draft-ietf-rats-eat-02.txt   draft-ietf-rats-eat-03.txt 
RATS Working Group G. Mandyam RATS Working Group G. Mandyam
Internet-Draft Qualcomm Technologies Inc. Internet-Draft Qualcomm Technologies Inc.
Intended status: Standards Track L. Lundblade Intended status: Standards Track L. Lundblade
Expires: July 12, 2020 Security Theory LLC Expires: August 23, 2020 Security Theory LLC
M. Ballesteros M. Ballesteros
J. O'Donoghue J. O'Donoghue
Qualcomm Technologies Inc. Qualcomm Technologies Inc.
January 09, 2020 February 20, 2020
The Entity Attestation Token (EAT) The Entity Attestation Token (EAT)
draft-ietf-rats-eat-02 draft-ietf-rats-eat-03
Abstract Abstract
An Entity Attestation Token (EAT) provides a signed (attested) set of An Entity Attestation Token (EAT) provides a signed (attested) set of
claims that describe state and characteristics of an entity, claims that describe state and characteristics of an entity,
typically a device like a phone or an IoT device. These claims are typically a device like a phone or an IoT device. These claims are
used by a relying party to determine how much it wishes to trust the used by a relying party to determine how much it wishes to trust the
entity. entity.
An EAT is either a CWT or JWT with some attestation-oriented claims. An EAT is either a CWT or JWT with some attestation-oriented claims.
skipping to change at page 1, line 45 skipping to change at page 1, line 45
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This Internet-Draft will expire on July 12, 2020. This Internet-Draft will expire on August 23, 2020.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. CDDL, CWT and JWT . . . . . . . . . . . . . . . . . . . . 4 1.1. CDDL, CWT and JWT . . . . . . . . . . . . . . . . . . . . 4
1.2. Entity Overview . . . . . . . . . . . . . . . . . . . . . 4 1.2. Entity Overview . . . . . . . . . . . . . . . . . . . . . 5
1.3. EAT Operating Models . . . . . . . . . . . . . . . . . . 5 1.3. EAT Operating Models . . . . . . . . . . . . . . . . . . 5
1.4. What is Not Standardized . . . . . . . . . . . . . . . . 6 1.4. What is Not Standardized . . . . . . . . . . . . . . . . 6
1.4.1. Transmission Protocol . . . . . . . . . . . . . . . . 6 1.4.1. Transmission Protocol . . . . . . . . . . . . . . . . 6
1.4.2. Signing Scheme . . . . . . . . . . . . . . . . . . . 7 1.4.2. Signing Scheme . . . . . . . . . . . . . . . . . . . 7
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. The Claims Information Model . . . . . . . . . . . . . . . . 8 3. The Claims . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Token ID Claim (cti and jti) . . . . . . . . . . . . . . 8 3.1. Token ID Claim (cti and jti) . . . . . . . . . . . . . . 8
3.2. Timestamp claim (iat) . . . . . . . . . . . . . . . . . . 8 3.2. Timestamp claim (iat) . . . . . . . . . . . . . . . . . . 9
3.3. Nonce Claim (nonce) . . . . . . . . . . . . . . . . . . . 8 3.3. Nonce Claim (nonce) . . . . . . . . . . . . . . . . . . . 9
3.3.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 9 3.3.1. nonce CDDL . . . . . . . . . . . . . . . . . . . . . 9
3.4. Universal Entity ID Claim (ueid) . . . . . . . . . . . . 9 3.4. Universal Entity ID Claim (ueid) . . . . . . . . . . . . 9
3.4.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 11 3.4.1. ueid CDDL . . . . . . . . . . . . . . . . . . . . . . 12
3.5. Origination Claim (origination) . . . . . . . . . . . . . 11 3.5. Origination Claim (origination) . . . . . . . . . . . . . 12
3.5.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 12 3.5.1. origination CDDL . . . . . . . . . . . . . . . . . . 12
3.6. OEM Identification by IEEE (oemid) . . . . . . . . . . . 12 3.6. OEM Identification by IEEE (oemid) . . . . . . . . . . . 12
3.6.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 12 3.6.1. oemid CDDL . . . . . . . . . . . . . . . . . . . . . 13
3.7. The Security Level Claim (security_level) . . . . . . . . 12 3.7. The Security Level Claim (security-level) . . . . . . . . 13
3.7.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 13 3.7.1. security-level CDDL . . . . . . . . . . . . . . . . . 14
3.8. Secure Boot and Debug Enable State Claims (boot_state) . 13 3.8. Secure Boot and Debug Enable State Claims (boot-state) . 14
3.8.1. Secure Boot Enabled . . . . . . . . . . . . . . . . . 14 3.8.1. Secure Boot Enabled . . . . . . . . . . . . . . . . . 14
3.8.2. Debug Disabled . . . . . . . . . . . . . . . . . . . 14 3.8.2. Debug Disabled . . . . . . . . . . . . . . . . . . . 15
3.8.3. Debug Disabled Since Boot . . . . . . . . . . . . . . 14 3.8.3. Debug Disabled Since Boot . . . . . . . . . . . . . . 15
3.8.4. Debug Permanent Disable . . . . . . . . . . . . . . . 14 3.8.4. Debug Permanent Disable . . . . . . . . . . . . . . . 15
3.8.5. Debug Full Permanent Disable . . . . . . . . . . . . 14 3.8.5. Debug Full Permanent Disable . . . . . . . . . . . . 15
3.8.6. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 14 3.8.6. boot-state CDDL . . . . . . . . . . . . . . . . . . . 15
3.9. The Location Claim (location) . . . . . . . . . . . . . . 15 3.9. The Location Claim (location) . . . . . . . . . . . . . . 15
3.9.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 15 3.9.1. location CDDL . . . . . . . . . . . . . . . . . . . . 16
3.10. The Age Claim (age) . . . . . . . . . . . . . . . . . . . 15 3.10. The Age Claim (age) . . . . . . . . . . . . . . . . . . . 16
3.11. The Uptime Claim (uptime) . . . . . . . . . . . . . . . . 15 3.10.1. age CDDL . . . . . . . . . . . . . . . . . . . . . . 16
3.11.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 15 3.11. The Uptime Claim (uptime) . . . . . . . . . . . . . . . . 16
3.12. Nested EATs, the EAT Claim (nested_eat) . . . . . . . . . 16 3.11.1. uptime CDDL . . . . . . . . . . . . . . . . . . . . 16
3.12.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 16 3.12. The Submods Part of a Token (submods) . . . . . . . . . . 17
3.13. The Submods Claim (submods) . . . . . . . . . . . . . . . 16 3.12.1. Two Types of Submodules . . . . . . . . . . . . . . 17
3.13.1. The submod_name Claim . . . . . . . . . . . . . . . 16 3.12.1.1. Non-token Submodules . . . . . . . . . . . . . . 17
3.13.2. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 17 3.12.1.2. Nested EATs . . . . . . . . . . . . . . . . . . 17
4. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.12.2. No Inheritance . . . . . . . . . . . . . . . . . . . 18
4.1. Common CDDL Types . . . . . . . . . . . . . . . . . . . . 17 3.12.3. Security Levels . . . . . . . . . . . . . . . . . . 18
4.2. CDDL for CWT-defined Claims . . . . . . . . . . . . . . . 17 3.12.4. Submodule Names . . . . . . . . . . . . . . . . . . 18
4.3. JSON . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.12.5. submods CDDL . . . . . . . . . . . . . . . . . . . . 18
4.3.1. JSON Labels . . . . . . . . . . . . . . . . . . . . . 18 4. Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.3.2. JSON Interoperability . . . . . . . . . . . . . . . . 19 4.1. Common CDDL Types . . . . . . . . . . . . . . . . . . . . 19
4.4. CBOR . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.2. CDDL for CWT-defined Claims . . . . . . . . . . . . . . . 19
4.4.1. Labels . . . . . . . . . . . . . . . . . . . . . . . 19 4.3. JSON . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.4.2. CBOR Interoperability . . . . . . . . . . . . . . . . 20 4.3.1. JSON Labels . . . . . . . . . . . . . . . . . . . . . 19
4.5. Collected CDDL . . . . . . . . . . . . . . . . . . . . . 21 4.3.2. JSON Interoperability . . . . . . . . . . . . . . . . 20
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 4.4. CBOR . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1. Reuse of CBOR Web Token (CWT) Claims Registry . . . . . . 22 4.4.1. CBOR Labels . . . . . . . . . . . . . . . . . . . . . 20
5.1.1. Claims Registered by This Document . . . . . . . . . 22 4.4.2. CBOR Interoperability . . . . . . . . . . . . . . . . 21
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 23 4.5. Collected CDDL . . . . . . . . . . . . . . . . . . . . . 22
