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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Schaad 3 Internet-Draft August Cellars 4 Intended status: Informational June 19, 2015 5 Expires: December 21, 2015 7 CBOR Encoded Message Syntax 8 draft-schaad-cose-msg-01 10 Abstract 12 Concise Binary Object Representation (CBOR) is data format designed 13 for small code size and small message size. There is a need for the 14 ability to have the basic security services defined for this data 15 format. This document specifies how to do signatures, message 16 authentication codes and encryption using this data format. 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at http://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on December 21, 2015. 35 Copyright Notice 37 Copyright (c) 2015 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 53 1.1. Design changes from JOSE . . . . . . . . . . . . . . . . 3 54 1.2. Requirements Terminology . . . . . . . . . . . . . . . . 4 55 1.3. CBOR Grammar . . . . . . . . . . . . . . . . . . . . . . 4 56 1.4. CBOR Related Terminology . . . . . . . . . . . . . . . . 5 57 2. The COSE_MSG structure . . . . . . . . . . . . . . . . . . . 5 58 3. Header Parameters . . . . . . . . . . . . . . . . . . . . . . 8 59 3.1. COSE Headers . . . . . . . . . . . . . . . . . . . . . . 9 60 4. Signing Structure . . . . . . . . . . . . . . . . . . . . . . 12 61 5. Encryption object . . . . . . . . . . . . . . . . . . . . . . 15 62 5.1. Key Management Methods . . . . . . . . . . . . . . . . . 16 63 5.1.1. Direct Encryption . . . . . . . . . . . . . . . . . . 17 64 5.1.2. Key Wrapping . . . . . . . . . . . . . . . . . . . . 17 65 5.1.3. Key Encryption . . . . . . . . . . . . . . . . . . . 18 66 5.1.4. Direct Key Agreement . . . . . . . . . . . . . . . . 18 67 5.1.5. Key Agreement with Key Wrapping . . . . . . . . . . . 18 68 5.2. Encryption Algorithm for AEAD algorithms . . . . . . . . 19 69 5.3. Encryption algorithm for AE algorithms . . . . . . . . . 20 70 6. MAC objects . . . . . . . . . . . . . . . . . . . . . . . . . 20 71 7. Key Structure . . . . . . . . . . . . . . . . . . . . . . . . 22 72 8. CBOR Encoder Restrictions . . . . . . . . . . . . . . . . . . 23 73 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 74 9.1. CBOR Tag assignment . . . . . . . . . . . . . . . . . . . 24 75 9.2. COSE Object Labels Registry . . . . . . . . . . . . . . . 24 76 9.3. COSE Header Label Table . . . . . . . . . . . . . . . . . 24 77 9.4. COSE Header Algorithm Label Table . . . . . . . . . . . . 25 78 9.5. COSE Algorithm Registry . . . . . . . . . . . . . . . . . 26 79 9.6. COSE Key Map Registry . . . . . . . . . . . . . . . . . . 26 80 9.7. COSE Key Parameter Registry . . . . . . . . . . . . . . . 27 81 9.8. Media Type Registration . . . . . . . . . . . . . . . . . 28 82 9.8.1. COSE Security Message . . . . . . . . . . . . . . . . 28 83 9.8.2. COSE Key media type . . . . . . . . . . . . . . . . . 30 84 10. Security Considerations . . . . . . . . . . . . . . . . . . . 32 85 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 32 86 11.1. Normative References . . . . . . . . . . . . . . . . . . 32 87 11.2. Informative References . . . . . . . . . . . . . . . . . 32 88 Appendix A. AEAD and AE algorithms . . . . . . . . . . . . . . . 33 89 Appendix B. Three Levels of Recipient Information . . . . . . . 34 90 Appendix C. Examples . . . . . . . . . . . . . . . . . . . . . . 36 91 C.1. Direct MAC . . . . . . . . . . . . . . . . . . . . . . . 36 92 C.2. Wrapped MAC . . . . . . . . . . . . . . . . . . . . . . . 37 93 C.3. Multi-recipient MAC message . . . . . . . . . . . . . . . 38 94 C.4. Direct ECDH . . . . . . . . . . . . . . . . . . . . . . . 39 95 C.5. Single Signature . . . . . . . . . . . . . . . . . . . . 40 96 C.6. Multiple Signers . . . . . . . . . . . . . . . . . . . . 41 97 Appendix D. COSE Header Algorithm Label Table . . . . . . . . . 42 98 Appendix E. COSE Algorithm Name Values . . . . . . . . . . . . . 43 99 Appendix F. COSE General Values . . . . . . . . . . . . . . . . 