< draft-ietf-rats-eat-00.txt   draft-ietf-rats-eat-01.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: December 24, 2019 Security Theory LLC Expires: January 5, 2020 Security Theory LLC
M. Ballesteros M. Ballesteros
J. O'Donoghue J. O'Donoghue
Qualcomm Technologies Inc. Qualcomm Technologies Inc.
June 22, 2019 July 04, 2019
The Entity Attestation Token (EAT) The Entity Attestation Token (EAT)
draft-ietf-rats-eat-00 draft-ietf-rats-eat-01
Abstract Abstract
An attestation format based on concise binary object representation An Entity Attestation Token (EAT) provides a signed (attested) set of
(CBOR) is proposed that is suitable for inclusion in a CBOR Web Token claims that describe state and characteristics of an entity,
(CWT), know as the Entity Attestation Token (EAT). The associated typically a device like a phone or an IoT device. These claims are
data can be used by a relying party to assess the security state of a used by a relying party to determine how much it wishes to trust the
remote device or module. entity.
An EAT is either a CWT or JWT with some attestation-oriented claims.
To a large degree, all this document does is extend CWT and JWT.
Contributing Contributing
TBD TBD
Status of This Memo Status of This Memo
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Entity Overview . . . . . . . . . . . . . . . . . . . . . 4 1.1. CDDL, CWT and JWT . . . . . . . . . . . . . . . . . . . . 4
1.2. Use of CBOR and COSE . . . . . . . . . . . . . . . . . . 5 1.2. Entity Overview . . . . . . . . . . . . . . . . . . . . . 4
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 . . . . . . . . . . . . . . . . . . . 6
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. The Claims . . . . . . . . . . . . . . . . . . . . . . . . . 8 3. The Claims Information Model . . . . . . . . . . . . . . . . 8
3.1. Universal Entity ID (UEID) Claim . . . . . . . . . . . . 8 3.1. Nonce Claim (cti and jti) . . . . . . . . . . . . . . . . 8
3.2. Origination (origination) Claims . . . . . . . . . . . . 11 3.2. Timestamp claim (iat) . . . . . . . . . . . . . . . . . . 8
3.3. OEM identification by IEEE OUI . . . . . . . . . . . . . 11 3.3. Universal Entity ID Claim (ueid) . . . . . . . . . . . . 8
3.4. Security Level (seclevel) Claim . . . . . . . . . . . . . 12 3.4. Origination Claim (origination) . . . . . . . . . . . . . 11
3.5. Nonce (nonce) Claim . . . . . . . . . . . . . . . . . . . 13 3.4.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 12
3.6. Secure Boot and Debug Enable State Claims . . . . . . . . 13 3.5. OEM identification by IEEE OUI (oemid) . . . . . . . . . 12
3.6.1. Secure Boot Enabled (secbootenabled) Claim . . . . . 13 3.5.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 12
3.6.2. Debug Disabled (debugdisabled) Claim . . . . . . . . 13 3.6. The Security Level Claim (security_level) . . . . . . . . 12
3.6.3. Debug Disabled Since Boot (debugdisabledsincebboot) 3.6.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 13
Claim . . . . . . . . . . . . . . . . . . . . . . . . 13 3.7. Secure Boot and Debug Enable State Claims (boot_state) . 13
3.6.4. Debug Permanent Disable (debugpermanentdisable) Claim 13 3.7.1. Secure Boot Enabled . . . . . . . . . . . . . . . . . 13
3.6.5. Debug Full Permanent Disable 3.7.2. Debug Disabled . . . . . . . . . . . . . . . . . . . 13
(debugfullpermanentdisable) Claim . . . . . . . . . . 14 3.7.3. Debug Disabled Since Boot . . . . . . . . . . . . . . 14
3.7. Location (loc) Claim . . . . . . . . . . . . . . . . . . 14 3.7.4. Debug Permanent Disable . . . . . . . . . . . . . . . 14
3.7.1. lat (latitude) claim . . . . . . . . . . . . . . . . 14 3.7.5. Debug Full Permanent Disable . . . . . . . . . . . . 14
3.7.2. long (longitude) claim . . . . . . . . . . . . . . . 14 3.7.6. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 14
3.7.3. alt (altitude) claim . . . . . . . . . . . . . . . . 14 3.8. The Location Claim (location) . . . . . . . . . . . . . . 14
3.7.4. acc (accuracy) claim . . . . . . . . . . . . . . . . 14 3.8.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 15
3.7.5. altacc (altitude accuracy) claim . . . . . . . . . . 15 3.9. The Age Claim (age) . . . . . . . . . . . . . . . . . . . 15
3.7.6. heading claim . . . . . . . . . . . . . . . . . . . . 15 3.10. The Uptime Claim (uptime) . . . . . . . . . . . . . . . . 15
3.7.7. speed claim . . . . . . . . . . . . . . . . . . . . . 15 3.10.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 15
3.8. ts (timestamp) claim . . . . . . . . . . . . . . . . . . 15 3.11. Nested EATs, the EAT Claim (nested_eat) . . . . . . . . . 15
3.9. age claim . . . . . . . . . . . . . . . . . . . . . . . . 15 3.11.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 16
3.10. uptime claim . . . . . . . . . . . . . . . . . . . . . . 15 3.12. The Submods Claim (submods) . . . . . . . . . . . . . . . 16
3.11. The submods Claim . . . . . . . . . . . . . . . . . . . . 16 3.12.1. The submod_name Claim . . . . . . . . . . . . . . . 16
3.11.1. The submod_name Claim . . . . . . . . . . . . . . . 16 3.12.2. CDDL . . . . . . . . . . . . . . . . . . . . . . . . 16
3.11.2. Nested EATs, the eat Claim . . . . . . . . . . . . . 16 4. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1. Common CDDL Types . . . . . . . . . . . . . . . . . . . . 17
4. CBOR Interoperability . . . . . . . . . . . . . . . . . . . . 16 4.2. CDDL for CWT-defined Claims . . . . . . . . . . . . . . . 17
4.1. Integer Encoding (major type 0 and 1) . . . . . . . . . . 17 4.3. JSON . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2. String Encoding (major type 2 and 3) . . . . . . . . . . 17 4.3.1. JSON Labels . . . . . . . . . . . . . . . . . . . . . 18
4.3. Map and Array Encoding (major type 4 and 5) . . . . . . . 17 4.3.2. JSON Interoperability . . . . . . . . . . . . . . . . 19
4.4. Date and Time . . . . . . . . . . . . . . . . . . . . . . 17 4.4. CBOR . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.5. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.4.1. Labels . . . . . . . . . . . . . . . . . . . . . . . 19
4.6. Floating Point . . . . . . . . . . . . . . . . . . . . . 17 4.4.2. CBOR Interoperability . . . . . . . . . . . . . . . . 20
4.7. Other types . . . . . . . . . . . . . . . . . . . . . . . 17 4.5. Collected CDDL . . . . . . . . . . . . . . . . . . . . . 21
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
5.1. Reuse of CBOR Web Token (CWT) Claims Registry . . . . . . 18 5.1. Reuse of CBOR Web Token (CWT) Claims Registry . . . . . . 21
5.1.1. Claims Registered by This Document . . . . . . . . . 18 5.1.1. Claims Registered by This Document . . . . . . . . . 22
5.2. EAT CBOR Tag Registration . . . . . . . . . . . . . . . . 18 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 22
5.2.1. Tag Registered by This Document . . . . . . . . . . . 18 6.1. UEID Privacy Considerations . . . . . . . . . . . . . . . 22
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19 7. Security Considerations . . . . . . . . . . . . . . . . . . . 23
6.1. UEID Privacy Considerations . . . . . . . . . . . . . . . 19 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
7. Security Considerations . . . . . . . . . . . . . . . . . . . 20 8.1. Normative References . . . . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.2. Informative References . . . . . . . . . . . . . . . . . 24
8.1. Normative References . . . . . . . . . . . . . . . . . . 20 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 26
8.2. Informative References . . . . . . . . . . . . . . . . . 21 A.1. Very Simple EAT . . . . . . . . . . . . . . . . . . . . . 26
