[Docs] [txt|pdf] [Tracker] [Email] [Nits]

Versions: 00

Network Working Group                                         G. Mandyam
Internet-Draft                                              L. Lundblade
Intended status: Standards Track                          M. Ballesteros
Expires: November 20, 2018                                 J. O'Donoghue
                                              Qualcomm Technologies Inc.
                                                            May 19, 2018


                   The Entity Attestation Token (EAT)
                          draft-mandyam-eat-00

Abstract

   An attestation format based on concise binary object representation
   (CBOR) is proposed that is suitable for inclusion in a CBOR Web Token
   (CWT), know as the Entity Attestation Token (EAT).  The associated
   data can be used by a relying party to assess the security state of a
   remote device or module.

Contributing

   TBD

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 20, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of



Mandyam, et al.         Expires November 20, 2018               [Page 1]


Internet-Draft                     EAT                          May 2018


   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Entity Overview . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Use of CBOR and COSE  . . . . . . . . . . . . . . . . . .   4
     1.3.  EAT Operating Models  . . . . . . . . . . . . . . . . . .   5
     1.4.  What is Not Standardized  . . . . . . . . . . . . . . . .   6
       1.4.1.  Transmission Protocol . . . . . . . . . . . . . . . .   6
       1.4.2.  Signing Scheme  . . . . . . . . . . . . . . . . . . .   6
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   7
   3.  The Claims  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     3.1.  Universal Entity ID (UEID) Claim  . . . . . . . . . . . .   8
     3.2.  Origination (origination) Claims  . . . . . . . . . . . .  10
     3.3.  OEM identification by IEEE OUI  . . . . . . . . . . . . .  10
     3.4.  Security Level (seclevel) Claim . . . . . . . . . . . . .  11
     3.5.  Nonce (nonce) Claim . . . . . . . . . . . . . . . . . . .  12
     3.6.  Secure Boot and Debug Enable State Claims . . . . . . . .  12
       3.6.1.  Secure Boot Enabled (secbootenabled) Claim  . . . . .  12
       3.6.2.  Debug Disabled (debugdisabled) Claim  . . . . . . . .  12
       3.6.3.  Debug Disabled Since Boot (debugdisabledsincebboot)
               Claim . . . . . . . . . . . . . . . . . . . . . . . .  12
       3.6.4.  Debug Permanent Disable (debugpermanentdisable) Claim  12
       3.6.5.  Debug Full Permanent Disable
               (debugfullpermanentdisable) Claim . . . . . . . . . .  13
     3.7.  Location (loc) Claim  . . . . . . . . . . . . . . . . . .  13
       3.7.1.  lat (latitude) claim  . . . . . . . . . . . . . . . .  13
       3.7.2.  long (longitude) claim  . . . . . . . . . . . . . . .  13
       3.7.3.  alt (altitude) claim  . . . . . . . . . . . . . . . .  13
       3.7.4.  acc (accuracy) claim  . . . . . . . . . . . . . . . .  13
       3.7.5.  altacc (altitiude accuracy) claim . . . . . . . . . .  14
       3.7.6.  heading claim . . . . . . . . . . . . . . . . . . . .  14
       3.7.7.  speed claim . . . . . . . . . . . . . . . . . . . . .  14
     3.8.  ts (timestamp) claim  . . . . . . . . . . . . . . . . . .  14
     3.9.  age claim . . . . . . . . . . . . . . . . . . . . . . . .  14
     3.10. uptime claim  . . . . . . . . . . . . . . . . . . . . . .  14
     3.11. The submods Claim . . . . . . . . . . . . . . . . . . . .  15
       3.11.1.  The submod_name Claim  . . . . . . . . . . . . . . .  15
       3.11.2.  Nested EATs, the eat Claim . . . . . . . . . . . . .  15
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
     4.1.  Reuse of CBOR Web Token (CWT) Claims Registry . . . . . .  15
       4.1.1.  Claims Registered by This Document  . . . . . . . . .  16



Mandyam, et al.         Expires November 20, 2018               [Page 2]


Internet-Draft                     EAT                          May 2018


     4.2.  EAT CBOR Tag Registration . . . . . . . . . . . . . . . .  16
       4.2.1.  Tag Registered by This Document . . . . . . . . . . .  16
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  17
     5.1.  UEID Privacy Considerations . . . . . . . . . . . . . . .  17
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  18
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  19
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .  20
     A.1.  Very Simple EAT . . . . . . . . . . . . . . . . . . . . .  20
     A.2.  Example with Submodules, Nesting and Security Levels  . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   Remote device attestation is fundamental service that allows a remote
   device such as a mobile phone, an Internet-of-Things (IoT) device, or
   other endpoint to prove itself to a relying party, a server or a
   service.  This allows the relying party to know some characteristics
   about the device and decide whether it trusts the device.

