idnits 2.17.1 draft-ietf-rats-eat-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** There are 3 instances of too long lines in the document, the longest one being 3 characters in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (June 22, 2019) is 1763 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'Webauthn' is defined on line 933, but no explicit reference was found in the text ** Obsolete normative reference: RFC 7049 (Obsoleted by RFC 8949) ** Obsolete normative reference: RFC 8152 (Obsoleted by RFC 9052, RFC 9053) -- Possible downref: Non-RFC (?) normative reference: ref. 'WGS84' Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 RATS Working Group G. Mandyam 3 Internet-Draft Qualcomm Technologies Inc. 4 Intended status: Standards Track L. Lundblade 5 Expires: December 24, 2019 Security Theory LLC 6 M. Ballesteros 7 J. O'Donoghue 8 Qualcomm Technologies Inc. 9 June 22, 2019 11 The Entity Attestation Token (EAT) 12 draft-ietf-rats-eat-00 14 Abstract 16 An attestation format based on concise binary object representation 17 (CBOR) is proposed that is suitable for inclusion in a CBOR Web Token 18 (CWT), know as the Entity Attestation Token (EAT). The associated 19 data can be used by a relying party to assess the security state of a 20 remote device or module. 22 Contributing 24 TBD 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on December 24, 2019. 43 Copyright Notice 45 Copyright (c) 2019 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 61 1.1. Entity Overview . . . . . . . . . . . . . . . . . . . . . 4 62 1.2. Use of CBOR and COSE . . . . . . . . . . . . . . . . . . 5 63 1.3. EAT Operating Models . . . . . . . . . . . . . . . . . . 5 64 1.4. What is Not Standardized . . . . . . . . . . . . . . . . 6 65 1.4.1. Transmission Protocol . . . . . . . . . . . . . . . . 6 66 1.4.2. Signing Scheme . . . . . . . . . . . . . . . . . . . 7 67 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 68 3. The Claims . . . . . . . . . . . . . . . . . . . . . . . . . 8 69 3.1. Universal Entity ID (UEID) Claim . . . . . . . . . . . . 8 70 3.2. Origination (origination) Claims . . . . . . . . . . . . 11 71 3.3. OEM identification by IEEE OUI . . . . . . . . . . . . . 11 72 3.4. Security Level (seclevel) Claim . . . . . . . . . . . . . 12 73 3.5. Nonce (nonce) Claim . . . . . . . . . . . . . . . . . . . 13 74 3.6. Secure Boot and Debug Enable State Claims . . . . . . . . 13 75 3.6.1. Secure Boot Enabled (secbootenabled) Claim . . . . . 13 76 3.6.2. Debug Disabled (debugdisabled) Claim . . . . . . . . 13 77 3.6.3. Debug Disabled Since Boot (debugdisabledsincebboot) 78 Claim . . . . . . . . . . . . . . . . . . . . . . . . 13 79 3.6.4. Debug Permanent Disable (debugpermanentdisable) Claim 13 80 3.6.5. Debug Full Permanent Disable 81 (debugfullpermanentdisable) Claim . . . . . . . . . . 14 82 3.7. Location (loc) Claim . . . . . . . . . . . . . . . . . . 14 83 3.7.1. lat (latitude) claim . . . . . . . . . . . . . . . . 14 84 3.7.2. long (longitude) claim . . . . . . . . . . . . . . . 14 85 3.7.3. alt (altitude) claim . . . . . . . . . . . . . . . . 14 86 3.7.4. acc (accuracy) claim . . . . . . . . . . . . . . . . 14 87 3.7.5. altacc (altitude accuracy) claim . . . . . . . . . . 15 88 3.7.6. heading claim . . . . . . . . . . . . . . . . . . . . 15 89 3.7.7. speed claim . . . . . . . . . . . . . . . . . . . . . 15 90 3.8. ts (timestamp) claim . . . . . . . . . . . . . . . . . . 15 91 3.9. age claim . . . . . . . . . . . . . . . . . . . . . . . . 15 92 3.10. uptime claim . . . . . . . . . . . . . . . . . . . . . . 15 93 3.11. The submods Claim . . . . . . . . . . . . . . . . . . . . 16 94 3.11.1. The submod_name Claim . . . . . . . . . . . . . . . 16 95 3.11.2. Nested EATs, the eat Claim . . . . . . . . . . . . . 16 97 4. CBOR Interoperability . . . . . . . . . . . . . . . . . . . . 16 98 4.1. Integer Encoding (major type 0 and 1) . . . . . . . . . . 17 99 4.2. String Encoding (major type 2 and 3) . . . . . . . . . . 17 100 4.3. Map and Array Encoding (major type 4 and 5) . . . . . . . 17 101 4.4. Date and Time . . . . . . . . . . . . . . . . . . . . . . 17 102 4.5. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 17 103 4.6. Floating Point . . . . . . . . . . . . . . . . . . . . . 17 104 4.7. Other types . . . . . . . . . . . . . . . . . . . . . . . 17 105 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 106 5.1. Reuse of CBOR Web Token (CWT) Claims Registry . . . . . . 18 107 5.1.1. Claims Registered by This Document . . . . . . . . . 18 108 5.2. EAT CBOR Tag Registration . . . . . . . . . . . . . . . . 18 109 5.2.1. Tag Registered by This Document . . . . . . . . . . . 18 110 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 19 111 6.1. UEID Privacy Considerations . . . . . . . . . . . . . . . 19 112 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20 113 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 114 8.1. Normative References . . . . . . . . . . . . . . . . . . 20 115 8.2. Informative References . . . . . . . . . . . . . . . . . 21 116 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 22 117 A.1. Very Simple EAT . . . . . . . . . . . . . . . . . . . . . 22 118 A.2. Example with Submodules, Nesting and Security Levels . . 22 119 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 121 1. Introduction 123 Remote device attestation is fundamental service that allows a remote 124 device such as a mobile phone, an Internet-of-Things (IoT) device, or 125 other endpoint to prove itself to a relying party, a server or a 126 service. This allows the relying party to know some characteristics 127 about the device and decide whether it trusts the device. 