6.1. UEID Privacy Considerations . . . . . . . . . . . . . . . 23 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
7. Security Considerations . . . . . . . . . . . . . . . . . . . 24 5.1. Reuse of CBOR Web Token (CWT) Claims Registry . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 5.1.1. Claims Registered by This Document . . . . . . . . . 23
8.1. Normative References . . . . . . . . . . . . . . . . . . 24 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 24
8.2. Informative References . . . . . . . . . . . . . . . . . 25 6.1. UEID Privacy Considerations . . . . . . . . . . . . . . . 24
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 27 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
A.1. Very Simple EAT . . . . . . . . . . . . . . . . . . . . . 27 7.1. Key Provisioning . . . . . . . . . . . . . . . . . . . . 25
A.2. Example with Submodules, Nesting and Security Levels . . 27 7.1.1. Transmission of Key Material . . . . . . . . . . . . 25
Appendix B. Changes from Previous Drafts . . . . . . . . . . . . 28 7.2. Transport Security . . . . . . . . . . . . . . . . . . . 25
B.1. From draft-mandyam-rats-eat-00 . . . . . . . . . . . . . 28 7.3. Multiple EAT Consumers . . . . . . . . . . . . . . . . . 26
B.2. From draft-ietf-rats-eat-01 . . . . . . . . . . . . . . . 28 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28 8.1. Normative References . . . . . . . . . . . . . . . . . . 26
8.2. Informative References . . . . . . . . . . . . . . . . . 28
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 30
A.1. Very Simple EAT . . . . . . . . . . . . . . . . . . . . . 30
A.2. Example with Submodules, Nesting and Security Levels . . 30
Appendix B. UEID Design Rationale . . . . . . . . . . . . . . . 30
B.1. Collision Probability . . . . . . . . . . . . . . . . . . 30
B.2. No Use of UUID . . . . . . . . . . . . . . . . . . . . . 33
Appendix C. Changes from Previous Drafts . . . . . . . . . . . . 34
C.1. From draft-rats-eat-01 . . . . . . . . . . . . . . . . . 34
C.2. From draft-mandyam-rats-eat-00 . . . . . . . . . . . . . 34
C.3. From draft-ietf-rats-eat-01 . . . . . . . . . . . . . . . 34
C.4. From draft-ietf-rats-eat-02 . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
1. Introduction 1. Introduction
Remote device attestation is a fundamental service that allows a Remote device attestation is a fundamental service that allows a
remote device such as a mobile phone, an Internet-of-Things (IoT) remote device such as a mobile phone, an Internet-of-Things (IoT)
device, or other endpoint to prove itself to a relying party, a device, or other endpoint to prove itself to a relying party, a
server or a service. This allows the relying party to know some server or a service. This allows the relying party to know some
characteristics about the device and decide whether it trusts the characteristics about the device and decide whether it trusts the
device. device.
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CWT Claims Set. The CBOR map or JSON object that contains the claims CWT Claims Set. The CBOR map or JSON object that contains the claims
conveyed by the CWT or JWT. conveyed by the CWT or JWT.
Attestation Key Material (AKM). The key material used to sign the Attestation Key Material (AKM). The key material used to sign the
EAT token. If it is done symmetrically with HMAC, then this is a EAT token. If it is done symmetrically with HMAC, then this is a
simple symmetric key. If it is done with ECC, such as an IEEE simple symmetric key. If it is done with ECC, such as an IEEE
DevID [IDevID], then this is the private part of the EC key pair. DevID [IDevID], then this is the private part of the EC key pair.
If ECDAA is used, (e.g., as used by Enhanced Privacy ID, i.e. If ECDAA is used, (e.g., as used by Enhanced Privacy ID, i.e.
EPID) then it is the key material needed for ECDAA. EPID) then it is the key material needed for ECDAA.
3. The Claims Information Model 3. The Claims
This section describes new claims defined for attestation. It also This section describes new claims defined for attestation. It also
mentions several claims defined by CWT and JWT that are particularly mentions several claims defined by CWT and JWT that are particularly
important for EAT. important for EAT.
Note also: * Any claim defined for CWT or JWT may be used in an EAT Note also: * Any claim defined for CWT or JWT may be used in an EAT
including those in the CWT [IANA.CWT.Claims] and JWT IANA including those in the CWT [IANA.CWT.Claims] and JWT IANA
[IANA.JWT.Claims] claims registries. [IANA.JWT.Claims] claims registries.
o All claims are optional o All claims are optional
o No claims are mandatory o No claims are mandatory
o All claims that are not understood by implementations MUST be o All claims that are not understood by implementations MUST be
ignored ignored
CDDL along with text descriptions is used to define the information CDDL along with text descriptions is used to define each claim
model. Each claim is defined as a CDDL group (the group is a general indepdent of encoding. Each claim is defined as a CDDL group (the
aggregation and type definition feature of CDDL). In the data model, group is a general aggregation and type definition feature of CDDL).
described in the Section 4, the CDDL groups turn into CBOR map In the encoding section Section 4, the CDDL groups turn into CBOR map
entries and JSON name/value pairs. entries and JSON name/value pairs.
3.1. Token ID Claim (cti and jti) 3.1. Token ID Claim (cti and jti)
CWT defines the "cti" claim. JWT defines the "jti" claim. These are CWT defines the "cti" claim. JWT defines the "jti" claim. These are
equivalent to each other in EAT and carry a unique token identifier equivalent to each other in EAT and carry a unique token identifier
as they do in JWT and CWT. They may be used to defend against re use as they do in JWT and CWT. They may be used to defend against re use
of the token but are distinct from the nonce that is used by the of the token but are distinct from the nonce that is used by the
relying party to guarantee freshness and defend against replay. relying party to guarantee freshness and defend against replay.
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This documents the nonce claim for registration in the IANA CWT This documents the nonce claim for registration in the IANA CWT
claims registry. This is equivalent to the JWT nonce claim that is claims registry. This is equivalent to the JWT nonce claim that is
already registered. already registered.
The nonce must be at least 8 bytes (64 bits) as fewer are unlikely to The nonce must be at least 8 bytes (64 bits) as fewer are unlikely to
be secure. A maximum of 64 bytes is set to limit the memory a be secure. A maximum of 64 bytes is set to limit the memory a
constrained implementation uses. This size range is not set for the constrained implementation uses. This size range is not set for the
already-registered JWT nonce, but it should follow this size already-registered JWT nonce, but it should follow this size
recommendation when used in an EAT. recommendation when used in an EAT.
3.3.1. CDDL Multiple nonces are allowed to accommodate multistage verification
and consumption.
nonce_claim = ( 3.3.1. nonce CDDL
nonce => bstr .size (8..64)
nonce-type = [ + bstr .size (8..64) ]
nonce-claim = (
nonce => nonce-type
) )
3.4. Universal Entity ID Claim (ueid) 3.4. Universal Entity ID Claim (ueid)
UEID's identify individual manufactured entities / devices such as a UEID's identify individual manufactured entities / devices such as a
mobile phone, a water meter, a Bluetooth speaker or a networked mobile phone, a water meter, a Bluetooth speaker or a networked
security camera. It may identify the entire device or a submodule or security camera. It may identify the entire device or a submodule or
subsystem. It does not identify types, models or classes of devices. subsystem. It does not identify types, models or classes of devices.