   Remote attestation is a fundamental service that can underly other
   protocols and services that need to know about the trustworthiness of
   the device before proceeding.  One good example is biometric
   authentication where the biometric matching is done on the device.
   The relying party needs to know that the device is one that is known
   to do biometric matching correctly.  Another example is content
   protection where the relying party wants to know the device will
   protect the data.  This generalizes on to corporate enterprises that
   might want to know that a device is trustworthy before allowing
   corporate data to be accessed by it.

   The notion of attestation here is large and may include, but is not
   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 processor, particularly
      for security oriented chips

   o  Measurement of the software (SW) running on the device

   o  Configuration and state of the device

   o  Environmental characteristics of the device such as its GPS
      location





Mandyam, et al.         Expires November 20, 2018               [Page 3]


Internet-Draft                     EAT                          May 2018


   The required data format should be general purpose and extensible so
   that it can work across many use cases.  This is why CBOR (see
   [RFC7049]) is choosen 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 "entity" can be any device or device subassembly ("submodule")
   that can generate its own attestation in the form of an EAT.  The
   attestation should be cryptographically verifiable by the EAT
   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
   EAT does so by means of a dedicated root-of-trust (RoT).

   Modern devices such as a mobile phone have many different execution
   environments operating with different security levels.  For example
   it is common for a mobile phone to have an "apps" environment that
   runs an operating system (OS) that hosts a plethora of downloadable
   apps.  It may also have a TEE (Trusted Execution Environment) that is
   distinct, isolated, and hosts security-oriented functionality like
   biometric authentication.  Additionally it may have an eSE (embedded
   Secure Element) - a high security chip with defenses against HW
   attacks that can serve as a RoT.  This device attestation format
   allows the attested data to be tagged at a security level from which
   it originates.  In general, any discrete execution environment that
   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.




Mandyam, et al.         Expires November 20, 2018               [Page 4]


Internet-Draft                     EAT                          May 2018


   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

   At least the following three participants exist in all EAT operating
   models.  Some operating models have additional participants.

   The Entity.  This is the phone, the IoT device, the sensor, the sub-
      assembly or such that the attestation provides information about.

   The Manufacturer.  The company that made the entity.  This may be a
      chip vendor, a circuit board module vendor or a vendor of finished
      consumer products.

   The Relying Party.  The server, service or company that makes use of
      the information in the EAT about the entity.

   In all operating models, the manufacturer provisions some secret
   attestation key material (AKM) into the entity during manufacturing.
   This might be during the manufacturer of a chip at a fabrication
   facility (fab) or during final assembly of a consumer product or any
   time in between.  This attestation key material is used for signing
   EATs.

   In all operating models, hardware and/or software on the entity
   create an EAT of the format described in this document.  The EAT is
   always signed by the attestation key material provisioned by the
   manufacturer.

   In all operating models, the relying party must end up knowing that
   the signature on the EAT is valid and consistent with data from
   claims in the EAT.  This can happen in many different ways.  Here are
   some examples.

   o  The EAT is transmitted to the relying party.  The relying party
      gets corresponding key material (e.g. a root certificate) from the
      manufacturer.  The relying party performs the verification.

   o  The EAT is transmitted to the relying party.  The relying party
      transmits the EAT to a verification service offered by the
      manufacturer.  The server returns the validated claims.

   o  The EAT is transmitted directly to a verification service, perhaps
      operated by the manufacturer or perhaps by another party.  It
      verifies the EAT and makes the validated claims available to the



Mandyam, et al.         Expires November 20, 2018               [Page 5]


Internet-Draft                     EAT                          May 2018


      relying party.  It may even modify the claims in some way and re-
      sign the EAT (with a different signing key).