129 Remote attestation is a fundamental service that can underlie other 130 protocols and services that need to know about the trustworthiness of 131 the device before proceeding. One good example is biometric 132 authentication where the biometric matching is done on the device. 133 The relying party needs to know that the device is one that is known 134 to do biometric matching correctly. Another example is content 135 protection where the relying party wants to know the device will 136 protect the data. This generalizes on to corporate enterprises that 137 might want to know that a device is trustworthy before allowing 138 corporate data to be accessed by it. 140 The notion of attestation here is large and may include, but is not 141 limited to the following: 143 o Proof of the make and model of the device hardware (HW) 144 o Proof of the make and model of the device processor, particularly 145 for security oriented chips 147 o Measurement of the software (SW) running on the device 149 o Configuration and state of the device 151 o Environmental characteristics of the device such as its GPS 152 location 154 The required data format should be general purpose and extensible so 155 that it can work across many use cases. This is why CBOR (see 156 [RFC7049]) was chosen as the format -- it already supports a rich set 157 of data types, and is both expressive and extensible. It translates 158 well to JSON for good interoperation with web technology. It is 159 compact and can work on very small IoT device. The format proposed 160 here is small enough that a limited version can be implemented in 161 pure hardware gates with no software at all. Moreover, the 162 attestation data is defined in the form of claims that is the same as 163 CBOR Web Token (CWT, see [RFC8392]). This is the motivation for 164 defining the Entity Attestation Token, i.e. EAT. 166 1.1. Entity Overview 168 An "entity" can be any device or device subassembly ("submodule") 169 that can generate its own attestation in the form of an EAT. The 170 attestation should be cryptographically verifiable by the EAT 171 consumer. An EAT at the device-level can be composed of several 172 submodule EAT's. It is assumed that any entity that can create an 173 EAT does so by means of a dedicated root-of-trust (RoT). 175 Modern devices such as a mobile phone have many different execution 176 environments operating with different security levels. For example 177 it is common for a mobile phone to have an "apps" environment that 178 runs an operating system (OS) that hosts a plethora of downloadable 179 apps. It may also have a TEE (Trusted Execution Environment) that is 180 distinct, isolated, and hosts security-oriented functionality like 181 biometric authentication. Additionally it may have an eSE (embedded 182 Secure Element) - a high security chip with defenses against HW 183 attacks that can serve as a RoT. This device attestation format 184 allows the attested data to be tagged at a security level from which 185 it originates. In general, any discrete execution environment that 186 has an identifiable security level can be considered an entity. 188 1.2. Use of CBOR and COSE 190 Fundamentally this attestation format is a verifiable data format. 191 It is a collection of data items that can be signed by an attestation 192 key, hashed, and/or encrypted. As per Section 7 of [RFC8392], the 193 verification method is in the CWT using the CBOR Object Signing and 194 Encryption (COSE) methodology (see [RFC8152]). 196 In addition, the reported attestation data could be determined within 197 the secure operating environment or written to it from an external 198 and presumably less trusted entity on the device. In either case, 199 the source of the reported data must be identifiable by the relying 200 party. 202 This attestation format is a single relatively simple signed message. 203 It is designed to be incorporated into many other protocols and many 204 other transports. It is also designed such that other SW and apps 205 can add their own data to the message such that it is also attested. 207 1.3. EAT Operating Models 209 At least the following three participants exist in all EAT operating 210 models. Some operating models have additional participants. 212 The Entity. This is the phone, the IoT device, the sensor, the sub- 213 assembly or such that the attestation provides information about. 215 The Manufacturer. The company that made the entity. This may be a 216 chip vendor, a circuit board module vendor or a vendor of finished 217 consumer products. 219 The Relying Party. The server, service or company that makes use of 220 the information in the EAT about the entity. 222 In all operating models, the manufacturer provisions some secret 223 attestation key material (AKM) into the entity during manufacturing. 224 This might be during the manufacturer of a chip at a fabrication 225 facility (fab) or during final assembly of a consumer product or any 226 time in between. This attestation key material is used for signing 227 EATs. 229 In all operating models, hardware and/or software on the entity 230 create an EAT of the format described in this document. The EAT is 231 always signed by the attestation key material provisioned by the 232 manufacturer. 