It is akin to a serial number, though it does not have to be It is akin to a serial number, though it does not have to be
sequential. sequential.
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different industries made by two different manufacturers in two different industries made by two different manufacturers in two
different countries should have the same UEID (if they are not global different countries should have the same UEID (if they are not global
and universal in this way, then relying parties receiving them will and universal in this way, then relying parties receiving them will
have to track other characteristics of the device to keep devices have to track other characteristics of the device to keep devices
distinct between manufacturers). distinct between manufacturers).
There are privacy considerations for UEID's. See Section 6.1. There are privacy considerations for UEID's. See Section 6.1.
The UEID should be permanent. It should never change for a given The UEID should be permanent. It should never change for a given
device / entity. In addition, it should not be reprogrammable. device / entity. In addition, it should not be reprogrammable.
UEID's are variable length. The recommended maximum is 33 bytes (1 UEID's are variable length. All implementations MUST be able to
type byte and 256 bits). The recommended minimum is 17 bytes (1 type receive UEID's that are 33 bytes long (1 type byte and 256 bits).
and 128 bits) because fewer bytes endanger the universal uniqueness. The recommended maximum sent is also 33 bytes.
When the entity constructs the UEID, the first byte is a type and the When the entity constructs the UEID, the first byte is a type and the
following bytes the ID for that type. Several types are allowed to following bytes the ID for that type. Several types are allowed to
accommodate different industries and different manufacturing accommodate different industries and different manufacturing
processes and to give options to avoid paying fees for certain types processes and to give options to avoid paying fees for certain types
of manufacturer registrations. of manufacturer registrations.
Creation of new types requires a Standards Action [RFC8126]. Creation of new types requires a Standards Action [RFC8126].
+------+--------+---------------------------------------------------+ +------+------+-----------------------------------------------------+
| Type | Type | Specification | | Type | Type | Specification |
| Byte | Name | | | Byte | Name | |
+------+--------+---------------------------------------------------+ +------+------+-----------------------------------------------------+
| 0x01 | RAND | This is a 128- to 256-bit random number generated | | 0x01 | RAND | This is a 128, 192 or 256 bit random number |
| | | once and stored in the device. This may be | | | | generated once and stored in the device. This may |
| | | constructed by concatenating enough identifiers | | | | be constructed by concatenating enough identifiers |
| | | to be universally unique and then feeding the | | | | to make up an equivalent number of random bits and |
| | | concatenation through a cryptographic hash | | | | then feeding the concatenation through a |
| | | function. It may also be a cryptographic quality | | | | cryptographic hash function. It may also be a |
| | | random number generate once at the beginning of | | | | cryptographic quality random number generated once |
| | | the life of the device and stored. | | | | at the beginning of the life of the device and |
| 0x02 | IEEE | This makes use of the IEEE company identification | | | | stored. It may not be smaller than 128 bits. |
| | EUI | registry. An EUI is made up of an OUI and OUI-36 | | 0x02 | IEEE | This makes use of the IEEE company identification |
| | | or a CID, different registered company | | | EUI | registry. An EUI is either an EUI-48, EUI-60 or |
| | | identifiers, and some unique per-device | | | | EUI-64 and made up of an OUI, OUI-36 or a CID, |
| | | identifier. EUIs are often the same as or similar | | | | different registered company identifiers, and some |
| | | to MAC addresses. (Note that while devices with | | | | unique per-device identifier. EUIs are often the |
| | | multiple network interfaces may have multiple MAC | | | | same as or similar to MAC addresses. This type |
| | | addresses, there is only one UEID for a device) | | | | includes MAC-48, an obsolete name for EUI-48. (Note |
| | | TODO: normative references to IEEE. | | | | that while devices with multiple network interfaces |
| 0x03 | IMEI | This is a 14-digit identifier consisting of an | | | | may have multiple MAC addresses, there is only one |
| | | 8-digit Type Allocation Code and a 6-digit serial | | | | UEID for a device) [IEEE.802-2001], [OUI.Guide] |
| | | number allocated by the manufacturer, which SHALL | | 0x03 | IMEI | This is a 14-digit identifier consisting of an |
| | | be encoded as a binary integer over 48 bits. The | | | | 8-digit Type Allocation Code and a 6-digit serial |
| | | IMEI value encoded SHALL NOT include Luhn | | | | number allocated by the manufacturer, which SHALL |
| | | checksum or SVN information. | | | | be encoded as a binary integer over 48 bits. The |
| 0x04 | EUI-48 | This is a 48-bit identifier formed by | | | | IMEI value encoded SHALL NOT include Luhn checksum |
| | | concatenating the 24-bit OUI with a 24-bit | | | | or SVN information. [ThreeGPP.IMEI] |
| | | identifier assigned by the organisation that | +------+------+-----------------------------------------------------+
| | | purchased the OUI. |
| 0x05 | EUI-60 | This is a 60-bit identifier formed by |
| | | concatenating the 24-bit OUI with a 36-bit |
| | | identifier assigned by the organisation that |
| | | purchased the OUI. |
| 0x06 | EUI-64 | This is a 64-bit identifier formed by |
| | | concatenating the 24-bit OUI with a 40-bit |
| | | identifier assigned by the organisation that |
| | | purchased the OUI. |
+------+--------+---------------------------------------------------+
Table 1: UEID Composition Types Table 1: UEID Composition Types
UEID's are not designed for direct use by humans (e.g., printing on UEID's are not designed for direct use by humans (e.g., printing on
the case of a device), so no textual representation is defined. the case of a device), so no textual representation is defined.
The consumer (the relying party) of a UEID MUST treat a UEID as a The consumer (the relying party) of a UEID MUST treat a UEID as a
completely opaque string of bytes and not make any use of its completely opaque string of bytes and not make any use of its
internal structure. For example, they should not use the OUI part of internal structure. For example, they should not use the OUI part of
a type 0x02 UEID to identify the manufacturer of the device. Instead a type 0x02 UEID to identify the manufacturer of the device. Instead
they should use the OUI claim that is defined elsewhere. The reasons they should use the oemid claim that is defined elsewhere. The
for this are: reasons for this are:
o UEIDs types may vary freely from one manufacturer to the next. o UEIDs types may vary freely from one manufacturer to the next.
o New types of UEIDs may be created. For example, a type 0x07 UEID o New types of UEIDs may be created. For example, a type 0x07 UEID
may be created based on some other manufacturer registration may be created based on some other manufacturer registration
scheme. scheme.
o Device manufacturers are allowed to change from one type of UEID o Device manufacturers are allowed to change from one type of UEID
to another anytime they want. For example, they may find they can to another anytime they want. For example, they may find they can
optimize their manufacturing by switching from type 0x01 to type optimize their manufacturing by switching from type 0x01 to type
0x02 or vice versa. The main requirement on the manufacturer is 0x02 or vice versa. The main requirement on the manufacturer is
that UEIDs be universally unique. that UEIDs be universally unique.
3.4.1. CDDL 3.4.1. ueid CDDL
ueid_claim = ( ueid-claim = (
ueid: bstr ) ueid => bstr .size (7..33)
)
3.5. Origination Claim (origination) 3.5. Origination Claim (origination)
This claim describes the parts of the device or entity that are This claim describes the parts of the device or entity that are
creating the EAT. Often it will be tied back to the device or chip creating the EAT. Often it will be tied back to the device or chip
manufacturer. The following table gives some examples: manufacturer. The following table gives some examples:
+-------------------+-----------------------------------------------+ +-------------------+-----------------------------------------------+
| Name | Description | | Name | Description |
+-------------------+-----------------------------------------------+ +-------------------+-----------------------------------------------+
skipping to change at page 12, line 5 skipping to change at page 12, line 42
| Acme-TA | The EATs are generated in a Trusted | | Acme-TA | The EATs are generated in a Trusted |
| | Application (TA) authored by "Acme" | | | Application (TA) authored by "Acme" |
+-------------------+-----------------------------------------------+ +-------------------+-----------------------------------------------+
TODO: consider a more structure approach where the name and the URI TODO: consider a more structure approach where the name and the URI
and other are in separate fields. and other are in separate fields.