   This standard supports all these operating models and does not prefer
   one over the other.  It is important to support this variety of
   operating models to generaly facilitate deployment and to allow for
   some special scenarios.  One special scenario has a validation
   service that is monetized, most likely by the manufacturer.  In
   another, a privacy proxy service processes the EAT before it is
   transmitted to the relying party.  In yet another, symmetric key
   material is used for signing.  In this case the manufacturer should
   perform the verification, because any release of the key material
   would enable a participant other than the entity to create valid
   signed EATs.

1.4.  What is Not Standardized

1.4.1.  Transmission Protocol

   EATs may be transmitted by any protocol.  For example, they might be
   added in extension fields of other protocols, bundled into an HTTP
   header, or just transmitted as files.  This flexibility is
   intentional to allow broader adoption.  This flexibility is possible
   because EAT's are self-secured with signing (and possibly
   additionally with encryption and anti-replay).  The transmission
   protocol is not required to fulfill any additional security
   requirements.

   For certain devices, a direct connection may not exist between the
   EAT-producing device and the Relying Party.  In such cases, the EAT
   should be protected against malicious access.  The use of COSE allows
   for signing and encryption of the EAT.  Therefore even if the EAT is
   conveyed through intermediaries between the device and Relying Party,
   such intermediaries cannot easily modify the EAT payload or alter the
   signature.

1.4.2.  Signing Scheme

   The term "signing scheme" is used to refer to the system that
   includes end-end process of establishing signing attesation key
   material in the entity, signing the EAT, and verifying it.  This
   might involve key IDs and X.509 certificate chains or something
   similar but different.  The term "signing algorithm" refers just to
   the algorithm ID in the COSE signing structure.  No particular
   signing algorithm or signing scheme is required by this standard.

   There are three main implementation issues driving this.  First,
   secure non-volatile storage space in the entity for the attestation



Mandyam, et al.         Expires November 20, 2018               [Page 6]


Internet-Draft                     EAT                          May 2018


   key material may be highly limited, perhaps to only a few hundred
   bits, on some small IoT chips.  Second, the factory cost of
   provisioning key material in each chip or device may be high, with
   even millisecond delays adding to the cost of a chip.  Third,
   privacy-preserving signing schemes like ECDAA (Elliptic Curve Direct
   Anonymous Attestation) are complex and not suitable for all use
   cases.

   Eventually some form of standardization of the signing scheme may be
   required.  This might come in the form of another standard that adds
   to this document, or when there is clear convergence on a small
   number of signing schemes this standard can be updated.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This document reuses terminology from JWT [RFC7519], COSE [RFC8152],
   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 Key.  The CBOR map key 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
      the CWT.

   FloatOrNumber.  The "FloatOrNumber" term in this specification is the
      type of a claim that is either a CBOR postivie integer, negative
      integer or floating point number.



Mandyam, et al.         Expires November 20, 2018               [Page 7]


Internet-Draft                     EAT                          May 2018


   Attestation Key Material (AKM).  The key material used to sign the
      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
      DevID [IDevID], then this is the private part of the EC key pair.
      If ECDAA is used, (e.g., as used by Ehnaced Privacy ID, i.e. EPID)
      then it is the key material needed for ECDAA.

3.  The Claims

3.1.  Universal Entity ID (UEID) Claim

   UEID's identify individual manufactured entities / devices such as a
   mobile phone, a water meter, a Bluetooth speaker or a networked
   security camera.  It may identify the entire device or a submodule or
   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
   sequential.

   It is identified by Claim Key X (X is TBD).

   UEID's must be universally and globally unique across manufacturers
   and countries.  UEIDs must also be unique across protocols and
   systems, as tokens are intended to be embedded in many different
   protocols and systems.  No two products anywhere, even in completely
   different industries made by two different manufacturers in two
   different countries. should have the same UEID (if they are not
   global and universal in this way then relying parties receiving them
   will have to track other characteristics of the device to keep
   devices distinct between manufacturers).

   The UEID should be permanent.  It should never change for a given
   device / entity.  In addition, it should not be reprogrammable.

   UEID's are binary byte-strings (resulting in a smaller size than text
   strings).  When handled in text-based protocols, they should be
   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 wtih no bytes having any special meaning.