234 In all operating models, the relying party must end up knowing that 235 the signature on the EAT is valid and consistent with data from 236 claims in the EAT. This can happen in many different ways. Here are 237 some examples. 239 o The EAT is transmitted to the relying party. The relying party 240 gets corresponding key material (e.g. a root certificate) from the 241 manufacturer. The relying party performs the verification. 243 o The EAT is transmitted to the relying party. The relying party 244 transmits the EAT to a verification service offered by the 245 manufacturer. The server returns the validated claims. 247 o The EAT is transmitted directly to a verification service, perhaps 248 operated by the manufacturer or perhaps by another party. It 249 verifies the EAT and makes the validated claims available to the 250 relying party. It may even modify the claims in some way and re- 251 sign the EAT (with a different signing key). 253 This standard supports all these operating models and does not prefer 254 one over the other. It is important to support this variety of 255 operating models to generally facilitate deployment and to allow for 256 some special scenarios. One special scenario has a validation 257 service that is monetized, most likely by the manufacturer. In 258 another, a privacy proxy service processes the EAT before it is 259 transmitted to the relying party. In yet another, symmetric key 260 material is used for signing. In this case the manufacturer should 261 perform the verification, because any release of the key material 262 would enable a participant other than the entity to create valid 263 signed EATs. 265 1.4. What is Not Standardized 267 1.4.1. Transmission Protocol 269 EATs may be transmitted by any protocol. For example, they might be 270 added in extension fields of other protocols, bundled into an HTTP 271 header, or just transmitted as files. This flexibility is 272 intentional to allow broader adoption. This flexibility is possible 273 because EAT's are self-secured with signing (and possibly 274 additionally with encryption and anti-replay). The transmission 275 protocol is not required to fulfill any additional security 276 requirements. 278 For certain devices, a direct connection may not exist between the 279 EAT-producing device and the Relying Party. In such cases, the EAT 280 should be protected against malicious access. The use of COSE allows 281 for signing and encryption of the EAT. Therefore even if the EAT is 282 conveyed through intermediaries between the device and Relying Party, 283 such intermediaries cannot easily modify the EAT payload or alter the 284 signature. 286 1.4.2. Signing Scheme 288 The term "signing scheme" is used to refer to the system that 289 includes end-end process of establishing signing attestation key 290 material in the entity, signing the EAT, and verifying it. This 291 might involve key IDs and X.509 certificate chains or something 292 similar but different. The term "signing algorithm" refers just to 293 the algorithm ID in the COSE signing structure. No particular 294 signing algorithm or signing scheme is required by this standard. 296 There are three main implementation issues driving this. First, 297 secure non-volatile storage space in the entity for the attestation 298 key material may be highly limited, perhaps to only a few hundred 299 bits, on some small IoT chips. Second, the factory cost of 300 provisioning key material in each chip or device may be high, with 301 even millisecond delays adding to the cost of a chip. Third, 302 privacy-preserving signing schemes like ECDAA (Elliptic Curve Direct 303 Anonymous Attestation) are complex and not suitable for all use 304 cases. 306 Eventually some form of standardization of the signing scheme may be 307 required. This might come in the form of another standard that adds 308 to this document, or when there is clear convergence on a small 309 number of signing schemes this standard can be updated. 311 2. Terminology 313 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 314 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 315 "OPTIONAL" in this document are to be interpreted as described in BCP 316 14 [RFC2119] [RFC8174] when, and only when, they appear in all 317 capitals, as shown here. 319 This document reuses terminology from JWT [RFC7519], COSE [RFC8152], 320 and CWT [RFC8392]. 322 StringOrURI. The "StringOrURI" term in this specification has the 323 same meaning and processing rules as the JWT "StringOrURI" term 324 defined in Section 2 of [RFC7519], except that it is represented 325 as a CBOR text string instead of a JSON text string. 327 NumericDate. The "NumericDate" term in this specification has the 328 same meaning and processing rules as the JWT "NumericDate" term 329 defined in Section 2 of [RFC7519], except that it is represented 330 as a CBOR numeric date (from Section 2.4.1 of [RFC7049]) instead 331 of a JSON number. The encoding is modified so that the leading 332 tag 1 (epoch-based date/time) MUST be omitted. 334 Claim Name. The human-readable name used to identify a claim. 336 Claim Key. The CBOR map key used to identify a claim. 338 Claim Value. The CBOR map value representing the value of the claim. 340 CWT Claims Set. The CBOR map that contains the claims conveyed by 341 the CWT. 343 FloatOrNumber. The "FloatOrNumber" term in this specification is the 344 type of a claim that is either a CBOR positive integer, negative 345 integer or floating point number. 