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 22 A.2. Example with Submodules, Nesting and Security Levels . . 26
A.1. Very Simple EAT . . . . . . . . . . . . . . . . . . . . . 22 Appendix B. Changes from Previous Drafts . . . . . . . . . . . . 27
A.2. Example with Submodules, Nesting and Security Levels . . 22 B.1. From draft-mandyam-rats-eat-00 . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction 1. Introduction
Remote device attestation is fundamental service that allows a remote Remote device attestation is a fundamental service that allows a
device such as a mobile phone, an Internet-of-Things (IoT) device, or remote device such as a mobile phone, an Internet-of-Things (IoT)
other endpoint to prove itself to a relying party, a server or a device, or other endpoint to prove itself to a relying party, a
service. This allows the relying party to know some characteristics server or a service. This allows the relying party to know some
about the device and decide whether it trusts the device. characteristics about the device and decide whether it trusts the
device.
Remote attestation is a fundamental service that can underlie other Remote attestation is a fundamental service that can underlie other
protocols and services that need to know about the trustworthiness of protocols and services that need to know about the trustworthiness of
the device before proceeding. One good example is biometric the device before proceeding. One good example is biometric
authentication where the biometric matching is done on the device. authentication where the biometric matching is done on the device.
The relying party needs to know that the device is one that is known The relying party needs to know that the device is one that is known
to do biometric matching correctly. Another example is content to do biometric matching correctly. Another example is content
protection where the relying party wants to know the device will protection where the relying party wants to know the device will
protect the data. This generalizes on to corporate enterprises that protect the data. This generalizes on to corporate enterprises that
might want to know that a device is trustworthy before allowing might want to know that a device is trustworthy before allowing
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to do biometric matching correctly. Another example is content to do biometric matching correctly. Another example is content
protection where the relying party wants to know the device will protection where the relying party wants to know the device will
protect the data. This generalizes on to corporate enterprises that protect the data. This generalizes on to corporate enterprises that
might want to know that a device is trustworthy before allowing might want to know that a device is trustworthy before allowing
corporate data to be accessed by it. corporate data to be accessed by it.
The notion of attestation here is large and may include, but is not The notion of attestation here is large and may include, but is not
limited to the following: limited to the following:
o Proof of the make and model of the device hardware (HW) o Proof of the make and model of the device hardware (HW)
o Proof of the make and model of the device processor, particularly o Proof of the make and model of the device processor, particularly
for security oriented chips for security-oriented chips
o Measurement of the software (SW) running on the device o Measurement of the software (SW) running on the device
o Configuration and state of the device o Configuration and state of the device
o Environmental characteristics of the device such as its GPS o Environmental characteristics of the device such as its GPS
location location
The required data format should be general purpose and extensible so 1.1. CDDL, CWT and JWT
that it can work across many use cases. This is why CBOR (see
[RFC7049]) was chosen as the format -- it already supports a rich set
of data types, and is both expressive and extensible. It translates
well to JSON for good interoperation with web technology. It is
compact and can work on very small IoT device. The format proposed
here is small enough that a limited version can be implemented in
pure hardware gates with no software at all. Moreover, the
attestation data is defined in the form of claims that is the same as
CBOR Web Token (CWT, see [RFC8392]). This is the motivation for
defining the Entity Attestation Token, i.e. EAT.
1.1. Entity Overview An EAT token is either a CWT as defined in [RFC8392] or a JWT as
defined in [RFC7519]. This specification defines additional claims
for entity attestation.
This specification uses CDDL, [RFC8610], as the primary formalism to
define each claim. The implementor then interprets the CDDL to come
to either the CBOR [RFC7049] or JSON [ECMAScript] representation. In
the case of JSON, Appendix E of [RFC8610] is followed. Additional
rules are given in Section 4.3.2 of this document where Appendix E is
insufficient. (Note that this is not to define a general means to
translate between CBOR and JSON, but only to define enough such that
the claims defined in this document can be rendered unambiguously in
JSON).
1.2. Entity Overview
An "entity" can be any device or device subassembly ("submodule") An "entity" can be any device or device subassembly ("submodule")
that can generate its own attestation in the form of an EAT. The that can generate its own attestation in the form of an EAT. The
attestation should be cryptographically verifiable by the EAT attestation should be cryptographically verifiable by the EAT
consumer. An EAT at the device-level can be composed of several consumer. An EAT at the device-level can be composed of several
submodule EAT's. It is assumed that any entity that can create an submodule EAT's. It is assumed that any entity that can create an
EAT does so by means of a dedicated root-of-trust (RoT). EAT does so by means of a dedicated root-of-trust (RoT).
Modern devices such as a mobile phone have many different execution Modern devices such as a mobile phone have many different execution
environments operating with different security levels. For example environments operating with different security levels. For example,
it is common for a mobile phone to have an "apps" environment that it is common for a mobile phone to have an "apps" environment that
runs an operating system (OS) that hosts a plethora of downloadable runs an operating system (OS) that hosts a plethora of downloadable
apps. It may also have a TEE (Trusted Execution Environment) that is apps. It may also have a TEE (Trusted Execution Environment) that is
distinct, isolated, and hosts security-oriented functionality like distinct, isolated, and hosts security-oriented functionality like
biometric authentication. Additionally it may have an eSE (embedded biometric authentication. Additionally, it may have an eSE (embedded
Secure Element) - a high security chip with defenses against HW Secure Element) - a high security chip with defenses against HW
attacks that can serve as a RoT. This device attestation format attacks that can serve as a RoT. This device attestation format
allows the attested data to be tagged at a security level from which allows the attested data to be tagged at a security level from which
it originates. In general, any discrete execution environment that it originates. In general, any discrete execution environment that
has an identifiable security level can be considered an entity. has an identifiable security level can be considered an entity.