TODO: This needs refinement. It is somewhat parallel to issuer claim TODO: This needs refinement. It is somewhat parallel to issuer claim
in CWT in that it describes the authority that created the token. in CWT in that it describes the authority that created the token.
3.5.1. CDDL 3.5.1. origination CDDL
origination_claim = ( origination-claim = (
origination: string_or_uri ) origination => string-or-uri
)
3.6. OEM Identification by IEEE (oemid) 3.6. OEM Identification by IEEE (oemid)
The IEEE operates a global registry for MAC addresses and company The IEEE operates a global registry for MAC addresses and company
IDs. This claim uses that database to identify OEMs. The contents IDs. This claim uses that database to identify OEMs. The contents
of the claim may be either an IEEE MA-L, MA-M, MA-S or an IEEE CID of the claim may be either an IEEE MA-L, MA-M, MA-S or an IEEE CID
[IEEE.RA]. An MA-L, formerly known as an OUI, is a 24-bit value used [IEEE.RA]. An MA-L, formerly known as an OUI, is a 24-bit value used
as the first half of a MAC address. MA-M similarly is a 28-bit value as the first half of a MAC address. MA-M similarly is a 28-bit value
uses as the first part of a MAC address, and MA-S, formerly known as uses as the first part of a MAC address, and MA-S, formerly known as
OUI-36, a 36-bit value. Many companies already have purchased one of OUI-36, a 36-bit value. Many companies already have purchased one of
these. A CID is also a 24-bit value from the same space as an MA-L, these. A CID is also a 24-bit value from the same space as an MA-L,
but not for use as a MAC address. IEEE has published Guidelines for but not for use as a MAC address. IEEE has published Guidelines for
Use of EUI, OUI, and CID [OUI.Guide] and provides a lookup services Use of EUI, OUI, and CID [OUI.Guide] and provides a lookup services
[OUI.Lookup] [OUI.Lookup]
Companies that have more than one of these IDs or MAC address blocks Companies that have more than one of these IDs or MAC address blocks
skipping to change at page 12, line 29 skipping to change at page 13, line 19
these. A CID is also a 24-bit value from the same space as an MA-L, these. A CID is also a 24-bit value from the same space as an MA-L,
but not for use as a MAC address. IEEE has published Guidelines for but not for use as a MAC address. IEEE has published Guidelines for
Use of EUI, OUI, and CID [OUI.Guide] and provides a lookup services Use of EUI, OUI, and CID [OUI.Guide] and provides a lookup services
[OUI.Lookup] [OUI.Lookup]
Companies that have more than one of these IDs or MAC address blocks Companies that have more than one of these IDs or MAC address blocks
should pick one and prefer that for all their devices. should pick one and prefer that for all their devices.
Commonly, these are expressed in Hexadecimal Representation Commonly, these are expressed in Hexadecimal Representation
[IEEE.802-2001] also called the Canonical format. When this claim is [IEEE.802-2001] also called the Canonical format. When this claim is
encoded order of bytes in the bstr are the same as the order in the encoded the order of bytes in the bstr are the same as the order in
Hexadecimal Representation. For example, an MA-L like "AC-DE-48" the Hexadecimal Representation. For example, an MA-L like "AC-DE-48"
would be encoded in 3 bytes with values 0xAC, 0xDE, 0x48. For JSON would be encoded in 3 bytes with values 0xAC, 0xDE, 0x48. For JSON
encoded tokens, this is further base64url encoded. encoded tokens, this is further base64url encoded.
3.6.1. CDDL 3.6.1. oemid CDDL
oemid_claim = ( oemid-claim = (
oemid: bstr ) oemid => bstr
)
3.7. The Security Level Claim (security_level) 3.7. The Security Level Claim (security-level)
EATs have a claim that roughly characterizes the device / entities EATs have a claim that roughly characterizes the device / entities
ability to defend against attacks aimed at capturing the signing key, ability to defend against attacks aimed at capturing the signing key,
forging claims and at forging EATs. This is done by roughly defining forging claims and at forging EATs. This is done by roughly defining
four security levels as described below. This is similar to the four security levels as described below. This is similar to the
security levels defined in the Metadata Service defined by the Fast security levels defined in the Metadata Service defined by the Fast
Identity Online (FIDO) Alliance (TODO: reference). Identity Online (FIDO) Alliance (TODO: reference).
These claims describe security environment and countermeasures These claims describe security environment and countermeasures
available on the end-entity / client device where the attestation key available on the end-entity / client device where the attestation key
skipping to change at page 13, line 33 skipping to change at page 14, line 22
4 - Hardware Entities at this level must include substantial defense 4 - Hardware Entities at this level must include substantial defense
against physical or electrical attacks against the device itself. against physical or electrical attacks against the device itself.
It is assumed any potential attacker has captured the device and It is assumed any potential attacker has captured the device and
can disassemble it. Example include TPMs and Secure Elements. can disassemble it. Example include TPMs and Secure Elements.
This claim is not intended as a replacement for a proper end-device This claim is not intended as a replacement for a proper end-device
security certification schemes such as those based on FIPS (TODO: security certification schemes such as those based on FIPS (TODO:
reference) or those based on Common Criteria (TODO: reference). The reference) or those based on Common Criteria (TODO: reference). The
claim made here is solely a self-claim made by the Entity Originator. claim made here is solely a self-claim made by the Entity Originator.
3.7.1. CDDL 3.7.1. security-level CDDL
security_level_type = ( security-level-type = &(
unrestricted: 1, unrestricted: 1,
restricted: 2, restricted: 2,
secure_restricted: 3, secure-restricted: 3,
hardware: 4 hardware: 4
) )
security_level_claim = ( security-level-claim = (
security_level: security_level_type ) security-level => security-level-type
)
3.8. Secure Boot and Debug Enable State Claims (boot_state) 3.8. Secure Boot and Debug Enable State Claims (boot-state)
This claim is an array of five Boolean values indicating the boot and This claim is an array of five Boolean values indicating the boot and
debug state of the entity. debug state of the entity.
3.8.1. Secure Boot Enabled 3.8.1. Secure Boot Enabled
This indicates whether secure boot is enabled either for an entire This indicates whether secure boot is enabled either for an entire
device or an individual submodule. If it appears at the device device or an individual submodule. If it appears at the device
level, then this means that secure boot is enabled for all level, then this means that secure boot is enabled for all
submodules. Secure boot enablement allows a secure boot loader to submodules. Secure boot enablement allows a secure boot loader to
skipping to change at page 14, line 40 skipping to change at page 15, line 31
but the end user is not. but the end user is not.
3.8.5. Debug Full Permanent Disable 3.8.5. Debug Full Permanent Disable
This claim indicates whether debug capabilities for the entity are This claim indicates whether debug capabilities for the entity are
permanently disabled (i.e. value of 'true'). This value can only be permanently disabled (i.e. value of 'true'). This value can only be
set to 'true' if no party can enable debug capabilities for the set to 'true' if no party can enable debug capabilities for the
entity. Often this is implemented by blowing a fuse on a chip as entity. Often this is implemented by blowing a fuse on a chip as
fuses cannot be restored once blown. fuses cannot be restored once blown.