347 Attestation Key Material (AKM). The key material used to sign the 348 EAT token. If it is done symmetrically with HMAC, then this is a 349 simple symmetric key. If it is done with ECC, such as an IEEE 350 DevID [IDevID], then this is the private part of the EC key pair. 351 If ECDAA is used, (e.g., as used by Enhanced Privacy ID, i.e. 352 EPID) then it is the key material needed for ECDAA. 354 3. The Claims 356 3.1. Universal Entity ID (UEID) Claim 358 UEID's identify individual manufactured entities / devices such as a 359 mobile phone, a water meter, a Bluetooth speaker or a networked 360 security camera. It may identify the entire device or a submodule or 361 subsystem. It does not identify types, models or classes of devices. 362 It is akin to a serial number, though it does not have to be 363 sequential. 365 It is identified by Claim Key X (X is TBD). 367 UEID's must be universally and globally unique across manufacturers 368 and countries. UEIDs must also be unique across protocols and 369 systems, as tokens are intended to be embedded in many different 370 protocols and systems. No two products anywhere, even in completely 371 different industries made by two different manufacturers in two 372 different countries. should have the same UEID (if they are not 373 global and universal in this way then relying parties receiving them 374 will have to track other characteristics of the device to keep 375 devices distinct between manufacturers). 377 The UEID should be permanent. It should never change for a given 378 device / entity. In addition, it should not be reprogrammable. 380 UEID's are binary byte-strings (resulting in a smaller size than text 381 strings). When handled in text-based protocols, they should be 382 base-64 encoded. 384 UEID's are variable length with a maximum size of 33 bytes (1 type 385 byte and 256 bits). A receivers of a token with UEIDs may reject the 386 token if a UEID is larger than 33 bytes. 388 UEID's are not designed for direct use by humans (e.g., printing on 389 the case of a device), so no textual representation is defined. 391 A UEID is a byte string. From the consumer's view (the rely party) 392 it is opaque with no bytes having any special meaning. 394 When the entity constructs the UEID, the first byte is a type and the 395 following bytes the ID for that type. Several types are allowed to 396 accommodate different industries and different manufacturing 397 processes and to give options to avoid paying fees for certain types 398 of manufacturer registrations. 400 +------+--------+---------------------------------------------------+ 401 | Type | Type | Specification | 402 | Byte | Name | | 403 +------+--------+---------------------------------------------------+ 404 | 0x01 | GUID | This is a 128 to 256 bit random number generated | 405 | | | once and stored in the device. The GUID may be | 406 | | | constructed from various identifiers on the | 407 | | | device using a hash function or it may be just | 408 | | | the raw random number. | 409 | 0x02 | IEEE | This makes use of the IEEE company identification | 410 | | EUI | registry. An EUI is made up of an OUI and OUI-36 | 411 | | | or a CID, different registered company | 412 | | | identifiers, and some unique per-device | 413 | | | identifier. EUIs are often the same as or similar | 414 | | | to MAC addresses. (Note that while devices with | 415 | | | multiple network interfaces may have multiple MAC | 416 | | | addresses, there is only one UEID for a device) | 417 | | | TODO: normative references to IEEE. | 418 | 0x03 | IMEI | This is a 14-digit identifier consisting of an 8 | 419 | | | digit Type Allocation Code and a six digit serial | 420 | | | number allocated by the manufacturer, which SHALL | 421 | | | be encoded as a binary integer over 48 bits. The | 422 | | | IMEI value encoded SHALL NOT include Luhn | 423 | | | checksum or SVN information. | 424 | 0x04 | EUI-48 | This is a 48-bit identifier formed by | 425 | | | concatenating the 24-bit OUI with a 24-bit | 426 | | | identifier assigned by the organisation that | 427 | | | purchased the OUI. | 428 | 0x05 | EUI-60 | This is a 60-bit identifier formed by | 429 | | | concatenating the 24-bit OUI with a 36-bit | 430 | | | identifier assigned by the organisation that | 431 | | | purchased the OUI. | 432 | 0x06 | EUI-64 | This is a 64-bit identifier formed by | 433 | | | concatenating the 24-bit OUI with a 40-bit | 434 | | | identifier assigned by the organisation that | 435 | | | purchased the OUI. | 436 +------+--------+---------------------------------------------------+ 438 Table 1: UEID Composition Types 440 The consumer (the Relying Party) of a UEID should treat a UEID as a 441 completely opaque string of bytes and not make any use of its 442 internal structure. For example they should not use the OUI part of 443 a type 0x02 UEID to identify the manufacturer of the device. Instead 444 they should use the OUI claim that is defined elsewhere. The reasons 445 for this are: 447 o UEIDs types may vary freely from one manufacturer to the next. 449 o New types of UEIDs may be created. For example a type 0x04 UEID 450 may be created based on some other manufacturer registration 451 scheme. 453 o Device manufacturers are allowed to change from one type of UEID 454 to another anytime they want. For example they may find they can 455 optimize their manufacturing by switching from type 0x01 to type 456 0x02 or vice versa. The main requirement on the manufacturer is 457 that UEIDs be universally unique. 