1.2. Use of CBOR and COSE
Fundamentally this attestation format is a verifiable data format.
It is a collection of data items that can be signed by an attestation
key, hashed, and/or encrypted. As per Section 7 of [RFC8392], the
verification method is in the CWT using the CBOR Object Signing and
Encryption (COSE) methodology (see [RFC8152]).
In addition, the reported attestation data could be determined within
the secure operating environment or written to it from an external
and presumably less trusted entity on the device. In either case,
the source of the reported data must be identifiable by the relying
party.
This attestation format is a single relatively simple signed message.
It is designed to be incorporated into many other protocols and many
other transports. It is also designed such that other SW and apps
can add their own data to the message such that it is also attested.
1.3. EAT Operating Models 1.3. EAT Operating Models
At least the following three participants exist in all EAT operating At least the following three participants exist in all EAT operating
models. Some operating models have additional participants. models. Some operating models have additional participants.
The Entity. This is the phone, the IoT device, the sensor, the sub- The Entity. This is the phone, the IoT device, the sensor, the sub-
assembly or such that the attestation provides information about. assembly or such that the attestation provides information about.
The Manufacturer. The company that made the entity. This may be a The Manufacturer. The company that made the entity. This may be a
chip vendor, a circuit board module vendor or a vendor of finished chip vendor, a circuit board module vendor or a vendor of finished
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o The EAT is transmitted to the relying party. The relying party o The EAT is transmitted to the relying party. The relying party
transmits the EAT to a verification service offered by the transmits the EAT to a verification service offered by the
manufacturer. The server returns the validated claims. manufacturer. The server returns the validated claims.
o The EAT is transmitted directly to a verification service, perhaps o The EAT is transmitted directly to a verification service, perhaps
operated by the manufacturer or perhaps by another party. It operated by the manufacturer or perhaps by another party. It
verifies the EAT and makes the validated claims available to the verifies the EAT and makes the validated claims available to the
relying party. It may even modify the claims in some way and re- relying party. It may even modify the claims in some way and re-
sign the EAT (with a different signing key). sign the EAT (with a different signing key).
This standard supports all these operating models and does not prefer All these operating models are supported and there is no preference
one over the other. It is important to support this variety of of one over the other. It is important to support this variety of
operating models to generally facilitate deployment and to allow for operating models to generally facilitate deployment and to allow for
some special scenarios. One special scenario has a validation some special scenarios. One special scenario has a validation
service that is monetized, most likely by the manufacturer. In service that is monetized, most likely by the manufacturer. In
another, a privacy proxy service processes the EAT before it is another, a privacy proxy service processes the EAT before it is
transmitted to the relying party. In yet another, symmetric key transmitted to the relying party. In yet another, symmetric key
material is used for signing. In this case the manufacturer should material is used for signing. In this case the manufacturer should
perform the verification, because any release of the key material perform the verification, because any release of the key material
would enable a participant other than the entity to create valid would enable a participant other than the entity to create valid
signed EATs. signed EATs.
1.4. What is Not Standardized 1.4. What is Not Standardized
The following is not standardized for EAT, just the same they are not
standardized for CWT or JWT.
1.4.1. Transmission Protocol 1.4.1. Transmission Protocol
EATs may be transmitted by any protocol. For example, they might be EATs may be transmitted by any protocol the same as CWTs and JWTs.
added in extension fields of other protocols, bundled into an HTTP For example, they might be added in extension fields of other
header, or just transmitted as files. This flexibility is protocols, bundled into an HTTP header, or just transmitted as files.
intentional to allow broader adoption. This flexibility is possible This flexibility is intentional to allow broader adoption. This
because EAT's are self-secured with signing (and possibly flexibility is possible because EAT's are self-secured with signing
additionally with encryption and anti-replay). The transmission (and possibly additionally with encryption and anti-replay). The
protocol is not required to fulfill any additional security transmission protocol is not required to fulfill any additional
requirements. security requirements.
For certain devices, a direct connection may not exist between the For certain devices, a direct connection may not exist between the
EAT-producing device and the Relying Party. In such cases, the EAT EAT-producing device and the Relying Party. In such cases, the EAT
should be protected against malicious access. The use of COSE allows should be protected against malicious access. The use of COSE and
for signing and encryption of the EAT. Therefore even if the EAT is JOSE allows for signing and encryption of the EAT. Therefore, even
conveyed through intermediaries between the device and Relying Party, if the EAT is conveyed through intermediaries between the device and
such intermediaries cannot easily modify the EAT payload or alter the Relying Party, such intermediaries cannot easily modify the EAT
signature. payload or alter the signature.
1.4.2. Signing Scheme 1.4.2. Signing Scheme
The term "signing scheme" is used to refer to the system that The term "signing scheme" is used to refer to the system that
includes end-end process of establishing signing attestation key includes end-end process of establishing signing attestation key
material in the entity, signing the EAT, and verifying it. This material in the entity, signing the EAT, and verifying it. This
might involve key IDs and X.509 certificate chains or something might involve key IDs and X.509 certificate chains or something
similar but different. The term "signing algorithm" refers just to similar but different. The term "signing algorithm" refers just to
the algorithm ID in the COSE signing structure. No particular the algorithm ID in the COSE signing structure. No particular
signing algorithm or signing scheme is required by this standard. signing algorithm or signing scheme is required by this standard.
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There are three main implementation issues driving this. First, There are three main implementation issues driving this. First,
secure non-volatile storage space in the entity for the attestation secure non-volatile storage space in the entity for the attestation
key material may be highly limited, perhaps to only a few hundred key material may be highly limited, perhaps to only a few hundred
bits, on some small IoT chips. Second, the factory cost of bits, on some small IoT chips. Second, the factory cost of
provisioning key material in each chip or device may be high, with provisioning key material in each chip or device may be high, with
even millisecond delays adding to the cost of a chip. Third, even millisecond delays adding to the cost of a chip. Third,
privacy-preserving signing schemes like ECDAA (Elliptic Curve Direct privacy-preserving signing schemes like ECDAA (Elliptic Curve Direct
Anonymous Attestation) are complex and not suitable for all use Anonymous Attestation) are complex and not suitable for all use
cases. cases.
Eventually some form of standardization of the signing scheme may be Over time to faciliate interoperability, some signing schemes may be
required. This might come in the form of another standard that adds defined in EAT profiles or other documents either in the IETF or
to this document, or when there is clear convergence on a small outside.
number of signing schemes this standard can be updated.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This document reuses terminology from JWT [RFC7519], COSE [RFC8152], This document reuses terminology from JWT [RFC7519], COSE [RFC8152],
and CWT [RFC8392]. and CWT [RFC8392].