Mandyam, et al.         Expires November 20, 2018               [Page 8]


Internet-Draft                     EAT                          May 2018


   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
   accommodate different industries and different manufacturing
   processes and to give options to avoid paying fees for certain types
   of manufacturer registrations.

   +------+------+-----------------------------------------------------+
   | Type | Type | Specification                                       |
   | Byte | Name |                                                     |
   +------+------+-----------------------------------------------------+
   | 0x01 | GUID | This is a 128 to 256 bit random number generated    |
   |      |      | once and stored in the device. The GUID may be      |
   |      |      | constructed from various identifiers on the device  |
   |      |      | using a hash function or it may be just the raw     |
   |      |      | random number. In any case, the random number must  |
   |      |      | have entropy of at least 128 bits as this is what   |
   |      |      | gives the global                                    |
   | 0x02 | IEEE | This makes use of the IEEE company identification   |
   |      | EUI  | registry. An EUI is made up of an OUI and OUI-36 or |
   |      |      | a CID, different registered company identifiers,    |
   |      |      | and some unique per-device identifier. EUIs are     |
   |      |      | often the same as or similar to MAC addresses.      |
   |      |      | (Note that while devices with multiple network      |
   |      |      | interfaces may have multiple MAC addresses, there   |
   |      |      | is only one UEID for a device) TODO: normative      |
   |      |      | references to IEEE.                                 |
   | 0x03 | IMEI | TODO: figure how to specify IMEIs                   |
   +------+------+-----------------------------------------------------+

                      Table 1: UEID Composition Types

   The consumer (the Relying Party) of a UEID should treat a UEID as a
   completely opaque string of bytes and not make any use of its
   internal structure.  For example they should not use the OUI part of
   a type 0x02 UEID to identify the manufacturer of the device.  Instead
   they should use the OUI claim that is defined elsewhere.  The reasons
   for this are:

   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
      may be created based on some other manufacturer registration
      scheme.

   o  Device manufacturers are allowed to change from one type of UEID
      to another anytime they want.  For example they may find they can
      optimize their manufacturing by switching from type 0x01 to type




Mandyam, et al.         Expires November 20, 2018               [Page 9]


Internet-Draft                     EAT                          May 2018


      0x02 or vice versa.  The main requirement on the manufacturer is
      that UEIDs be universally unique.

3.2.  Origination (origination) Claims

   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
   manufacturer.  The following table gives some examples:

   +-------------------+-----------------------------------------------+
   | Name              | Description                                   |
   +-------------------+-----------------------------------------------+
   | Acme-TEE          | The EATs are generated in the TEE authored    |
   |                   | and configured by "Acme"                      |
   | Acme-TPM          | The EATs are generated in a TPM manufactured  |
   |                   | by "Acme"                                     |
   | Acme-Linux-Kernel | The EATs are generated in a Linux kernel      |
   |                   | configured and shipped by "Acme"              |
   | Acme-TA           | The EATs are generated in a Trusted           |
   |                   | Application (TA) authored by "Acme"           |
   +-------------------+-----------------------------------------------+

   The claim is represented by Claim Key X+15.  It is type StringOrURI.

   TODO: consider a more structure approach where the name and the URI
   and other are in separate fields.

   TODO: This needs refinement.  It is somewhat parallel to issuer claim
   in CWT in that it describes the authority that created the token.

3.3.  OEM identification by IEEE OUI

   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
   byte order (TODO: confirm details).

   Companies that have more than one IEEE OUI registered with IEEE
   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
   claim is only the first bits of the MAC address that identify the
   manufacturer.  The IEEE maintains a registry for these in which many
   companies participate.  This claim is represented by Claim Key TBD.








Mandyam, et al.         Expires November 20, 2018              [Page 10]


Internet-Draft                     EAT                          May 2018


3.4.  Security Level (seclevel) Claim

   EATs have a claim that roughly characterizes the device / entities
   ability to defend against attacks aimed at capturing the signing key,
   forging claims and at forging EATs.  This is done by roughly defining
   four security levels as described below.  This is similar to the
   security levels defined in the Metadata Service definied by the Fast
   Identity Online (FIDO) Alliance (TODO: reference).

