probably the most common hash function used
	currently. SHA-256 is an efficient hash algorithm for 32-bit		currently. SHA-256 is an efficient hash algorithm for 32-bit
	hardware.		hardware.
	* *SHA-384* and *SHA-512* hash functions are efficient for 64-bit		* *SHA-384* and *SHA-512* hash functions are efficient for 64-bit
	hardware.		hardware.
	* *SHA-512/256* provides a hash function that runs more efficiently		* *SHA-512/256* provides a hash function that runs more efficiently
	on 64-bit hardware, but offers the same security levels as SHA-		on 64-bit hardware, but offers the same security levels as SHA-
	256.		256.
	The COSE capabilities for these algorithms is an empty array.		The COSE capabilities array for these algorithms is empty.
	+-----------+-----+-----------+--------------+---------+------------+		+-----------+-----+-----------+--------------+---------+------------+
	| Name |Value|Description| Capabilities |Reference|Recommended |		| Name |Value|Description| Capabilities |Reference|Recommended |
	+===========+=====+===========+==============+=========+============+		+===========+=====+===========+==============+=========+============+
	|SHA-256/64 |TBD1 | SHA-2 | [] | [This |Filter Only |		|SHA-256/64 |TBD1 | SHA-2 | [] | [This |Filter Only |
	| | | 256-bit | |Document]| |		| | | 256-bit | |Document]| |
	| | | Hash | | | |		| | | Hash | | | |
	| | | truncated | | | |		| | | truncated | | | |
	| | |to 64-bits | | | |		| | |to 64-bits | | | |
	+-----------+-----+-----------+--------------+---------+------------+		+-----------+-----+-----------+--------------+---------+------------+
	skipping to change at page 7, line 43 ¶		skipping to change at page 8, line 7 ¶
	| | | 512-bit | |Document]| |		| | | 512-bit | |Document]| |
	| | | Hash | | | |		| | | Hash | | | |
	| | | truncated | | | |		| | | truncated | | | |
	| | |to 256-bits| | | |		| | |to 256-bits| | | |
	+-----------+-----+-----------+--------------+---------+------------+		+-----------+-----+-----------+--------------+---------+------------+
	Table 2: SHA-2 Hash Algorithms		Table 2: SHA-2 Hash Algorithms
	3.3. SHAKE Algorithms		3.3. SHAKE Algorithms
	The family SHA-3 hash algorithms [FIPS-202] was the result of a		The family of SHA-3 hash algorithms [FIPS-202] was the result of a
	competition run by NIST. The pair of algorithms known as SHAKE-128		competition run by NIST. The pair of algorithms known as SHAKE-128
	and SHAKE-256 are the instances of SHA-3 that are currently being		and SHAKE-256 are the instances of SHA-3 that are currently being
	standardized in the IETF.		standardized in the IETF.
	The SHA-3 hash algorithms have a significantly different structure		The SHA-3 hash algorithms have a significantly different structure
	than the SHA-2 hash algorithms. One of the benefits of this		than the SHA-2 hash algorithms. One of the benefits of this
	differences is that when computing a shorter SHAKE hash value, the		differences is that when computing a shorter SHAKE hash value, the
	value is not a prefix of the result of computing the longer hash.		value is not a prefix of the result of computing the longer hash.
	Unlike the SHA-2 hash functions, no algorithm identifier is created		Unlike the SHA-2 hash functions, no algorithm identifier is created
	for shorter lengths. Applications can specify a minimum length for		for shorter lengths. Applications can specify a minimum length for
	any hash function. A validator can infer the actual length from the		any hash function. A validator can infer the actual length from the
	hash value in these cases.		hash value in these cases.
	The COSE capabilities for these algorithms is an empty array.		The COSE capabilities array for these algorithms is empty.