459 3.2. Origination (origination) Claims 461 This claim describes the parts of the device or entity that are 462 creating the EAT. Often it will be tied back to the device or chip 463 manufacturer. The following table gives some examples: 465 +-------------------+-----------------------------------------------+ 466 | Name | Description | 467 +-------------------+-----------------------------------------------+ 468 | Acme-TEE | The EATs are generated in the TEE authored | 469 | | and configured by "Acme" | 470 | Acme-TPM | The EATs are generated in a TPM manufactured | 471 | | by "Acme" | 472 | Acme-Linux-Kernel | The EATs are generated in a Linux kernel | 473 | | configured and shipped by "Acme" | 474 | Acme-TA | The EATs are generated in a Trusted | 475 | | Application (TA) authored by "Acme" | 476 +-------------------+-----------------------------------------------+ 478 The claim is represented by Claim Key X+1. It is type StringOrURI. 480 TODO: consider a more structure approach where the name and the URI 481 and other are in separate fields. 483 TODO: This needs refinement. It is somewhat parallel to issuer claim 484 in CWT in that it describes the authority that created the token. 486 3.3. OEM identification by IEEE OUI 488 This claim identifies a device OEM by the IEEE OUI. Reference TBD. 489 It is a byte string representing the OUI in binary form in network 490 byte order (TODO: confirm details). 492 Companies that have more than one IEEE OUI registered with IEEE 493 should pick one and prefer that for all their devices. 495 Note that the OUI is in common use as a part of MAC Address. This 496 claim is only the first bits of the MAC address that identify the 497 manufacturer. The IEEE maintains a registry for these in which many 498 companies participate. This claim is represented by Claim Key TBD. 500 3.4. Security Level (seclevel) Claim 502 EATs have a claim that roughly characterizes the device / entities 503 ability to defend against attacks aimed at capturing the signing key, 504 forging claims and at forging EATs. This is done by roughly defining 505 four security levels as described below. This is similar to the 506 security levels defined in the Metadata Service definied by the Fast 507 Identity Online (FIDO) Alliance (TODO: reference). 509 These claims describe security environment and countermeasures 510 available on the end-entity / client device where the attestation key 511 reside and the claims originate. 513 This claim is identified by Claim Key X+2. The value is an integer 514 between 1 and 4 as defined below. 516 1 - Unrestricted There is some expectation that implementor will 517 protect the attestation signing keys at this level. Otherwise the 518 EAT provides no meaningful security assurances. 520 2- Restricted Entities at this level should not be general-purpose 521 operating environments that host features such as app download 522 systems, web browsers and complex productivity applications. It 523 is akin to the Secure Restricted level (see below) without the 524 security orientation. Examples include a WiFi subsystem, an IoT 525 camera, or sensor device. 527 3 - Secure Restricted Entities at this level must meet the critera 528 defined by FIDO Allowed Restricted Operating Environments (TODO: 529 reference). Examples include TEE's and schemes using 530 virtualization-based security. Like the FIDO security goal, 531 security at this level is aimed at defending well against large- 532 scale network / remote attacks against the device. 534 4 - Hardware Entities at this level must include substantial defense 535 against physical or electrical attacks against the device itself. 536 It is assumed any potential attacker has captured the device and 537 can disassemble it. Example include TPMs and Secure Elements. 539 This claim is not intended as a replacement for a proper end-device 540 security certification schemes such as those based on FIPS (TODO: 541 reference) or those based on Common Criteria (TODO: reference). The 542 claim made here is solely a self-claim made by the Entity Originator. 544 3.5. Nonce (nonce) Claim 546 The "nonce" (Nonce) claim represents a random value that can be used 547 to avoid replay attacks. This would be ideally generated by the CWT 548 consumer. This value is intended to be a CWT companion claim to the 549 existing JWT claim **_IANAJWT_ (TODO: fix this reference). The nonce 550 claim is identified by Claim Key X+3. 552 3.6. Secure Boot and Debug Enable State Claims 554 3.6.1. Secure Boot Enabled (secbootenabled) Claim 556 The "secbootenabled" (Secure Boot Enabled) claim represents a boolean 557 value that indicates whether secure boot is enabled either for an 558 entire device or an individual submodule. If it appears at the 559 device level, then this means that secure boot is enabled for all 560 submodules. Secure boot enablement allows a secure boot loader to 561 authenticate software running either in a device or a submodule prior 562 allowing execution. This claim is identified by Claim Key X+4. 564 3.6.2. Debug Disabled (debugdisabled) Claim 566 The "debugdisabled" (Debug Disabled) claim represents a boolean value 567 that indicates whether debug capabilities are disabled for an entity 568 (i.e. value of 'true'). Debug disablement is considered a 569 prerequisite before an entity is considered operational. This claim 570 is identified by Claim Key X+5. 