StringOrURI. The "StringOrURI" term in this specification has the
same meaning and processing rules as the JWT "StringOrURI" term
defined in Section 2 of [RFC7519], except that it is represented
as a CBOR text string instead of a JSON text string.
NumericDate. The "NumericDate" term in this specification has the
same meaning and processing rules as the JWT "NumericDate" term
defined in Section 2 of [RFC7519], except that it is represented
as a CBOR numeric date (from Section 2.4.1 of [RFC7049]) instead
of a JSON number. The encoding is modified so that the leading
tag 1 (epoch-based date/time) MUST be omitted.
Claim Name. The human-readable name used to identify a claim. Claim Name. The human-readable name used to identify a claim.
Claim Key. The CBOR map key used to identify a claim. Claim Key. The CBOR map key or JSON name used to identify a claim.
Claim Value. The CBOR map value representing the value of the claim.
CWT Claims Set. The CBOR map that contains the claims conveyed by Claim Value. The CBOR map or JSON object value representing the
the CWT. value of the claim.
FloatOrNumber. The "FloatOrNumber" term in this specification is the CWT Claims Set. The CBOR map or JSON object that contains the claims
type of a claim that is either a CBOR positive integer, negative conveyed by the CWT or JWT.
integer or floating point number.
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 3. The Claims Information Model
3.1. Universal Entity ID (UEID) Claim This section describes new claims defined for attestation. It also
mentions several claims defined by CWT and JWT are particularly
important for 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
[IANA.JWT.Claims] claims registries. * All claims are optional * No
claims are mandatory * All claims that are not understood by
implementations MUST be ignored
CDDL along with text descriptions is used to define the information
model. Each claim is defined as a CDDL group (the group is a general
aggregation and type definition feature of CDDL). In the data model,
described in the Section 4, the CDDL groups turn into CBOR map
entries and JSON name/value pairs.
3.1. Nonce Claim (cti and jti)
All EATs should have a nonce to prevent replay attacks. The nonce is
generated by the relying party, sent to the entity by any protocol,
and included in the token. Note that intrinsically by the nature of
a nonce no security is needed for its transport.
CWT defines the "cti" claim. JWT defines the "jti" claim. These
carry the nonce in an EAT.
TODO: what about the JWT claim "nonce"?
3.2. Timestamp claim (iat)
The "iat" claim defined in CWT and JWT is used to indicate the date-
of-creation of the token.
3.3. 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.
It is identified by Claim Key X (X is TBD).
UEID's must be universally and globally unique across manufacturers UEID's must be universally and globally unique across manufacturers
and countries. UEIDs must also be unique across protocols and and countries. UEIDs must also be unique across protocols and
systems, as tokens are intended to be embedded in many different systems, as tokens are intended to be embedded in many different
protocols and systems. No two products anywhere, even in completely protocols and systems. No two products anywhere, even in completely
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 different countries should have the same UEID (if they are not global
global and universal in this way then relying parties receiving them and universal in this way, then relying parties receiving them will
will have to track other characteristics of the device to keep have to track other characteristics of the device to keep devices
devices distinct between manufacturers). distinct between manufacturers).
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 binary byte-strings (resulting in a smaller size than text type byte and 256 bits). The recommended minimum is 17 bytes (1 type
strings). When handled in text-based protocols, they should be and 128 bits) because fewer bytes endanger the universal uniqueness.
base-64 encoded.
UEID's are variable length with a maximum size of 33 bytes (1 type
byte and 256 bits). A receivers of a token with UEIDs may reject the
token if a UEID is larger than 33 bytes.
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.
A UEID is a byte string. From the consumer's view (the rely party)
it is opaque with no bytes having any special meaning.
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].
+------+--------+---------------------------------------------------+ +------+--------+---------------------------------------------------+
| Type | Type | Specification | | Type | Type | Specification |
| Byte | Name | | | Byte | Name | |
+------+--------+---------------------------------------------------+ +------+--------+---------------------------------------------------+
| 0x01 | GUID | This is a 128 to 256 bit random number generated | | 0x01 | RAND | This is a 128- to 256-bit random number generated |
| | | once and stored in the device. The GUID may be | | | | once and stored in the device. This may be |
| | | constructed from various identifiers on the | | | | constructed by concatenating enough identifiers |
| | | device using a hash function or it may be just | | | | to be universally unique and then feeding the |
| | | the raw random number. | | | | concatenation through a cryptographic hash |
| | | function. It may also be a cryptographic quality |
| | | random number generate once at the beginning of |
| | | the life of the device and stored. |
| 0x02 | IEEE | This makes use of the IEEE company identification | | 0x02 | IEEE | This makes use of the IEEE company identification |
| | EUI | registry. An EUI is made up of an OUI and OUI-36 | | | EUI | registry. An EUI is made up of an OUI and OUI-36 |
| | | or a CID, different registered company | | | | or a CID, different registered company |
| | | identifiers, and some unique per-device | | | | identifiers, and some unique per-device |
| | | identifier. EUIs are often the same as or similar | | | | identifier. EUIs are often the same as or similar |
| | | to MAC addresses. (Note that while devices with | | | | to MAC addresses. (Note that while devices with |
| | | multiple network interfaces may have multiple MAC | | | | multiple network interfaces may have multiple MAC |
| | | addresses, there is only one UEID for a device) | | | | addresses, there is only one UEID for a device) |
| | | TODO: normative references to IEEE. | | | | TODO: normative references to IEEE. |
| 0x03 | IMEI | This is a 14-digit identifier consisting of an 8 | | 0x03 | IMEI | This is a 14-digit identifier consisting of an |
| | | digit Type Allocation Code and a six digit serial | | | | 8-digit Type Allocation Code and a 6-digit serial |
| | | number allocated by the manufacturer, which SHALL | | | | number allocated by the manufacturer, which SHALL |
| | | be encoded as a binary integer over 48 bits. The | | | | be encoded as a binary integer over 48 bits. The |
| | | IMEI value encoded SHALL NOT include Luhn | | | | IMEI value encoded SHALL NOT include Luhn |
| | | checksum or SVN information. | | | | checksum or SVN information. |
| 0x04 | EUI-48 | This is a 48-bit identifier formed by | | 0x04 | EUI-48 | This is a 48-bit identifier formed by |
| | | concatenating the 24-bit OUI with a 24-bit | | | | concatenating the 24-bit OUI with a 24-bit |
| | | identifier assigned by the organisation that | | | | identifier assigned by the organisation that |
| | | purchased the OUI. | | | | purchased the OUI. |
| 0x05 | EUI-60 | This is a 60-bit identifier formed by | | 0x05 | EUI-60 | This is a 60-bit identifier formed by |
| | | concatenating the 24-bit OUI with a 36-bit | | | | concatenating the 24-bit OUI with a 36-bit |
| | | identifier assigned by the organisation that | | | | identifier assigned by the organisation that |
| | | purchased the OUI. | | | | purchased the OUI. |
| 0x06 | EUI-64 | This is a 64-bit identifier formed by | | 0x06 | EUI-64 | This is a 64-bit identifier formed by |
| | | concatenating the 24-bit OUI with a 40-bit | | | | concatenating the 24-bit OUI with a 40-bit |
| | | identifier assigned by the organisation that | | | | identifier assigned by the organisation that |
| | | purchased the OUI. | | | | purchased the OUI. |
+------+--------+---------------------------------------------------+ +------+--------+---------------------------------------------------+
Table 1: UEID Composition Types Table 1: UEID Composition Types
The consumer (the Relying Party) of a UEID should treat a UEID as a 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 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 OUI claim that is defined elsewhere. The reasons
for this are: 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 0x04 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.