	+--------+-----+-------------+--------------+---------+-------------+		+--------+-----+-------------+--------------+---------+-------------+
	| Name |Value| Description | Capabilities |Reference| Recommended |		| Name |Value| Description | Capabilities |Reference| Recommended |
	+========+=====+=============+==============+=========+=============+		+========+=====+=============+==============+=========+=============+
	|SHAKE128|TBD10|128-bit SHAKE| [] | [This | Yes |		|SHAKE128|TBD10|128-bit SHAKE| [] | [This | Yes |
	| | | | |Document]| |		| | | | |Document]| |
	+--------+-----+-------------+--------------+---------+-------------+		+--------+-----+-------------+--------------+---------+-------------+
	|SHAKE256|TBD11|256-bit SHAKE| [] | [This | Yes |		|SHAKE256|TBD11|256-bit SHAKE| [] | [This | Yes |
	| | | | |Document]| |		| | | | |Document]| |
	+--------+-----+-------------+--------------+---------+-------------+		+--------+-----+-------------+--------------+---------+-------------+
	Table 3: SHAKE Hash Functions		Table 3: SHAKE Hash Functions
	4. IANA Considerations		4. IANA Considerations
			The IANA actions in [I-D.ietf-cose-rfc8152bis-struct] and
			[I-D.ietf-cose-rfc8152bis-algs] need to be executed before the
			actions in this document. Where early allocation of data points has
			been made, these should be preseved.
	4.1. COSE Algorithm Registry		4.1. COSE Algorithm Registry
	IANA is requested to register the following algorithms in the "COSE		IANA is requested to register the following algorithms in the "COSE
	Algorithms" registry.		Algorithms" registry.
	* The SHA-1 hash function found in Table 1.		* The SHA-1 hash function found in Table 1.
	* The set of SHA-2 hash functions found in Table 2.		* The set of SHA-2 hash functions found in Table 2.
	* The set of SHAKE hash functions found in Table 3.		* The set of SHAKE hash functions found in Table 3.
	Many of the hash values produced are relatively long and as such the		Many of the hash values produced are relatively long and as such the
	use of a two byte algorithm identifier seems reasonable. SHA-1 is		use of a two byte algorithm identifier seems reasonable. SHA-1 is
	tagged as deprecated and thus a longer algorithm identifier is		tagged as deprecated and thus a longer algorithm identifier is
	appropriate even though it is a shorter hash value.		appropriate even though it is a shorter hash value.
	In addition, IANA is to add the value of 'Filter Only' to the set of		In addition, IANA is to add the value of 'Filter Only' to the set of
	legal values for the 'Recommended' column. This value is only to be		legal values for the 'Recommended' column. This value is only to be
	used for hash functions and indicates that it is not to be used for		used for hash functions and indicates that it is not to be used for
	purposes which require collision resistance.		purposes which require collision resistance. IANA is requested to
			add this document to the reference section for this table due to this
			addition.
	5. Security Considerations		5. Security Considerations
	The security considerations have already been called out as part of		Protocols need to perform a careful analysis of the properties of a
	the previous text. The following issues need to be dealt with:		hash function that are needed and how they map onto the possible
			attacks. In particular, one needs to distinguish between those uses
	* Protocols need to perform a careful analysis of the properties of		that need the cryptographic properties, i.e. collision resistance,
	a hash function that are needed and how they map onto the possible		and properties that correspond to possible object identification.
	attacks. In particular, one needs to distinguish between those		The different attacks correspond to who or what is being protected:
	uses that need the cryptographic properties, i.e. collision		is it the originator that is the attacker or a third party? This is
	resistance, and properties that correspond to possible object		the difference between collision resistance and second pre-image
	identification. The different attacks correspond to who or what		resistance. As a general rule, longer hash values are "better" than
	is being protected, is it the originator that is the attacker or a		short ones, but trade-offs of transmission size, timeliness, and
	third party? This is the difference between collision resistance		security all need to be included as part of this analysis. In many
	and second pre-image resistance. As a general rule, longer hash		cases the value being hashed is a public value, as such pre-image
	values are "better" than short ones, but trade-offs of		resistance is not part of this analysis.
	transmission size, timeliness, and security all need to be
	included as part of this analysis. In many cases the value being
	hashed is a public value, as such pre-image resistance is not part
	of this analysis.
	* Algorithm agility needs to be considered a requirement for any use		Algorithm agility needs to be considered a requirement for any use of
	of hash functions. As with any cryptographic function, hash		hash functions. As with any cryptographic function, hash functions
	functions are under constant attack and the strength of hash		are under constant attack and the strength of hash algorithms will be
	algorithms will be reduced over time.		reduced over time.
	6. Normative References		6. Normative References
	[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>.
	[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>.