572 3.6.3. Debug Disabled Since Boot (debugdisabledsincebboot) Claim 574 The "debugdisabledsinceboot" (Debug Disabled Since Boot) claim 575 represents a boolean value that indicates whether debug capabilities 576 for the entity were not disabled in any way since boot (i.e. value of 577 'true'). This claim is identified by Claim Key X+6. 579 3.6.4. Debug Permanent Disable (debugpermanentdisable) Claim 581 The "debugpermanentdisable" (Debug Permanent Disable) claim 582 represents a boolean value that indicates whether debug capabilities 583 for the entity are permanently disabled (i.e. value of 'true'). This 584 value can be set to 'true' also if only the manufacturer is allowed 585 to enabled debug, but the end user is not. This claim is identified 586 by Claim Key X+7. 588 3.6.5. Debug Full Permanent Disable (debugfullpermanentdisable) Claim 590 The "debugfullpermanentdisable" (Debug Full Permanent Disable) claim 591 represents a boolean value that indicates whether debug capabilities 592 for the entity are permanently disabled (i.e. value of 'true'). This 593 value can only be set to 'true' if no party can enable debug 594 capabilities for the entity. Often this is implemented by blowing a 595 fuse on a chip as fuses cannot be restored once blown. This claim is 596 identified by Claim Key X+8. 598 3.7. Location (loc) Claim 600 The "loc" (location) claim is a CBOR-formatted object that describes 601 the location of the device entity from which the attestation 602 originates. It is identified by Claim Key X+10. It is comprised of 603 an array of additional subclaims that represent the actual location 604 coordinates (latitude, longitude and altitude). The location 605 coordinate claims are consistent with the WGS84 coordinate system 606 [WGS84]. In addition, a subclaim providing the estimated accuracy of 607 the location measurement is defined. 609 3.7.1. lat (latitude) claim 611 The "lat" (latitude) claim contains the value of the device location 612 corresponding to its latitude coordinate. It is of data type 613 FloatOrNumber and identified by Claim Key X+11. 615 3.7.2. long (longitude) claim 617 The "long" (longitude) claim contains the value of the device 618 location corresponding to its longitude coordinate. It is of data 619 type FloatOrNumber and identified by Claim Key X+12. 621 3.7.3. alt (altitude) claim 623 The "alt" (altitude) claim contains the value of the device location 624 corresponding to its altitude coordinate (if available). It is of 625 data type FloatOrNumber and identified by Claim Key X+13. 627 3.7.4. acc (accuracy) claim 629 The "acc" (accuracy) claim contains a value that describes the 630 location accuracy. It is non-negative and expressed in meters. It 631 is of data type FloatOrNumber and identified by Claim Key X+14. 633 3.7.5. altacc (altitude accuracy) claim 635 The "altacc" (altitude accuracy) claim contains a value that 636 describes the altitude accuracy. It is non-negative and expressed in 637 meters. It is of data type FloatOrNumber and identified by Claim Key 638 X+15. 640 3.7.6. heading claim 642 The "heading" claim contains a value that describes direction of 643 motion for the entity. Its value is specified in degrees, between 0 644 and 360. It is of data type FloatOrNumber and identified by Claim 645 Key X+16. 647 3.7.7. speed claim 649 The "speed" claim contains a value that describes the velocity of the 650 entity in the horizontal direction. Its value is specified in 651 meters/second and must be non-negative. It is of data type 652 FloatOrNumber and identified by Claim Key X+17. 654 3.8. ts (timestamp) claim 656 The "ts" (timestamp) claim contains a timestamp derived using the 657 same time reference as is used to generate an "iat" claim (see 658 Section 3.1.6 of [RFC8392]). It is of the same type as "iat" 659 (integer or floating-point), and is identified by Claim Key X+18. It 660 is meant to designate the time at which a measurement was taken, when 661 a location was obtained, or when a token was actually transmitted. 662 The timestamp would be included as a subclaim under the "submod" or 663 "loc" claims (in addition to the existing respective subclaims), or 664 at the device level. 666 3.9. age claim 668 The "age" claim contains a value that represents the number of 669 seconds that have elapsed since the token was created, measurement 670 was made, or location was obtained. Typical attestable values are 671 sent as soon as they are obtained. However in the case that such a 672 value is buffered and sent at a later time and a sufficiently 673 accurate time reference is unavailable for creation of a timestamp, 674 then the age claim is provided. It is identified by Claim Key X+19. 676 3.10. uptime claim 678 The "uptime" claim contains a value that represents the number of 679 seconds that have elapsed since the entity or submod was last booted. 680 It is identified by Claim Key X+20. 682 3.11. The submods Claim 684 Some devices are complex, having many subsystems or submodules. A 685 mobile phone is a good example. It may have several connectivity 686 submodules for communications (e.g., WiFi and cellular). It may have 687 sub systems for low-power audio and video playback. It may have one 688 or more security-oriented subsystems like a TEE or a Secure Element. 690 The claims for each these can be grouped together in a submodule. 