   These claims describe security environment and countermeasures
   available on the end-entity / client device where the attestation key
   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
      protect the attestation signing keys at this level.  Otherwise the
      EAT provides no meaningful security assurances.

   2- Restricted  Entities at this level should not be general-purpose
      operating environments that host features such as app download
      systems, web browsers and complex productivity applications.  It
      is akin to the Secure Restricted level (see below) without the
      security orientation.  Examples include a WiFi subsystem, an IoT
      camera, or sensor device.

   3 - Secure Restriced  Entities at this level must meet the critera
      defined by FIDO Allowed Restricted Operating Environments (TODO:
      reference).  Examples include TEE's and schemes using
      virtualization-based security.  Like the FIDO security goal,
      security at this level is aimed at defending well against large-
      scale network / remote attacks against the device.

   4 - Hardware  Entities at this level must include substantial defense
      against physical or electrical attacks against the device itself.
      It is assumed any potential attacker has captured the device and
      can disassemble it.  Example include TPMs and Secure Elements.

   This claim is not intended as a replacement for a proper end-device
   security certification schemes such as those based on FIPS (TODO:
   reference) or those based on Common Criterion (TODO: reference).  The
   claim made here is solely a self-claim made by the Entity Originator.








Mandyam, et al.         Expires November 20, 2018              [Page 11]


Internet-Draft                     EAT                          May 2018


3.5.  Nonce (nonce) Claim

   The "nonce" (Nonce) claim represents a random value that can be used
   to avoid replay attacks.  This would be ideally generated by the CWT
   consumer.  This value is intended to be a CWT companion claim to the
   existing JWT claim **_IANAJWT_ (TODO: fix this reference).  The nonce
   claim is identified by Claim Key X+3.

3.6.  Secure Boot and Debug Enable State Claims

3.6.1.  Secure Boot Enabled (secbootenabled) Claim

   The "secbootenabled" (Secure Boot Enabled) claim represents a boolean
   value that 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
   authenticate software running either in a device or a submodule prior
   allowing execution.  This claim is identified by Claim Key X+4.

3.6.2.  Debug Disabled (debugdisabled) Claim

   The "debugdisabled" (Debug Disabled) claim represents a boolean value
   that indicates whether debug capabilities are disabled for an entity
   (i.e. value of 'true').  Debug disablement is considered a
   prerequisite before an entity is considered operational.  This claim
   is identified by Claim Key X+5.

3.6.3.  Debug Disabled Since Boot (debugdisabledsincebboot) Claim

   The "debugdisabledsinceboot" (Debug Disabled Since Boot) claim
   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

   The "debugpermanentdisable" (Debug Permanent Disable) claim
   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.








Mandyam, et al.         Expires November 20, 2018              [Page 12]


Internet-Draft                     EAT                          May 2018


3.6.5.  Debug Full Permanent Disable (debugfullpermanentdisable) Claim

   The "debugfullpermanentdisable" (Debug Full Permanent Disable) claim
   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

   The "loc" (location) claim is a CBOR-formatted object that describes
   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

   The "lat" (latitude) claim contains the value of the device location
   corresponding to its latitude coordinate.  It is of data type
   FloatOrNumber and identified by Claim Key X+11.

3.7.2.  long (longitude) claim

   The "long" (longitude) claim contains the value of the device
   location corresponding to its longitude coordinate.  It is of data
   type FloatOrNumber and identified by Claim Key X+12.

3.7.3.  alt (altitude) claim

   The "alt" (altitude) claim contains the value of the device location
   corresponding to its altitude coordinate (if available).  It is of
   data type FloatOrNumber and identified by Claim Key X+13.

3.7.4.  acc (accuracy) claim

   The "acc" (accuracy) claim contains a value that describes the
   location accuracy.  It is non-negative and expressed in meters.  It
   is of data type FloatOrNumber and identified by Claim Key X+14.







Mandyam, et al.         Expires November 20, 2018              [Page 13]


Internet-Draft                     EAT                          May 2018


3.7.5.  altacc (altitiude accuracy) claim

   The "altacc" (altitude accuracy) claim contains a value that
   describes the altitude accuracy.  It is non-negative and expressed in
   meters.  It is of data type FloatOrNumber and identified by Claim Key
   X+15.