3.8.6. CDDL 3.8.6. boot-state CDDL
boot_state_type = [ boot-state-type = [
secure_boot_enabled=> bool, secure-boot-enabled => bool,
debug_disabled=> bool, debug-disabled => bool,
debug_disabled_since_boot=> bool, debug-disabled-since-boot => bool,
debug_permanent_disable=> bool, debug-permanent-disable => bool,
debug_full_permanent_disable=> bool debug-full-permanent-disable => bool
] ]
boot_state_claim = ( boot-state-claim = (
boot_state: boot_state_type boot-state => boot-state-type
) )
3.9. The Location Claim (location) 3.9. The Location Claim (location)
The location claim is a CBOR-formatted object that describes the The location claim is a CBOR-formatted object that describes the
location of the device entity from which the attestation originates. location of the device entity from which the attestation originates.
It is comprised of a map of additional sub claims that represent the It is comprised of a map of additional sub claims that represent the
actual location coordinates (latitude, longitude and altitude). The actual location coordinates (latitude, longitude and altitude). The
location coordinate claims are consistent with the WGS84 coordinate location coordinate claims are consistent with the WGS84 coordinate
system [WGS84]. In addition, a sub claim providing the estimated system [WGS84]. In addition, a sub claim providing the estimated
accuracy of the location measurement is defined. accuracy of the location measurement is defined.
3.9.1. CDDL 3.9.1. location CDDL
location_type = { location-type = {
latitude => number, latitude => number,
longitude => number, longitude => number,
altitude => number, ? altitude => number,
accuracy => number, ? accuracy => number,
altitude_accuracy => number, ? altitude-accuracy => number,
heading => number, ? heading => number,
speed => number ? speed => number
} }
location_claim = ( location-claim = (
location: location_type ) location => location-type
)
3.10. The Age Claim (age) 3.10. The Age Claim (age)
The "age" claim contains a value that represents the number of The "age" claim contains a value that represents the number of
seconds that have elapsed since the token was created, measurement seconds that have elapsed since the token was created, measurement
was made, or location was obtained. Typical attestable values are was made, or location was obtained. Typical attestable values are
sent as soon as they are obtained. However, in the case that such a sent as soon as they are obtained. However, in the case that such a
value is buffered and sent at a later time and a sufficiently value is buffered and sent at a later time and a sufficiently
accurate time reference is unavailable for creation of a timestamp, accurate time reference is unavailable for creation of a timestamp,
then the age claim is provided. then the age claim is provided.
age_claim = ( 3.10.1. age CDDL
age: uint)
age-claim = (
age => uint
)
3.11. The Uptime Claim (uptime) 3.11. The Uptime Claim (uptime)
The "uptime" claim contains a value that represents the number of The "uptime" claim contains a value that represents the number of
seconds that have elapsed since the entity or submod was last booted. seconds that have elapsed since the entity or submod was last booted.
3.11.1. CDDL 3.11.1. uptime CDDL
uptime_claim = (
uptime: uint )
3.12. Nested EATs, the EAT Claim (nested_eat)
It is allowed for one EAT to be embedded in another. This is for
complex devices that have more than one subsystem capable of
generating an EAT. For example, one might be the device-wide EAT
that is low to medium security and another from a Secure Element or
similar that is high security.
The contents of the "nested_eat" claim must be a fully signed,
optionally encrypted, EAT token.
3.12.1. CDDL
nested_eat_claim = (
nested_eat: nested_eat_type)
A nested_eat_type is defined in words rather than CDDL. It is either uptime-claim = (
a full CWT or JWT including the COSE or JOSE signing. uptime => uint
)
3.13. The Submods Claim (submods) 3.12. The Submods Part of a Token (submods)
Some devices are complex, having many subsystems or submodules. A Some devices are complex, having many subsystems or submodules. A
mobile phone is a good example. It may have several connectivity mobile phone is a good example. It may have several connectivity
submodules for communications (e.g., Wi-Fi and cellular). It may submodules for communications (e.g., Wi-Fi and cellular). It may
have subsystems for low-power audio and video playback. It may have have subsystems for low-power audio and video playback. It may have
one or more security-oriented subsystems like a TEE or a Secure one or more security-oriented subsystems like a TEE or a Secure
Element. Element.
The claims for each these can be grouped together in a submodule. The claims for each these can be grouped together in a submodule.
Specifically, the "submods" claim is an array. Each item in the The submods part of a token a single map/object with many entries,
array is a CBOR map containing all the claims for a particular one per submodule. There is only one submods map in a token. It is
submodule. identified by its specific label. It is a peer to other claims, but
it is not called a claim because it is a container for a claim set
rather than an individual claim. This submods part of a token allows
what might be called recursion. It allows claim sets inside of claim
sets inside of claims sets...
The security level of the submod is assumed to be at the same level 3.12.1. Two Types of Submodules
as the main entity unless there is a security level claim in that
submodule indicating otherwise. The security level of a submodule
can never be higher (more secure) than the security level of the EAT
it is a part of.
3.13.1. The submod_name Claim Each entry in the submod map one of two types:
Each submodule should have a submod_name claim that is descriptive o A non-token submodule that is a map or object directly containing
name. This name should be the CBOR txt type. claims for the submodule.
3.13.2. CDDL o A nested EAT that is a fully-formed, independently signed EAT
token
In the following a generic_claim_type is any CBOR map entry or JSON 3.12.1.1. Non-token Submodules
name/value pair.
submod_name_type = ( Essentially this type of submodule, is just a sub-map or sub-object
submod_name: tstr ) containing claims. It is recognized from the other type by being a
data item of type map in CBOR or by being an object in JSON.
submods_type = [ * submod_claims ] The contents are claims about the submodule of types defined in this
document or anywhere else claims types are defined.
submod_claims = { 3.12.1.2. Nested EATs
submod_name_type,
* generic_claim_type
}
submods_claim = ( This type of submodule is a fully formed EAT as described here. In
submods: submod_type ) this case the submodule has key material distinct from the containing
EAT token that allows it to sign on its own.
4. Data Model When an EAT is nested in another EAT as a submodule the nested EAT
MUST use the CBOR CWT tag. This clearly distinguishes it from the
non-token submodules.
This makes use of the types defined in CDDL Appendix D, Standard 3.12.2. No Inheritance
Prelude.
4.1. Common CDDL Types The subordinate modules do not inherit anything from the containing
token. The subordinate modules must explicitly include all of their
claims. This is the case even for claims like the nonce and age.
string_or_uri = #6.32(tstr) / tstr; See JSON section below for JSON encoding of string_or_uri This rule is in place for simplicity. It avoids complex inheritance
rules that might vary from one type of claim to another. (TODO: fix
the boot claim which does have inheritance as currently described).
4.2. CDDL for CWT-defined Claims 3.12.3. Security Levels
This section provides CDDL for the claims defined in CWT. It is non- The security level of the non-token subordinate modules should always
normative as [RFC8392] is the authoritative definition of these be less than or equal to that of the containing modules in the case
claims. of non-token submodules. It makes no sense for a module of lesser
security to be signing claims of a module of higher security. An
example of this is a TEE signing claims made by the non-TEE parts
(e.g. the high-level OS) of the device.
cwt_claim = ( The opposite may be true for the nested tokens. They usually have
issuer_claim // their own more secure key material. An example of this is an
subject_claim // embedded secure element.
audience_claim //
expiration_claim // 3.12.4. Submodule Names
not_before_claim //
issued_at_calim // The label or name for each submodule in the submods map is a text
cwt_id_claim string naming the submodule. No submodules may have the same name.