692 Specifically, the "submods" claim is an array. Each item in the 693 array is a CBOR map containing all the claims for a particular 694 submodule. It is identified by Claim Key X+22. 696 The security level of the submod is assumed to be at the same level 697 as the main entity unless there is a security level claim in that 698 submodule indicating otherwise. The security level of a submodule 699 can never be higher (more secure) than the security level of the EAT 700 it is a part of. 702 3.11.1. The submod_name Claim 704 Each submodule should have a submod_name claim that is descriptive 705 name. This name should be the CBOR txt type. 707 3.11.2. Nested EATs, the eat Claim 709 It is allowed for one EAT to be embedded in another. This is for 710 complex devices that have more than one subsystem capable of 711 generating an EAT. Typically one will be the device-wide EAT that is 712 low to medium security and another from a Secure Element or similar 713 that is high security. 715 The contents of the "eat" claim must be a fully signed, optionally 716 encrypted, EAT token. It is identified by Claim Key X+23. 718 4. CBOR Interoperability 720 EAT is a one-way protocol. It only defines a single message that 721 goes from the entity to the server. The entity implementation will 722 often be in a contained environment with little RAM and the server 723 will usually not be. The following requirements for interoperability 724 take that into account. The entity can generally use whatever 725 encoding it wants. The server is required to support just about 726 every encoding. 728 Canonical CBOR encoding is explicitly NOT required as it would place 729 an unnecessary burden on the entity implementation. 731 4.1. Integer Encoding (major type 0 and 1) 733 The entity may use any integer encoding allowed by CBOR. The server 734 MUST accept all integer encodings allowed by CBOR. 736 4.2. String Encoding (major type 2 and 3) 738 The entity can use any string encoding allowed by CBOR including 739 indefinite lengths. It may also encode the lengths of strings in any 740 way allowed by CBOR. The server must accept all string encodings. 742 Major type 2, bstr, SHOULD be have tag 21, 22 or 23 to indicate 743 conversion to base64 or such when converting to JSON. 745 4.3. Map and Array Encoding (major type 4 and 5) 747 The entity can use any array or map encoding allowed by CBOR 748 including indefinite lengths. Sorting of map keys is not required. 749 Duplicate map keys are not allowed. The server must accept all array 750 and map encodings. The server may reject maps with duplicate map 751 keys. 753 4.4. Date and Time 755 The entity should send dates as tag 1 encoded as 64-bit or 32-bit 756 integers. The entity may not send floating point dates. The server 757 must support tag 1 epoch based dates encoded as 64-bit or 32-bit 758 integers. 760 The entity may send tag 0 dates, however tag 1 is preferred. The 761 server must support tag 0 UTC dates. 763 4.5. URIs 765 URIs should be encoded as text strings and marked with tag 32. 767 4.6. Floating Point 769 Encoding data in floating point is to be used only if necessary. 770 Location coordinates are always in floating point. The server must 771 support decoding of all types of floating point. 773 4.7. Other types 775 Use of Other types like bignums, regular expressions and so SHOULD 776 NOT be used. The server MAY support them, but is not required to. 777 Use of these tags is 779 5. IANA Considerations 781 5.1. Reuse of CBOR Web Token (CWT) Claims Registry 783 Claims defined for EAT are compatible with those of CWT so the CWT 784 Claims Registry is re used. New new IANA registry is created. All 785 EAT claims should be registered in the CWT Claims Registry. 787 5.1.1. Claims Registered by This Document 789 o Claim Name: UEID 791 o Claim Description: The Universal Entity ID 793 o JWT Claim Name: N/A 795 o Claim Key: X 797 o Claim Value Type(s): byte string 799 o Change Controller: IESG 801 o Specification Document(s): *this document* 803 TODO: add the rest of the claims in here 805 5.2. EAT CBOR Tag Registration 807 How an EAT consumer determines whether received CBOR-formatted data 808 actually represents a valid EAT is application-dependent, much like a 809 CWT. For instance, a specific MIME type associated with the EAT such 810 as "application/eat" could be sufficient for identification of the 811 EAT. Note however that EAT's can include other EAT's (e.g. a device 812 EAT comprised of several submodule EAT's). In this case, a CBOR tag 813 dedicated to the EAT will be required at least for the submodule 814 EAT's and the tag must be a valid CBOR tag. In other words - the EAT 815 CBOR tag can optionally prefix a device-level EAT, but a EAT CBOR tag 816 must always prefix a submodule EAT. The proposed EAT CBOR tag is 71. 818 5.2.1. Tag Registered by This Document 820 o CBOR Tag: 71 822 o Data Item: Entity Attestation Token (EAT) 824 o Semantics: Entity Attestation Token (CWT), as defined in 825 *this_doc* 827 o Reference: *this_doc* 829 o Point of Contact: Giridhar Mandyam, mandyam@qti.qualcomm.com 831 6. Privacy Considerations 833 Certain EAT claims can be used to track the owner of an entity and 834 therefore implementations should consider providing privacy- 835 preserving options dependent on the intended usage of the EAT. 836 Examples would include suppression of location claims for EAT's 837 provided to unauthenticated consumers. 