3.7.6.  heading claim

   The "heading" claim contains a value that describes direction of
   motion for the entity.  Its value is specified in degrees, between 0
   and 360.  It is of data type FloatOrNumber and identified by Claim
   Key X+16.

3.7.7.  speed claim

   The "speed" claim contains a value that describes the velocity of the
   entity in the horizontal direction.  Its value is specified in
   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

   The "ts" (timestamp) claim contains a timestamp derived using the
   same time reference as is used to generate an "iat" claim (see
   Section 3.1.6 of [RFC8392]).  It is of the same type as "iat"
   (integer or floating-point), and is identified by Claim Key X+18.  It
   is meant to designate the time at which a measurement was taken, when
   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 "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.  It is identified by Claim Key X+19.

3.10.  uptime claim

   The "uptime" claim contains a value that represents the number of
   seconds that have elapsed since the entity or submod was last booted.
   It is identified by Claim Key X+20.



Mandyam, et al.         Expires November 20, 2018              [Page 14]


Internet-Draft                     EAT                          May 2018


3.11.  The submods Claim

   Some devices are complex, having many subsystems or submodules.  A
   mobile phone is a good example.  It may have several connectivity
   submodules for communications (e.g., WiFi and celluar).  It may have
   sub systems for low-power audio and video playback.  It may have 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.

   Specifically, the "submods" claim is an array.  Each item in the
   array is a CBOR map containing all the claims for a particular
   submodule.  It is identified by Claim Key X+22.

   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
   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.

3.11.1.  The submod_name Claim

   Each submodule should have a submod_name claim that is descriptive
   name.  This name should be the CBOR txt type.

3.11.2.  Nested EATs, the eat Claim

   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.  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
   encrypted, EAT token.  It is identified by Claim Key X+23.

4.  IANA Considerations

4.1.  Reuse of CBOR Web Token (CWT) Claims Registry

   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
   EAT claims should be registered in the CWT Claims Registry.








Mandyam, et al.         Expires November 20, 2018              [Page 15]


Internet-Draft                     EAT                          May 2018


4.1.1.  Claims Registered by This Document

   o  Claim Name: UEID

   o  Claim Description: The Universal Entity ID

   o  JWT Claim Name: N/A

   o  Claim Key: X

   o  Claim Value Type(s): byte string

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   TODO: add the rest of the claims in here

4.2.  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.

4.2.1.  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








Mandyam, et al.         Expires November 20, 2018              [Page 16]


Internet-Draft                     EAT                          May 2018


5.  Privacy Considerations

   Certain EAT claims can be used to track the owner of an entity and
   therefore implementations should consider providing privacy-
   preserving options dependent on the intended usage of the EAT.
   Examples would include suppresion of location claims for EAT's
   provided to unauthenticated consumers.

5.1.  UEID Privacy Considerations

   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
   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
   governmental privacy regulation.  In other usage situations UEID will
   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
   have a UEID for these reasons.

   There are several strategies that can be used to still be able to put
   UEID's in tokens:

   o  The device obtains explicit permission from the user of the device
      to use the UEID.  This may be through a prompt.  It may also be
      through a license agreement.  For example, agreements for some
      online banking and brokerage services might already cover use of a
      UEID.

   o  The UEID is used only in a particular context or particular use
      case.  It is used only by one relying party.

   o  The device authenticates the relying party and generates a
      derivate UEID just for that particular relying party.  For
      example, the relying party could prove their identity
      cryptographically to the device, then the device generates a UEID
      just for that relying party by hashing a proofed relying party ID
      with the main device UEID.

   Note that some of these privacy preservation strategies result in
   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
   relying party, there is just one UEID and it is still globally
   universal across manufacturers.








Mandyam, et al.         Expires November 20, 2018              [Page 17]


Internet-Draft                     EAT                          May 2018


6.  Security Considerations

   TODO: Perhpas this can be the same as CWT / COSE, but not sure yet
   because it involves so much entity / device security that those do
   not.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7049]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
              October 2013, <https://www.rfc-editor.org/info/rfc7049>.

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/info/rfc7519>.

   [RFC8152]  Schaad, J., "CBOR Object Signing and Encryption (COSE)",
              RFC 8152, DOI 10.17487/RFC8152, July 2017,
              <https://www.rfc-editor.org/info/rfc8152>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8392]  Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
              "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
              May 2018, <https://www.rfc-editor.org/info/rfc8392>.