3.12.5. submods CDDL
submods-type = { + submodule }
submodule = (
submod_name => eat-claims / eat-token
) )
issuer_claim = ( submod_name = tstr / int
issuer: string_or_uri )
subject_claim = ( submods-part = (
subject: string_or_uri ) submods => submod-type
)
audience_claim = ( 4. Encoding
audience: string_or_uri )
expiration_claim = ( This makes use of the types defined in CDDL Appendix D, Standard
expiration: time ) Prelude.
not_before_claim = ( 4.1. Common CDDL Types
not_before: time )
issued_at_calim = ( string-or-uri = uri / tstr; See JSON section below for JSON encoding of string-or-uri
issued_at: time )
cwt_id_claim = ( 4.2. CDDL for CWT-defined Claims
cwt_id: bstr )
This section provides CDDL for the claims defined in CWT. It is non-
normative as [RFC8392] is the authoritative definition of these
claims.
rfc8392-claim //= ( issuer => text )
rfc8392-claim //= ( subject => text )
rfc8392-claim //= ( audience => text )
rfc8392-claim //= ( expiration => time )
rfc8392-claim //= ( not-before => time )
rfc8392-claim //= ( issued-at => time )
rfc8392-claim //= ( cwt-id => bytes )
issuer = 1 issuer = 1
subject = 2 subject = 2
audience = 3 audience = 3
expiration = 4 expiration = 4
not_before = 5 not-before = 5
issued_at = 6 issued-at = 6
cwt_id = 7 cwt-id = 7
cwt-claim = rfc8392-claim
4.3. JSON 4.3. JSON
4.3.1. JSON Labels 4.3.1. JSON Labels
ueid = "ueid" ueid = "ueid"
origination = "origination" origination = "origination"
oemid = "oemid" oemid = "oemid"
security_level = "security_level" security-level = "security-level"
boot_state = "boot_state" boot-state = "boot-state"
location = "location" location = "location"
age = "age" age = "age"
uptime = "uptime" uptime = "uptime"
nested_eat = "nested_eat" nested-eat = "nested-eat"
submods = "submods" submods = "submods"
latitude = "lat"" latitude = "lat"
longitude = "long"" longitude = "long""
altitude = "alt" altitude = "alt"
accuracy = "accry" accuracy = "accry"
altitude_accuracy = "alt_accry" altitude-accuracy = "alt-accry"
heading = "heading" heading = "heading"
speed = "speed" speed = "speed"
4.3.2. JSON Interoperability 4.3.2. JSON Interoperability
JSON should be encoded per RFC 8610 Appendix E. In addition, the JSON should be encoded per RFC 8610 Appendix E. In addition, the
following CDDL types are encoded in JSON as follows: following CDDL types are encoded in JSON as follows:
o bstr - must be base64url encoded o bstr - must be base64url encoded
o time - must be encoded as NumericDate as described section 2 of o time - must be encoded as NumericDate as described section 2 of
[RFC7519]. [RFC7519].
o string_or_uri - must be encoded as StringOrURI as described o string-or-uri - must be encoded as StringOrURI as described
section 2 of [RFC7519]. section 2 of [RFC7519].
4.4. CBOR 4.4. CBOR
4.4.1. Labels 4.4.1. CBOR Labels
ueid = 8 ueid = To_be_assigned
origination = 9 origination = To_be_assigned
oemid = 10 oemid = To_be_assigned
security_level = 11 security-level = To_be_assigned
boot_state = 12 boot-state = To_be_assigned
location = 13 location = To_be_assigned
age = 14 age = To_be_assigned
uptime = 15 uptime = To_be_assigned
nested_eat = 16 submods = To_be_assigned
submods = 17 nonce = To_be_assigned
submod_name = 18
nonce = 19
latitude = 1 latitude = 1
longitude = 2 longitude = 2
altitude = 3 altitude = 3
accuracy = 4 accuracy = 4
altitude_accuracy = 5 altitude-accuracy = 5
heading = 6 heading = 6
speed = 7 speed = 7
4.4.2. CBOR Interoperability 4.4.2. CBOR Interoperability
Variations in the CBOR serializations supported in CBOR encoding and Variations in the CBOR serializations supported in CBOR encoding and
decoding are allowed and suggests that CBOR-based protocols specify decoding are allowed and suggests that CBOR-based protocols specify
how this variation is handled. This section specifies what formats how this variation is handled. This section specifies what formats
MUST be supported in order to achieve interoperability. MUST be supported in order to achieve interoperability.
skipping to change at page 21, line 39 skipping to change at page 22, line 36
o Floating Point - The entity may use any floating-point encoding. o Floating Point - The entity may use any floating-point encoding.
The relying party must support decoding of all types of floating- The relying party must support decoding of all types of floating-
point. point.
o Other types - Use of Other types like bignums, regular expressions o Other types - Use of Other types like bignums, regular expressions
and such, SHOULD NOT be used. The server MAY support them but is and such, SHOULD NOT be used. The server MAY support them but is
not required to so interoperability is not guaranteed. not required to so interoperability is not guaranteed.
4.5. Collected CDDL 4.5. Collected CDDL
A generic_claim is any CBOR map entry or JSON name/value pair. A generic-claim is any CBOR map entry or JSON name/value pair.
eat_claims = { ; the top-level payload that is signed using COSE or JOSE eat-claims = { ; the top-level payload that is signed using COSE or JOSE
* claim * claim
} }
claim = ( claim = (
ueid_claim // ueid-claim //
origination_claim // origination-claim //
oemid_claim // oemid-claim //
security_level_claim // security-level-claim //
boot_state_claim // boot-state-claim //
location_claim // location-claim //
age_claim // age-claim //
uptime_claim // uptime-claim //
nested_eat_claim // submods-part //
cwt_claim // cwt-claim //
generic_claim_type // generic-claim-type //
) )
eat-token ; This is a set of eat-claims signed using COSE
TODO: copy the rest of the CDDL here (wait until the CDDL is more TODO: copy the rest of the CDDL here (wait until the CDDL is more
settled so as to avoid copying multiple times) settled so as to avoid copying multiple times)
5. IANA Considerations 5. IANA Considerations
5.1. Reuse of CBOR Web Token (CWT) Claims Registry 5.1. Reuse of CBOR Web Token (CWT) Claims Registry
Claims defined for EAT are compatible with those of CWT so the CWT Claims defined for EAT are compatible with those of CWT so the CWT
Claims Registry is re used. No new IANA registry is created. All Claims Registry is re used. No new IANA registry is created. All
skipping to change at page 24, line 7 skipping to change at page 25, line 7
UEID. UEID.
Note that some of these privacy preservation strategies result in Note that some of these privacy preservation strategies result in
multiple UEIDs per device. Each UEID is used in a different context, multiple UEIDs per device. Each UEID is used in a different context,
use case or system on the device. However, from the view of the use case or system on the device. However, from the view of the
relying party, there is just one UEID and it is still globally relying party, there is just one UEID and it is still globally
universal across manufacturers. universal across manufacturers.
7. Security Considerations 7. Security Considerations
TODO: Perhaps this can be the same as CWT / COSE, but not sure yet The security considerations provided in Section 8 of [RFC8392] and
because it involves so much entity / device security that those do Section 11 of [RFC7519] apply to EAT in its CWT and JWT form,
not. respectively. In addition, implementors should consider the
following.
7.1. Key Provisioning
Private key material can be used to sign and/or encrypt the EAT, or
can be used to derive the keys used for signing and/or encryption.
In some instances, the manufacturer of the entity may create the key
material separately and provision the key material in the entity
itself. The manfuacturer of any entity that is capable of producing
an EAT should take care to ensure that any private key material be
suitably protected prior to provisioning the key material in the
entity itself. This can require creation of key material in an
enclave (see [RFC4949] for definition of "enclave"), secure
transmission of the key material from the enclave to the entity using
an appropriate protocol, and persistence of the private key material
in some form of secure storage to which (preferably) only the entity
has access.
7.1.1. Transmission of Key Material
Regarding transmission of key material from the enclave to the
entity, the key material may pass through one or more intermediaries.
Therefore some form of protection ("key wrapping") may be necessary.
The transmission itself may be performed electronically, but can also
be done by human courier. In the latter case, there should be
minimal to no exposure of the key material to the human (e.g.
encrypted portable memory). Moreover, the human should transport the
key material directly from the secure enclave where it was created to
a destination secure enclave where it can be provisioned.