3.2. Origination (origination) Claims ### CDDL
ueid_claim = (
ueid: bstr )
3.4. 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 |
+-------------------+-----------------------------------------------+ +-------------------+-----------------------------------------------+
| Acme-TEE | The EATs are generated in the TEE authored | | Acme-TEE | The EATs are generated in the TEE authored |
| | and configured by "Acme" | | | and configured by "Acme" |
| Acme-TPM | The EATs are generated in a TPM manufactured | | Acme-TPM | The EATs are generated in a TPM manufactured |
| | by "Acme" | | | by "Acme" |
| Acme-Linux-Kernel | The EATs are generated in a Linux kernel | | Acme-Linux-Kernel | The EATs are generated in a Linux kernel |
| | configured and shipped by "Acme" | | | configured and shipped by "Acme" |
| 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" |
+-------------------+-----------------------------------------------+ +-------------------+-----------------------------------------------+
The claim is represented by Claim Key X+1. It is type StringOrURI.
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.
3.3. OEM identification by IEEE OUI 3.4.1. CDDL
origination_claim = (
origination: string_or_uri )
3.5. OEM identification by IEEE OUI (oemid)
This claim identifies a device OEM by the IEEE OUI. Reference TBD. This claim identifies a device OEM by the IEEE OUI. Reference TBD.
It is a byte string representing the OUI in binary form in network It is a byte string representing the OUI in binary form in network
byte order (TODO: confirm details). byte order (TODO: confirm details).
Companies that have more than one IEEE OUI registered with IEEE Companies that have more than one IEEE OUI registered with IEEE
should pick one and prefer that for all their devices. should pick one and prefer that for all their devices.
Note that the OUI is in common use as a part of MAC Address. This Note that the OUI is in common use as a part of MAC Address. This
claim is only the first bits of the MAC address that identify the claim is only the first bits of the MAC address that identify the
manufacturer. The IEEE maintains a registry for these in which many manufacturer. The IEEE maintains a registry for these in which many
companies participate. This claim is represented by Claim Key TBD. companies participate.
3.4. Security Level (seclevel) Claim 3.5.1. CDDL
oemid_claim = (
oemid: bstr )
3.6. 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 definied 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
reside and the claims originate. reside and the claims originate.
This claim is identified by Claim Key X+2. The value is an integer
between 1 and 4 as defined below.
1 - Unrestricted There is some expectation that implementor will 1 - Unrestricted There is some expectation that implementor will
protect the attestation signing keys at this level. Otherwise the protect the attestation signing keys at this level. Otherwise the
EAT provides no meaningful security assurances. EAT provides no meaningful security assurances.
2- Restricted Entities at this level should not be general-purpose 2- Restricted Entities at this level should not be general-purpose
operating environments that host features such as app download operating environments that host features such as app download
systems, web browsers and complex productivity applications. It systems, web browsers and complex productivity applications. It
is akin to the Secure Restricted level (see below) without the is akin to the Secure Restricted level (see below) without the
security orientation. Examples include a WiFi subsystem, an IoT security orientation. Examples include a Wi-Fi subsystem, an IoT
camera, or sensor device. camera, or sensor device.
3 - Secure Restricted Entities at this level must meet the critera 3 - Secure Restricted Entities at this level must meet the criteria
defined by FIDO Allowed Restricted Operating Environments (TODO: defined by FIDO Allowed Restricted Operating Environments (TODO:
reference). Examples include TEE's and schemes using reference). Examples include TEE's and schemes using
virtualization-based security. Like the FIDO security goal, virtualization-based security. Like the FIDO security goal,
security at this level is aimed at defending well against large- security at this level is aimed at defending well against large-
scale network / remote attacks against the device. scale network / remote attacks against the device.
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.
3.5. Nonce (nonce) Claim 3.6.1. CDDL
The "nonce" (Nonce) claim represents a random value that can be used security_level_type = (
to avoid replay attacks. This would be ideally generated by the CWT unrestricted: 1,
consumer. This value is intended to be a CWT companion claim to the restricted: 2,
existing JWT claim **_IANAJWT_ (TODO: fix this reference). The nonce secure_restricted: 3,
claim is identified by Claim Key X+3. hardware: 4
)
3.6. Secure Boot and Debug Enable State Claims security_level_claim = (
security_level: security_level_type )
3.6.1. Secure Boot Enabled (secbootenabled) Claim 3.7. Secure Boot and Debug Enable State Claims (boot_state)
The "secbootenabled" (Secure Boot Enabled) claim represents a boolean This claim is an array of five Boolean values indicating the boot and
value that indicates whether secure boot is enabled either for an debug state of the entity.
entire device or an individual submodule. If it appears at the
device level, then this means that secure boot is enabled for all 3.7.1. Secure Boot Enabled
This indicates whether secure boot is enabled either for an entire
device or an individual submodule. If it appears at the device
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
authenticate software running either in a device or a submodule prior authenticate software running either in a device or a submodule prior
allowing execution. This claim is identified by Claim Key X+4. allowing execution.
3.6.2. Debug Disabled (debugdisabled) Claim 3.7.2. Debug Disabled
The "debugdisabled" (Debug Disabled) claim represents a boolean value This indicates whether debug capabilities are disabled for an entity
that indicates whether debug capabilities are disabled for an entity
(i.e. value of 'true'). Debug disablement is considered a (i.e. value of 'true'). Debug disablement is considered a
prerequisite before an entity is considered operational. This claim prerequisite before an entity is considered operational.
is identified by Claim Key X+5.
3.6.3. Debug Disabled Since Boot (debugdisabledsincebboot) Claim
The "debugdisabledsinceboot" (Debug Disabled Since Boot) claim 3.7.3. Debug Disabled Since Boot
represents a boolean value that indicates whether debug capabilities
for the entity were not disabled in any way since boot (i.e. value of
'true'). This claim is identified by Claim Key X+6.
3.6.4. Debug Permanent Disable (debugpermanentdisable) Claim This claim indicates whether debug capabilities for the entity were
not disabled in any way since boot (i.e. value of 'true').