   [TIME_T]   The Open Group Base Specifications, "Vol. 1: Base
              Definitions, Issue 7", Section 4.15 'Seconds Since the
              Epoch', IEEE Std 1003.1, 2013 Edition, 2013,
              <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/
              V1_chap04.html#tag_04_15>.

   [WGS84]    National Imagery and Mapping Agency, "National Imagery and
              Mapping Agency Technical Report 8350.2, Third Edition",
              2000, <http://earth-
              info.nga.mil/GandG/publications/tr8350.2/wgs84fin.pdf>.






Mandyam, et al.         Expires November 20, 2018              [Page 18]


Internet-Draft                     EAT                          May 2018


7.2.  Informative References

   [ASN.1]    International Telecommunication Union, "Information
              Technology -- ASN.1 encoding rules: Specification of Basic
              Encoding Rules (BER), Canonical Encoding Rules (CER) and
              Distinguished Encoding Rules (DER)", ITU-T Recommendation
              X.690, 1994.

   [IDevID]   "IEEE Standard, "IEEE 802.1AR Secure Device Identifier"",
              December 2009, <http://standards.ieee.org/findstds/
              standard/802.1AR-2009.html>.

   [Webauthn]
              Worldwide Web Consortium, "Web Authentication: A Web API
              for accessing scoped credentials", 2016.




































Mandyam, et al.         Expires November 20, 2018              [Page 19]


Internet-Draft                     EAT                          May 2018


Appendix A.  Examples

A.1.  Very Simple EAT

   This is shown in CBOR diagnostic form.  Only the payload signed by
   COSE is shown.

{
   / nonce /                 11:h'948f8860d13a463e8e',
   / UEID /                   8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f',
   / secbootenabled /        13:true,
   / debugpermanentdisable / 15:true,
   / ts /                    21:1526542894,
}

A.2.  Example with Submodules, Nesting and Security Levels

{
   / nonce /                 11:h'948f8860d13a463e8e',
   / UEID /                   8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f',
   / secbootenabled /        13:true,
   / debugpermanentdisable / 15:true,
   / ts /                    21:1526542894,
   / seclevel /              10:3, / secure restriced OS /

   / submods / 30:
      [
         / 1st submod, an Android Application / {
           / submod_name /   30:'Android App "Foo"',
           / seclevel /      10:1, / unrestricted /
           / app data /  -70000:'text string'
         },
         / 2nd submod, A nested EAT from a secure element / {
           / submod_name / 30:'Secure Element EAT',
           / eat /         31:71( 18(
              / an embedded EAT / [ /...COSE_Sign1 bytes with payload.../ ]
                           ))
         }
         / 3rd submod, information about Linux Android / {
            / submod_name/ 30:'Linux Android',
            / seclevel /   10:1, / unrestricted /
            / custom - release / -80000:'8.0.0',
            / custom - version / -80001:'4.9.51+'
         }
      ]
}





Mandyam, et al.         Expires November 20, 2018              [Page 20]


Internet-Draft                     EAT                          May 2018


Authors' Addresses

   Giridhar Mandyam
   Qualcomm Technologies Inc.
   5775 Morehouse Drive
   San Diego, California
   USA

   Phone: +1 858 651 7200
   EMail: mandyam@qti.qualcomm.com


   Laurence Lundblade
   Qualcomm Technologies Inc.
   5775 Morehouse Drive
   San Diego, California
   USA

   Phone: +1 858 658 3584
   EMail: llundbla@qti.qualcomm.com


   Miguel Ballesteros
   Qualcomm Technologies Inc.
   5775 Morehouse Drive
   San Diego, California
   USA

   Phone: +1 858 651 4299
   EMail: mballest@qti.qualcomm.com


   Jeremy O'Donoghue
   Qualcomm Technologies Inc.
   279 Farnborough Road
   Farnborough  GU14 7LS
   United Kingdom

   Phone: +44 1252 363189
   EMail: jodonogh@qti.qualcomm.com











Mandyam, et al.         Expires November 20, 2018              [Page 21]


Html markup produced by rfcmarkup 1.127, available from https://tools.ietf.org/tools/rfcmarkup/