7.2. Transport Security
As stated in Section 8 of [RFC8392], "The security of the CWT relies
upon on the protections offered by COSE". Similar considerations
apply to EAT when sent as a CWT. However, EAT introduces the concept
of a nonce to protect against replay. Since an EAT may be created by
an entity that may not support the same type of transport security as
the consumer of the EAT, intermediaries may be required to bridge
communications between the entity and consumer. As a result, it is
RECOMMENDED that both the consumer create a nonce, and the entity
leverage the nonce along with COSE mechanisms for encryption and/or
signing to create the EAT.
Similar considerations apply to the use of EAT as a JWT. Although
the security of a JWT leverages the JSON Web Encryption (JWE) and
JSON Web Signature (JWS) specifications, it is still recommended to
make use of the EAT nonce.
7.3. Multiple EAT Consumers
In many cases, more than one EAT consumer may be required to fully
verify the entity attestation. Examples include individual consumers
for nested EATs, or consumers for individual claims with an EAT.
When multiple consumers are required for verification of an EAT, it
is important to minimize information exposure to each consumer. In
addition, the communication between multiple consumers should be
secure.
For instance, consider the example of an encrypted and signed EAT
with multiple claims. A consumer may receive the EAT (denoted as the
"receiving consumer"), decrypt its payload, verify its signature, but
then pass specific subsets of claims to other consumers for
evaluation ("downstream consumers"). Since any COSE encryption will
be removed by the receiving consumer, the communication of claim
subsets to any downstream consumer should leverage a secure protocol
(e.g.one that uses transport-layer security, i.e. TLS),
However, assume the EAT of the previous example is hierarchical and
each claim subset for a downstream consumer is created in the form of
a nested EAT. Then transport security between the receiving and
downstream consumers is not strictly required. Nevertheless,
downstream consumers of a nested EAT should provide a nonce unique to
the EAT they are consuming.
8. References 8. References
8.1. Normative References 8.1. Normative References
[IANA.CWT.Claims] [IANA.CWT.Claims]
IANA, "CBOR Web Token (CWT) Claims", IANA, "CBOR Web Token (CWT) Claims",
<http://www.iana.org/assignments/cwt>. <http://www.iana.org/assignments/cwt>.
[IANA.JWT.Claims] [IANA.JWT.Claims]
skipping to change at page 25, line 11 skipping to change at page 27, line 36
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, [RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/info/rfc8392>. May 2018, <https://www.rfc-editor.org/info/rfc8392>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>. June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[ThreeGPP.IMEI]
3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Terminals; Numbering,
addressing and identification", 2019,
<https://portal.3gpp.org/desktopmodules/Specifications/
SpecificationDetails.aspx?specificationId=729>.
[TIME_T] The Open Group Base Specifications, "Vol. 1: Base [TIME_T] The Open Group Base Specifications, "Vol. 1: Base
Definitions, Issue 7", Section 4.15 'Seconds Since the Definitions, Issue 7", Section 4.15 'Seconds Since the
Epoch', IEEE Std 1003.1, 2013 Edition, 2013, Epoch', IEEE Std 1003.1, 2013 Edition, 2013,
<http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/
V1_chap04.html#tag_04_15>. V1_chap04.html#tag_04_15>.
[WGS84] National Imagery and Mapping Agency, "National Imagery and [WGS84] National Imagery and Mapping Agency, "National Imagery and
Mapping Agency Technical Report 8350.2, Third Edition", Mapping Agency Technical Report 8350.2, Third Edition",
2000, <http://earth- 2000, <http://earth-
info.nga.mil/GandG/publications/tr8350.2/wgs84fin.pdf>. info.nga.mil/GandG/publications/tr8350.2/wgs84fin.pdf>.
8.2. Informative References 8.2. Informative References
[ASN.1] International Telecommunication Union, "Information [ASN.1] International Telecommunication Union, "Information
Technology -- ASN.1 encoding rules: Specification of Basic Technology -- ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and Encoding Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER)", ITU-T Recommendation Distinguished Encoding Rules (DER)", ITU-T Recommendation
X.690, 1994. X.690, 1994.
[BirthdayAttack]
"Birthday attack",
<https://en.wikipedia.org/wiki/Birthday_attack.>.
[ECMAScript] [ECMAScript]
"Ecma International, "ECMAScript Language Specification, "Ecma International, "ECMAScript Language Specification,
5.1 Edition", ECMA Standard 262", June 2011, 5.1 Edition", ECMA Standard 262", June 2011,
<http://www.ecma-international.org/ecma-262/5.1/ECMA- <http://www.ecma-international.org/ecma-262/5.1/ECMA-
262.pdf>. 262.pdf>.
[IDevID] "IEEE Standard, "IEEE 802.1AR Secure Device Identifier"", [IDevID] "IEEE Standard, "IEEE 802.1AR Secure Device Identifier"",
December 2009, <http://standards.ieee.org/findstds/ December 2009, <http://standards.ieee.org/findstds/
standard/802.1AR-2009.html>. standard/802.1AR-2009.html>.
skipping to change at page 26, line 17 skipping to change at page 28, line 49
Organizationally Unique Identifier (OUI), and Company ID Organizationally Unique Identifier (OUI), and Company ID
(CID)", August 2017, (CID)", August 2017,
<https://standards.ieee.org/content/dam/ieee- <https://standards.ieee.org/content/dam/ieee-
standards/standards/web/documents/tutorials/eui.pdf>. standards/standards/web/documents/tutorials/eui.pdf>.
[OUI.Lookup] [OUI.Lookup]
"IEEE Registration Authority Assignments", "IEEE Registration Authority Assignments",
<https://regauth.standards.ieee.org/standards-ra-web/pub/ <https://regauth.standards.ieee.org/standards-ra-web/pub/
view.html#registries>. view.html#registries>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/info/rfc4122>.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
<https://www.rfc-editor.org/info/rfc4949>.
[Webauthn] [Webauthn]
Worldwide Web Consortium, "Web Authentication: A Web API Worldwide Web Consortium, "Web Authentication: A Web API
for accessing scoped credentials", 2016. for accessing scoped credentials", 2016.
Appendix A. Examples Appendix A. Examples
A.1. Very Simple EAT A.1. Very Simple EAT
This is shown in CBOR diagnostic form. Only the payload signed by This is shown in CBOR diagnostic form. Only the payload signed by
COSE is shown. COSE is shown.
{ {
/ nonce (cti) / 7:h'948f8860d13a463e8e', / nonce / 9:h'948f8860d13a463e8e',
/ UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f', / UEID / 10:h'0198f50a4ff6c05861c8860d13a638ea4fe2f',
/ boot_state / 12:{true, true, true, true, false} / boot-state / 12:{true, true, true, true, false}
/ time stamp (iat) / 6:1526542894, / time stamp (iat) / 6:1526542894,
} }
A.2. Example with Submodules, Nesting and Security Levels A.2. Example with Submodules, Nesting and Security Levels
{ {
/ nonce / 7:h'948f8860d13a463e8e', / nonce / 9:h'948f8860d13a463e8e',
/ UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f', / UEID / 10:h'0198f50a4ff6c05861c8860d13a638ea4fe2f',
/ boot_state / 12:{true, true, true, true, false} / boot-state / 12:{true, true, true, true, false}
/ time stamp (iat) / 6:1526542894, / time stamp (iat) / 6:1526542894,
/ seclevel / 11:3, / secure restricted OS / / seclevel / 11:3, / secure restricted OS /
/ submods / 17: / submods / 17:
[ {
/ 1st submod, an Android Application / { / first submod, an Android Application / "Android App Foo" : {
/ submod_name / 18:'Android App "Foo"', / seclevel / 11:1, / unrestricted /
/ seclevel / 11:1, / unrestricted / / app data / -70000:'text string'
/ app data / -70000:'text string'
}, },
/ 2nd submod, A nested EAT from a secure element / { / 2nd submod, A nested EAT from a secure element / "Secure Element Eat" :
/ submod_name / 18:'Secure Element EAT', / eat / 61( 18(
/ eat / 16:61( 18( / an embedded EAT, bytes of which are not shown /
/ an embedded EAT / [ /...COSE_Sign1 bytes with payload.../ ]
)) ))
/ 3rd submod, information about Linux Android / "Linux Android": {
/ seclevel / 11:1, / unrestricted /
/ custom - release / -80000:'8.0.0',
/ custom - version / -80001:'4.9.51+'
} }
/ 3rd submod, information about Linux Android / { }
/ submod_name/ 18:'Linux Android',
/ seclevel / 11:1, / unrestricted /
/ custom - release / -80000:'8.0.0',
/ custom - version / -80001:'4.9.51+'
}
]
} }
Appendix B. Changes from Previous Drafts
Appendix B. UEID Design Rationale
B.1. Collision Probability
This calculation is to determine the probability of a collision of
UEIDs given the total possible entity population and the number of
entities in a particular entity management database.