The "debugpermanentdisable" (Debug Permanent Disable) claim 3.7.4. Debug Permanent Disable
represents a boolean value that indicates whether debug capabilities
for the entity are permanently disabled (i.e. value of 'true'). This
value can be set to 'true' also if only the manufacturer is allowed
to enabled debug, but the end user is not. This claim is identified
by Claim Key X+7.
3.6.5. Debug Full Permanent Disable (debugfullpermanentdisable) Claim This claim indicates whether debug capabilities for the entity are
permanently disabled (i.e. value of 'true'). This value can be set
to 'true' also if only the manufacturer is allowed to enabled debug,
but the end user is not.
The "debugfullpermanentdisable" (Debug Full Permanent Disable) claim 3.7.5. Debug Full Permanent Disable
represents a boolean value that indicates whether debug capabilities
for the entity are permanently disabled (i.e. value of 'true'). This
value can only be 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 fuses cannot be restored once blown. This claim is
identified by Claim Key X+8.
3.7. Location (loc) Claim This claim indicates whether debug capabilities for the entity are
permanently disabled (i.e. value of 'true'). This value can only be
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
fuses cannot be restored once blown.
The "loc" (location) claim is a CBOR-formatted object that describes 3.7.6. CDDL
the location of the device entity from which the attestation
originates. It is identified by Claim Key X+10. It is comprised of
an array of additional subclaims that represent the actual location
coordinates (latitude, longitude and altitude). The location
coordinate claims are consistent with the WGS84 coordinate system
[WGS84]. In addition, a subclaim providing the estimated accuracy of
the location measurement is defined.
3.7.1. lat (latitude) claim boot_state_type = [
secure_boot_enabled=> bool,
debug_disabled=> bool,
debug_disabled_since_boot=> bool,
debug_permanent_disable=> bool,
debug_full_permanent_disable=> bool
]
The "lat" (latitude) claim contains the value of the device location boot_state_claim = (
corresponding to its latitude coordinate. It is of data type boot_state: boot_state_type
FloatOrNumber and identified by Claim Key X+11. )
3.7.2. long (longitude) claim 3.8. The Location Claim (location)
The "long" (longitude) claim contains the value of the device The location claim is a CBOR-formatted object that describes the
location corresponding to its longitude coordinate. It is of data location of the device entity from which the attestation originates.
type FloatOrNumber and identified by Claim Key X+12. It is comprised of a map of additional sub claims that represent the
actual location coordinates (latitude, longitude and altitude). The
location coordinate claims are consistent with the WGS84 coordinate
system [WGS84]. In addition, a sub claim providing the estimated
accuracy of the location measurement is defined.
3.7.3. alt (altitude) claim 3.8.1. CDDL
The "alt" (altitude) claim contains the value of the device location location_type = {
corresponding to its altitude coordinate (if available). It is of latitude => number,
data type FloatOrNumber and identified by Claim Key X+13. longitude => number,
altitude => number,
accuracy => number,
altitude_accuracy => number,
heading_claim => number,
speed_claim => number
}
3.7.4. acc (accuracy) claim location_claim = (
location: location_type )
The "acc" (accuracy) claim contains a value that describes the 3.9. The Age Claim (age)
location accuracy. It is non-negative and expressed in meters. It
is of data type FloatOrNumber and identified by Claim Key X+14.
3.7.5. altacc (altitude accuracy) claim The "age" claim contains a value that represents the number of
seconds that have elapsed since the token was created, measurement
was made, or location was obtained. Typical attestable values are
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
accurate time reference is unavailable for creation of a timestamp,
then the age claim is provided.
The "altacc" (altitude accuracy) claim contains a value that age_claim = (
describes the altitude accuracy. It is non-negative and expressed in age: uint)
meters. It is of data type FloatOrNumber and identified by Claim Key
X+15.
3.7.6. heading claim 3.10. The Uptime Claim (uptime)
The "heading" claim contains a value that describes direction of The "uptime" claim contains a value that represents the number of
motion for the entity. Its value is specified in degrees, between 0 seconds that have elapsed since the entity or submod was last booted.
and 360. It is of data type FloatOrNumber and identified by Claim
Key X+16.
3.7.7. speed claim 3.10.1. CDDL
The "speed" claim contains a value that describes the velocity of the uptime_claim = (
entity in the horizontal direction. Its value is specified in uptime: uint )
meters/second and must be non-negative. It is of data type
FloatOrNumber and identified by Claim Key X+17.
3.8. ts (timestamp) claim 3.11. Nested EATs, the EAT Claim (nested_eat)
The "ts" (timestamp) claim contains a timestamp derived using the It is allowed for one EAT to be embedded in another. This is for
same time reference as is used to generate an "iat" claim (see complex devices that have more than one subsystem capable of
Section 3.1.6 of [RFC8392]). It is of the same type as "iat" generating an EAT. Typically, one will be the device-wide EAT that
(integer or floating-point), and is identified by Claim Key X+18. It is low to medium security and another from a Secure Element or
is meant to designate the time at which a measurement was taken, when similar that is high security.
a location was obtained, or when a token was actually transmitted.
The timestamp would be included as a subclaim under the "submod" or
"loc" claims (in addition to the existing respective subclaims), or
at the device level.
3.9. age claim The contents of the "eat" claim must be a fully signed, optionally
encrypted, EAT token.
The "age" claim contains a value that represents the number of 3.11.1. CDDL
seconds that have elapsed since the token was created, measurement
was made, or location was obtained. Typical attestable values are
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
accurate time reference is unavailable for creation of a timestamp,
then the age claim is provided. It is identified by Claim Key X+19.
3.10. uptime claim nested_eat_claim = (
nested_eat: nested_eat_type)
The "uptime" claim contains a value that represents the number of A nested_eat_type is defined in words rather than CDDL. It is either
seconds that have elapsed since the entity or submod was last booted. a full CWT or JWT including the COSE or JOSE signing.
It is identified by Claim Key X+20.
3.11. The submods Claim 3.12. The Submods Claim (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., WiFi and cellular). It may have submodules for communications (e.g., Wi-Fi and cellular). It may
sub systems for low-power audio and video playback. It may have one have subsystems for low-power audio and video playback. It may have
or more security-oriented subsystems like a TEE or a Secure Element. one or more security-oriented subsystems like a TEE or a Secure
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 Specifically, the "submods" claim is an array. Each item in the
array is a CBOR map containing all the claims for a particular array is a CBOR map containing all the claims for a particular
submodule. It is identified by Claim Key X+22. submodule.
The security level of the submod is assumed to be at the same level The security level of the submod is assumed to be at the same level
as the main entity unless there is a security level claim in that as the main entity unless there is a security level claim in that
submodule indicating otherwise. The security level of a submodule submodule indicating otherwise. The security level of a submodule
can never be higher (more secure) than the security level of the EAT can never be higher (more secure) than the security level of the EAT
it is a part of. it is a part of.
3.11.1. The submod_name Claim 3.12.1. The submod_name Claim
Each submodule should have a submod_name claim that is descriptive Each submodule should have a submod_name claim that is descriptive
name. This name should be the CBOR txt type. name. This name should be the CBOR txt type.