839 6.1. UEID Privacy Considerations 841 A UEID is usually not privacy preserving. Any set of relying parties 842 that receives tokens that happen to be from a single device will be 843 able to know the tokens are all from the same device and be able to 844 track the device. Thus, in many usage situations ueid violates 845 governmental privacy regulation. In other usage situations UEID will 846 not be allowed for certain products like browsers that give privacy 847 for the end user. it will often be the case that tokens will not 848 have a UEID for these reasons. 850 There are several strategies that can be used to still be able to put 851 UEID's in tokens: 853 o The device obtains explicit permission from the user of the device 854 to use the UEID. This may be through a prompt. It may also be 855 through a license agreement. For example, agreements for some 856 online banking and brokerage services might already cover use of a 857 UEID. 859 o The UEID is used only in a particular context or particular use 860 case. It is used only by one relying party. 862 o The device authenticates the relying party and generates a derived 863 UEID just for that particular relying party. For example, the 864 relying party could prove their identity cryptographically to the 865 device, then the device generates a UEID just for that relying 866 party by hashing a proofed relying party ID with the main device 867 UEID. 869 Note that some of these privacy preservation strategies result in 870 multiple UEIDs per device. Each UEID is used in a different context, 871 use case or system on the device. However, from the view of the 872 relying party, there is just one UEID and it is still globally 873 universal across manufacturers. 875 7. Security Considerations 877 TODO: Perhaps this can be the same as CWT / COSE, but not sure yet 878 because it involves so much entity / device security that those do 879 not. 881 8. References 883 8.1. Normative References 885 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 886 Requirement Levels", BCP 14, RFC 2119, 887 DOI 10.17487/RFC2119, March 1997, 888 . 890 [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object 891 Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, 892 October 2013, . 894 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 895 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 896 . 898 [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", 899 RFC 8152, DOI 10.17487/RFC8152, July 2017, 900 . 902 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 903 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 904 May 2017, . 906 [RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, 907 "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, 908 May 2018, . 910 [TIME_T] The Open Group Base Specifications, "Vol. 1: Base 911 Definitions, Issue 7", Section 4.15 'Seconds Since the 912 Epoch', IEEE Std 1003.1, 2013 Edition, 2013, 913 . 916 [WGS84] National Imagery and Mapping Agency, "National Imagery and 917 Mapping Agency Technical Report 8350.2, Third Edition", 918 2000, . 921 8.2. Informative References 923 [ASN.1] International Telecommunication Union, "Information 924 Technology -- ASN.1 encoding rules: Specification of Basic 925 Encoding Rules (BER), Canonical Encoding Rules (CER) and 926 Distinguished Encoding Rules (DER)", ITU-T Recommendation 927 X.690, 1994. 929 [IDevID] "IEEE Standard, "IEEE 802.1AR Secure Device Identifier"", 930 December 2009, . 933 [Webauthn] 934 Worldwide Web Consortium, "Web Authentication: A Web API 935 for accessing scoped credentials", 2016. 937 Appendix A. Examples 939 A.1. Very Simple EAT 941 This is shown in CBOR diagnostic form. Only the payload signed by 942 COSE is shown. 944 { 945 / nonce / 11:h'948f8860d13a463e8e', 946 / UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f', 947 / secbootenabled / 13:true, 948 / debugpermanentdisable / 15:true, 949 / ts / 21:1526542894, 950 } 952 A.2. Example with Submodules, Nesting and Security Levels 954 { 955 / nonce / 11:h'948f8860d13a463e8e', 956 / UEID / 8:h'0198f50a4ff6c05861c8860d13a638ea4fe2f', 957 / secbootenabled / 13:true, 958 / debugpermanentdisable / 15:true, 959 / ts / 21:1526542894, 960 / seclevel / 10:3, / secure restriced OS / 962 / submods / 30: 963 [ 964 / 1st submod, an Android Application / { 965 / submod_name / 30:'Android App "Foo"', 966 / seclevel / 10:1, / unrestricted / 967 / app data / -70000:'text string' 968 }, 969 / 2nd submod, A nested EAT from a secure element / { 970 / submod_name / 30:'Secure Element EAT', 971 / eat / 31:71( 18( 972 / an embedded EAT / [ /...COSE_Sign1 bytes with payload.../ ] 973 )) 974 } 975 / 3rd submod, information about Linux Android / { 976 / submod_name/ 30:'Linux Android', 977 / seclevel / 10:1, / unrestricted / 978 / custom - release / -80000:'8.0.0', 979 / custom - version / -80001:'4.9.51+' 980 } 981 ] 982 } 983 Authors' Addresses 985 Giridhar Mandyam 986 Qualcomm Technologies Inc. 987 5775 Morehouse Drive 988 San Diego, California 989 USA 991 Phone: +1 858 651 7200 992 EMail: mandyam@qti.qualcomm.com 994 Laurence Lundblade 995 Security Theory LLC 997 EMail: lgl@island-resort.com 999 Miguel Ballesteros 1000 Qualcomm Technologies Inc. 1001 5775 Morehouse Drive 1002 San Diego, California 1003 USA 1005 Phone: +1 858 651 4299 1006 EMail: mballest@qti.qualcomm.com 1008 Jeremy O'Donoghue 1009 Qualcomm Technologies Inc. 1010 279 Farnborough Road 1011 Farnborough GU14 7LS 1012 United Kingdom 1014 Phone: +44 1252 363189 1015 EMail: jodonogh@qti.qualcomm.com