	[I-D.ietf-cose-rfc8152bis-struct]		[I-D.ietf-cose-rfc8152bis-struct]
	Schaad, J., "CBOR Object Signing and Encryption (COSE):		Schaad, J., "CBOR Object Signing and Encryption (COSE):
	Structures and Process", Work in Progress, Internet-Draft,		Structures and Process", Work in Progress, Internet-Draft,
	draft-ietf-cose-rfc8152bis-struct-07, 17 November 2019,		draft-ietf-cose-rfc8152bis-struct-09, 14 May 2020,
	<https://tools.ietf.org/html/draft-ietf-cose-rfc8152bis-		<https://tools.ietf.org/html/draft-ietf-cose-rfc8152bis-
	struct-07>.		struct-09>.
	[FIPS-180-4]		[FIPS-180-4]
	National Institute of Standards and Technology, "Secure		National Institute of Standards and Technology, "Secure
	Hash Standard", FIPS PUB 180-4, August 2015.		Hash Standard", FIPS PUB 180-4, August 2015.
	[FIPS-202] National Institute of Standards and Technology, "SHA-3		[FIPS-202] National Institute of Standards and Technology, "SHA-3
	Standard: Permutation-Based Hash and Extendable-Output		Standard: Permutation-Based Hash and Extendable-Output
	Functions", FIPS PUB 202, August 2015.		Functions", FIPS PUB 202, August 2015.
	[COSE] Schaad, J., "CBOR Object Signing and Encryption (COSE)",		[COSE] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
	skipping to change at page 10, line 19 ¶		skipping to change at page 10, line 36 ¶
	[CMS] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,		[CMS] 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>.
	[ESS] Hoffman, P., Ed., "Enhanced Security Services for S/MIME",		[ESS] Hoffman, P., Ed., "Enhanced Security Services for S/MIME",
	RFC 2634, DOI 10.17487/RFC2634, June 1999,		RFC 2634, DOI 10.17487/RFC2634, June 1999,
	<https://www.rfc-editor.org/info/rfc2634>.		<https://www.rfc-editor.org/info/rfc2634>.
	[I-D.ietf-cose-x509]		[I-D.ietf-cose-x509]
	Schaad, J., "CBOR Object Signing and Encryption (COSE):		Schaad, J., "CBOR Object Signing and Encryption (COSE):
	Headers for carrying and referencing X.509 certificates",		Header parameters for carrying and referencing X.509
	Work in Progress, Internet-Draft, draft-ietf-cose-x509-05,		certificates", Work in Progress, Internet-Draft, draft-
	4 November 2019,		ietf-cose-x509-06, 9 March 2020,
	<https://tools.ietf.org/html/draft-ietf-cose-x509-05>.		<https://tools.ietf.org/html/draft-ietf-cose-x509-06>.
	[RFC3174] Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm 1		[RFC3174] Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm 1
	(SHA1)", RFC 3174, DOI 10.17487/RFC3174, September 2001,		(SHA1)", RFC 3174, DOI 10.17487/RFC3174, September 2001,
	<https://www.rfc-editor.org/info/rfc3174>.		<https://www.rfc-editor.org/info/rfc3174>.
	[RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security		[RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security
	Considerations for the SHA-0 and SHA-1 Message-Digest		Considerations for the SHA-0 and SHA-1 Message-Digest
	Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,		Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,
	<https://www.rfc-editor.org/info/rfc6194>.		<https://www.rfc-editor.org/info/rfc6194>.
			[I-D.ietf-cose-rfc8152bis-algs]
			Schaad, J., "CBOR Object Signing and Encryption (COSE):
			Initial Algorithms", Work in Progress, Internet-Draft,
			draft-ietf-cose-rfc8152bis-algs-08, 14 May 2020,
			<https://tools.ietf.org/html/draft-ietf-cose-rfc8152bis-
			algs-08>.
	[SHA-1-collision]		[SHA-1-collision]
	Stevens, M., Bursztein, E., Karpman, P., Albertini, A.,		Stevens, M., Bursztein, E., Karpman, P., Albertini, A.,
	and Y. Markov, "The first collision for full SHA-1",		and Y. Markov, "The first collision for full SHA-1",
	February 2017,		February 2017,
	<https://shattered.io/static/shattered.pdf>.		<https://shattered.io/static/shattered.pdf>.
	Author's Address		Author's Address
	Jim Schaad		Jim Schaad
	August Cellars		August Cellars
End of changes. 23 change blocks.
	53 lines changed or deleted		64 lines changed or added
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