3.11.2. Nested EATs, the eat Claim 3.12.2. CDDL
It is allowed for one EAT to be embedded in another. This is for In the following a generic_claim_type is any CBOR map entry or JSON
complex devices that have more than one subsystem capable of name/value pair.
generating an EAT. Typically one will 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 "eat" claim must be a fully signed, optionally submod_name_type = (
encrypted, EAT token. It is identified by Claim Key X+23. submod_name: tstr )
4. CBOR Interoperability submods_type = [ * submod_claims ]
EAT is a one-way protocol. It only defines a single message that submod_claims = {
goes from the entity to the server. The entity implementation will submod_name_type,
often be in a contained environment with little RAM and the server * generic_claim_type
will usually not be. The following requirements for interoperability }
take that into account. The entity can generally use whatever
encoding it wants. The server is required to support just about
every encoding.
Canonical CBOR encoding is explicitly NOT required as it would place submods_claim = (
an unnecessary burden on the entity implementation. submods: submod_type )
4.1. Integer Encoding (major type 0 and 1) 4. Data Model
The entity may use any integer encoding allowed by CBOR. The server This makes use of the types defined in CDDL Appendix D, Standard
MUST accept all integer encodings allowed by CBOR. Prelude.
4.2. String Encoding (major type 2 and 3) 4.1. Common CDDL Types
The entity can use any string encoding allowed by CBOR including string_or_uri = #6.32(tstr) / tstr; See JSON section below for JSON encoding of string_or_uri
indefinite lengths. It may also encode the lengths of strings in any
way allowed by CBOR. The server must accept all string encodings.
Major type 2, bstr, SHOULD be have tag 21, 22 or 23 to indicate 4.2. CDDL for CWT-defined Claims
conversion to base64 or such when converting to JSON.
4.3. Map and Array Encoding (major type 4 and 5) This section provides CDDL for the claims defined in CWT. It is non-
normative as [RFC8392] is the authoritative definition of these
claims.
The entity can use any array or map encoding allowed by CBOR cwt_claim = (
including indefinite lengths. Sorting of map keys is not required. issuer_claim //
Duplicate map keys are not allowed. The server must accept all array subject_claim //
and map encodings. The server may reject maps with duplicate map audience_claim //
keys. expiration_claim //
not_before_claim //
issued_at_calim //
cwt_id_claim
)
4.4. Date and Time issuer_claim = (
issuer: string_or_uri )
The entity should send dates as tag 1 encoded as 64-bit or 32-bit subject_claim = (
integers. The entity may not send floating point dates. The server subject: string_or_uri )
must support tag 1 epoch based dates encoded as 64-bit or 32-bit
integers.
The entity may send tag 0 dates, however tag 1 is preferred. The audience_claim = (
server must support tag 0 UTC dates. audience: string_or_uri )
4.5. URIs expiration_claim = (
expiration: time )
URIs should be encoded as text strings and marked with tag 32. not_before_claim = (
not_before: time )
4.6. Floating Point issued_at_calim = (
issued_at: time )
Encoding data in floating point is to be used only if necessary. cwt_id_claim = (
Location coordinates are always in floating point. The server must cwt_id: bstr )
support decoding of all types of floating point.
4.7. Other types issuer = 1
subject = 2
audience = 3
expiration = 4
not_before = 5
issued_at = 6
cwt_id = 7
Use of Other types like bignums, regular expressions and so SHOULD 4.3. JSON
NOT be used. The server MAY support them, but is not required to.
Use of these tags is 4.3.1. JSON Labels
ueid = "ueid"
origination = "origination"
oemid = "oemid"
security_level = "security_level"
boot_state = "boot_state"
location = "location"
age = "age"
uptime = "uptime"
nested_eat = "nested_eat"
submods = "submods"
4.3.2. JSON Interoperability
JSON should be encoded per RFC 8610 Appendix E. In addition, the
following CDDL types are encoded in JSON as follows:
o bstr - must be base64url encoded
o time - must be encoded as NumericDate as described section 2 of
[RFC7519].
o string_or_uri - must be encoded as StringOrURI as described
section 2 of [RFC7519].
4.4. CBOR
4.4.1. Labels
ueid = 8
origination = 9
oemid = 10
security_level = 11
boot_state = 12
location = 13
age = 14
uptime = 15
nested_eat = 16
submods = 17
submod_name = 18
latitude 1
longitude 2
altitude 3
accuracy 4
altitude_accuracy 5
heading_claim 6
speed_claim 7
4.4.2. CBOR Interoperability
Variations in the CBOR serializations supported in CBOR encoding and
decoding are allowed and suggests that CBOR-based protocols specify
how this variation is handled. This section specifies what formats
MUST be supported in order to achieve interoperability.
The assumption is that the entity is likely to be a constrained
device and relying party is likely to be a very capable server. The
approach taken is that the entity generating the token can use
whatever encoding it wants, specifically encodings that are easier to
implement such as indefinite lengths. The relying party receiving
the token must support decoding all encodings.
These rules cover all types used in the claims in this document.
They also are recommendations for additional claims.
Canonical CBOR encoding, Preferred Serialization and
Deterministically Encoded CBOR are explicitly NOT required as they
would place an unnecessary burden on the entity implementation,
particularly if the entity implementation is implemented in hardware.
o Integer Encoding (major type 0, 1) - The entity may use any
integer encoding allowed by CBOR. The server MUST accept all
integer encodings allowed by CBOR.
o String Encoding (major type 2 and 3) - The entity can use any
string encoding allowed by CBOR including indefinite lengths. It
may also encode the lengths of strings in any way allowed by CBOR.
The server must accept all string encodings.
o Major type 2, bstr, SHOULD be have tag 21 to indicate conversion
to base64url in case that conversion is performed.
o Map and Array Encoding (major type 4 and 5) - The entity can use
any array or map encoding allowed by CBOR including indefinite
lengths. Sorting of map keys is not required. Duplicate map keys
are not allowed. The server must accept all array and map
encodings. The server may reject maps with duplicate map keys.
o Date and Time - The entity should send dates as tag 1 encoded as
64-bit or 32-bit integers. The entity may not send floating-point
dates. The server must support tag 1 epoch-based dates encoded as
64-bit or 32-bit integers. The entity may send tag 0 dates,
however tag 1 is preferred. The server must support tag 0 UTC
dates.
o URIs - URIs should be encoded as text strings and marked with tag
32.
o Floating Point - The entity may use any floating-point encoding.
The relying party must support decoding of all types of floating-
point.
o Other types - Use of Other types like bignums, regular expressions
and such, SHOULD NOT be used. The server MAY support them but is
not required to so interoperability is not guaranteed.