Three different sized databases are considered. The number of
devices per person roughly models non-personal devices such as
traffic lights, devices in stores they shop in, facilities they work
in and so on, even considering individual light bulbs. A device may
have individually attested subsystems, for example parts of a car or
a mobile phone. It is assumed that the largest database will have at
most 10% of the world's population of devices. Note that databases
that handle more than a trillion records exist today.
The trillion-record database size models an easy-to-imagine reality
over the next decades. The quadrillion-record database is roughly at
the limit of what is imaginable and should probably be accommodated.
The 100 quadrillion datadbase is highly speculative perhaps involving
nanorobots for every person, livestock animal and domesticated bird.
It is included to round out the analysis.
Note that the items counted here certainly do not have IP address and
are not individually connected to the network. They may be connected
to internal buses, via serial links, Bluetooth and so on. This is
not the same problem as sizing IP addresses.
+---------+------------+--------------+------------+----------------+
| People | Devices / | Subsystems / | Database | Database Size |
| | Person | Device | Portion | |
+---------+------------+--------------+------------+----------------+
| 10 | 100 | 10 | 10% | trillion |
| billion | | | | (10^12) |
| 10 | 100,000 | 10 | 10% | quadrillion |
| billion | | | | (10^15) |
| 100 | 1,000,000 | 10 | 10% | 100 |
| billion | | | | quadrillion |
| | | | | (10^17) |
+---------+------------+--------------+------------+----------------+
This is conceptually similar to the Birthday Problem where m is the
number of possible birthdays, always 365, and k is the number of
people. It is also conceptually similar to the Birthday Attack where
collisions of the output of hash functions are considered.
The proper formula for the collision calculation is
p = 1 - e^{-k^2/(2n)}
p Collision Probability
n Total possible population
k Actual population
However, for the very large values involved here, this formula
requires floating point precision higher than commonly available in
calculators and SW so this simple approximation is used. See
[BirthdayAttack].
p = k^2 / 2n
For this calculation:
p Collision Probability
n Total population based on number of bits in UEID
k Population in a database
+----------------------+--------------+--------------+--------------+
| Database Size | 128-bit UEID | 192-bit UEID | 256-bit UEID |
+----------------------+--------------+--------------+--------------+
| trillion (10^12) | 2 * 10^-15 | 8 * 10^-35 | 5 * 10^-55 |
| quadrillion (10^15) | 2 * 10^-09 | 8 * 10^-29 | 5 * 10^-49 |
| 100 quadrillion | 2 * 10^-05 | 8 * 10^-25 | 5 * 10^-45 |
| (10^17) | | | |
+----------------------+--------------+--------------+--------------+
Next, to calculate the probability of a collision occurring in one
year's operation of a database, it is assumed that the database size
is in a steady state and that 10% of the database changes per year.
For example, a trillion record database would have 100 billion states
per year. Each of those states has the above calculated probability
of a collision.
This assumption is a worst-case since it assumes that each state of
the database is completely independent from the previous state. In
reality this is unlikely as state changes will be the addition or
deletion of a few records.
The following tables gives the time interval until there is a
probability of a collision based on there being one tenth the number
of states per year as the number of records in the database.
t = 1 / ((k / 10) * p)
t Time until a collision
p Collision probability for UEID size
k Database size
+---------------------+---------------+--------------+--------------+
| Database Size | 128-bit UEID | 192-bit UEID | 256-bit UEID |
+---------------------+---------------+--------------+--------------+
| trillion (10^12) | 60,000 years | 10^24 years | 10^44 years |
| quadrillion (10^15) | 8 seconds | 10^14 years | 10^34 years |
| 100 quadrillion | 8 | 10^11 years | 10^31 years |
| (10^17) | microseconds | | |
+---------------------+---------------+--------------+--------------+
Clearly, 128 bits is enough for the near future thus the requirement
that UEIDs be a minimum of 128 bits.
There is no requirement for 256 bits today as quadrillion-record
databases are not expected in the near future and because this time-
to-collision calculation is a very worst case. A future update of
the standard may increase the requirement to 256 bits, so there is a
requirement that implementations be able to receive 256-bit UEIDs.
B.2. No Use of UUID
A UEID is not a UUID [RFC4122] by conscious choice for the following
reasons.
UUIDs are limited to 128 bits which may not be enough for some future
use cases.
Today, cryptographic-quality random numbers are available from common
CPUs and hardware. This hardware was introduced between 2010 and
2015. Operating systems and cryptographic libraries give access to
this hardware. Consequently, there is little need for
implementations to construct such random values from multiple sources
on their own.
Version 4 UUIDs do allow for use of such cryptographic-quality random
numbers, but do so by mapping into the overall UUID structure of time
and clock values. This structure is of no value here yet adds
complexity. It also slightly reduces the number of actual bits with
entropy.
UUIDs seem to have been designed for scenarios where the implementor
does not have full control over the environment and uniqueness has to
be constructed from identifiers at hand. UEID takes the view that
hardware, software and/or manufacturing process directly implement
UEID in a simple and direct way. It takes the view that
cryptographic quality random number generators are readily available
as they are implemented in commonly used CPU hardware.
Appendix C. Changes from Previous Drafts
The following is a list of known changes from the previous drafts. The following is a list of known changes from the previous drafts.
This list is non-authoritative. It is meant to help reviewers see This list is non-authoritative. It is meant to help reviewers see
the significant differences. the significant differences.
B.1. From draft-mandyam-rats-eat-00 C.1. From draft-rats-eat-01
o Added UEID design rationale appendix
C.2. From draft-mandyam-rats-eat-00
This is a fairly large change in the orientation of the document, but This is a fairly large change in the orientation of the document, but
not new claims have been added. not new claims have been added.
o Separate information and data model using CDDL. o Separate information and data model using CDDL.
o Say an EAT is a CWT or JWT o Say an EAT is a CWT or JWT
o Use a map to structure the boot_state and location claims o Use a map to structure the boot_state and location claims
B.2. From draft-ietf-rats-eat-01 C.3. From draft-ietf-rats-eat-01
o Clarifications and corrections for OEMID claim o Clarifications and corrections for OEMID claim
o Minor spelling and other fixes o Minor spelling and other fixes
o Add the nonce claim, clarify jti claim o Add the nonce claim, clarify jti claim
C.4. From draft-ietf-rats-eat-02
o Roll all EUIs back into one UEID type
o UEIDs can be one of three lengths, 128, 192 and 256.
o Added appendix justifying UEID design and size.
o Submods part now includes nested eat tokens so they can be named
and there can be more tha one of them
o Lots of fixes to the CDDL
o Added security considerations
Authors' Addresses Authors' Addresses
Giridhar Mandyam Giridhar Mandyam
Qualcomm Technologies Inc. Qualcomm Technologies Inc.
5775 Morehouse Drive 5775 Morehouse Drive
San Diego, California San Diego, California
USA USA
Phone: +1 858 651 7200 Phone: +1 858 651 7200
EMail: mandyam@qti.qualcomm.com EMail: mandyam@qti.qualcomm.com
 End of changes. 92 change blocks. 
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