4.5. Collected CDDL
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
* claim
}
claim = (
ueid_claim //
origination_claim //
oemid_claim //
security_level_claim //
boot_state_claim //
location_claim //
age_claim //
uptime_claim //
nested_eat_claim //
cwt_claim //
generic_claim_type //
)
TODO: copy the rest of the CDDL here (wait until the CDDL is more
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. New new IANA registry is created. All Claims Registry is re used. No new IANA registry is created. All
EAT claims should be registered in the CWT Claims Registry. EAT claims should be registered in the CWT and JWT Claims Registries.
5.1.1. Claims Registered by This Document 5.1.1. Claims Registered by This Document
o Claim Name: UEID o Claim Name: UEID
o Claim Description: The Universal Entity ID o Claim Description: The Universal Entity ID
o JWT Claim Name: N/A o JWT Claim Name: N/A
o Claim Key: X o Claim Key: 8
o Claim Value Type(s): byte string o Claim Value Type(s): byte string
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): *this document* o Specification Document(s): *this document*
TODO: add the rest of the claims in here TODO: add the rest of the claims in here
5.2. EAT CBOR Tag Registration
How an EAT consumer determines whether received CBOR-formatted data
actually represents a valid EAT is application-dependent, much like a
CWT. For instance, a specific MIME type associated with the EAT such
as "application/eat" could be sufficient for identification of the
EAT. Note however that EAT's can include other EAT's (e.g. a device
EAT comprised of several submodule EAT's). In this case, a CBOR tag
dedicated to the EAT will be required at least for the submodule
EAT's and the tag must be a valid CBOR tag. In other words - the EAT
CBOR tag can optionally prefix a device-level EAT, but a EAT CBOR tag
must always prefix a submodule EAT. The proposed EAT CBOR tag is 71.
5.2.1. Tag Registered by This Document
o CBOR Tag: 71
o Data Item: Entity Attestation Token (EAT)
o Semantics: Entity Attestation Token (CWT), as defined in
*this_doc*
o Reference: *this_doc*
o Point of Contact: Giridhar Mandyam, mandyam@qti.qualcomm.com
6. Privacy Considerations 6. Privacy Considerations
Certain EAT claims can be used to track the owner of an entity and Certain EAT claims can be used to track the owner of an entity and
therefore implementations should consider providing privacy- therefore, implementations should consider providing privacy-
preserving options dependent on the intended usage of the EAT. preserving options dependent on the intended usage of the EAT.
Examples would include suppression of location claims for EAT's Examples would include suppression of location claims for EAT's
provided to unauthenticated consumers. provided to unauthenticated consumers.
6.1. UEID Privacy Considerations 6.1. UEID Privacy Considerations
A UEID is usually not privacy preserving. Any set of relying parties A UEID is usually not privacy-preserving. Any set of relying parties
that receives tokens that happen to be from a single device will be that receives tokens that happen to be from a single device will be
able to know the tokens are all from the same device and be able to able to know the tokens are all from the same device and be able to
track the device. Thus, in many usage situations ueid violates track the device. Thus, in many usage situations ueid violates
governmental privacy regulation. In other usage situations UEID will governmental privacy regulation. In other usage situations UEID will
not be allowed for certain products like browsers that give privacy not be allowed for certain products like browsers that give privacy
for the end user. it will often be the case that tokens will not for the end user. it will often be the case that tokens will not
have a UEID for these reasons. have a UEID for these reasons.
There are several strategies that can be used to still be able to put There are several strategies that can be used to still be able to put
UEID's in tokens: UEID's in tokens:
skipping to change at page 20, line 15 skipping to change at page 23, line 28
7. Security Considerations 7. Security Considerations
TODO: Perhaps this can be the same as CWT / COSE, but not sure yet TODO: Perhaps this can be the same as CWT / COSE, but not sure yet
because it involves so much entity / device security that those do because it involves so much entity / device security that those do
not. not.
8. References 8. References
8.1. Normative References 8.1. Normative References
[IANA.CWT.Claims]
IANA, "CBOR Web Token (CWT) Claims", n.d.,
<http://www.iana.org/assignments/cwt>.
[IANA.JWT.Claims]
IANA, "JSON Web Token (JWT) Claims", n.d.,
<https://www.iana.org/assignments/jwt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>. October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>. <https://www.rfc-editor.org/info/rfc7519>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017, RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>. <https://www.rfc-editor.org/info/rfc8152>.
[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>.
[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
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[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.
[ECMAScript]
"Ecma International, "ECMAScript Language Specification,
5.1 Edition", ECMA Standard 262", June 2011,
<http://www.ecma-international.org/ecma-262/5.1/
ECMA-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>.
[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 / 11:h'948f8860d13a463e8e', / nonce (cti) / 7:h'948f8860d13a463e8e',
/ UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f', / UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f',
/ secbootenabled / 13:true, / boot_state / 12:{true, true, true, true, false}
/ debugpermanentdisable / 15:true, / time stamp (iat) / 6:1526542894,
/ ts / 21:1526542894,
} }
A.2. Example with Submodules, Nesting and Security Levels A.2. Example with Submodules, Nesting and Security Levels
{ {
/ nonce / 11:h'948f8860d13a463e8e', / nonce / 7:h'948f8860d13a463e8e',
/ UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f', / UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f',
/ secbootenabled / 13:true, / boot_state / 12:{true, true, true, true, false}
/ debugpermanentdisable / 15:true, / time stamp (iat) / 6:1526542894,
/ ts / 21:1526542894, / seclevel / 11:3, / secure restricted OS /
/ seclevel / 10:3, / secure restriced OS /
/ submods / 30: / submods / 17:
[ [
/ 1st submod, an Android Application / { / 1st submod, an Android Application / {
/ submod_name / 30:'Android App "Foo"', / submod_name / 18:'Android App "Foo"',
/ seclevel / 10:1, / 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 / {
/ submod_name / 30:'Secure Element EAT', / submod_name / 18:'Secure Element EAT',
/ eat / 31:71( 18( / eat / 16:61( 18(
/ an embedded EAT / [ /...COSE_Sign1 bytes with payload.../ ] / an embedded EAT / [ /...COSE_Sign1 bytes with payload.../ ]
)) ))
} }
/ 3rd submod, information about Linux Android / { / 3rd submod, information about Linux Android / {
/ submod_name/ 30:'Linux Android', / submod_name/ 18:'Linux Android',
/ seclevel / 10:1, / unrestricted / / seclevel / 11:1, / unrestricted /
/ custom - release / -80000:'8.0.0', / custom - release / -80000:'8.0.0',
/ custom - version / -80001:'4.9.51+' / custom - version / -80001:'4.9.51+'
} }
] ]
} }
Appendix B. Changes from 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
the significant differences.
B.1. From draft-mandyam-rats-eat-00
This is a fairly large change in the orientation of the document, but
not new claims have been added.
o Separate information and data model using CDDL.
o Say an EAT is a CWT or JWT
o Use a map to structure the boot_state and location claims
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. 126 change blocks. 
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