45 100 Appendix G. COSE Key Map Labels . . . . . . . . . . . . . . . . 45 101 Appendix H. COSE Key Parameter Labels . . . . . . . . . . . . . 46 102 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 48 104 1. Introduction 106 There has been an increased focus on the small, constrained devices 107 that make up the Internet of Things (IOT). One of the standards that 108 has come of of this process is the Concise Binary Object 109 Representation (CBOR). This standard extends the data model of the 110 JavaScript Object Notation (JSON) by allowing for binary data among 111 other changes. CBOR is being adopted by several of the IETF working 112 groups dealing with the IOT world to do their encoding of data 113 structures. CBOR was designed specifically to be both small in terms 114 of messages transport and implementation size. A need exists to 115 provide basic message security services for IOT and using CBOR as the 116 message encoding format makes sense. 118 The JOSE working group produced a set of documents 119 [RFC7515][RFC7516][RFC7517][RFC7518] that defined how to perform 120 encryption, signatures and message authentication (MAC) operations 121 for JavaScript Object Notation (JSON) documents and then to encode 122 the results using the JSON format [RFC7159]. This document does the 123 same work for use with the Concise Binary Object Representation 124 (CBOR) [RFC7049] document format. While there is a strong attempt to 125 keep the flavor of the original JOSE documents, two considerations 126 are taken into account: 128 o CBOR has capabilities that are not present in JSON and should be 129 used. One example of this is the fact that CBOR has a method of 130 encoding binary directly without first converting it into a base64 131 encoded string. 133 o The author did not always agree with some of the decisions made by 134 the JOSE working group. Many of these decisions have been re- 135 examined, and where it seems to the author to be superior or 136 simpler, replaced. 138 1.1. Design changes from JOSE 140 o Define a top level message structure so that encrypted, signed and 141 MAC-ed messages can easily identified and still have a consistent 142 view. 144 o Signed messages separate the concept of protected and unprotected 145 attributes that are for the content and the signature. 147 o Key management has been made to be more uniform. All key 148 management techniques are represented as a recipient rather than 149 only have some of them be so. 151 o MAC messages are separated from signed messages. 153 o MAC messages have the ability to do key management on the MAC 154 authentication key. 156 o Use binary encodings for binary data rather than base64url 157 encodings. 159 o Combine the authentication tag for encryption algorithms with the 160 ciphertext. 162 o Remove the flattened mode of encoding. Forcing the use of an 163 array of recipients at all times forces the message size to be two 164 bytes larger, but one gets a corresponding decrease in the 165 implementation size that should compensate for this. [CREF1] 167 1.2. Requirements Terminology 169 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 170 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 171 "OPTIONAL" in this document are to be interpreted as described in 172 [RFC2119]. 174 When the words appear in lower case, their natural language meaning 175 is used. 177 1.3. CBOR Grammar 179 There currently is no standard CBOR grammar available for use by 180 specifications. In this document, we use the grammar defined in the 181 CBOR data definition language (CDDL) 182 [I-D.greevenbosch-appsawg-cbor-cddl]. 184 CDDL productions that together define the grammar are interspersed in 185 the document like this: 187 start = COSE_MSG 189 Note that, fromthe XML version of the present document, the collected 190 CDDL can be extracted via the following XPath expression: 192 //artwork[@type='CDDL']/text() 193 NOTE: At some point we need to make some decisions about how we are 194 using CDDL in this document. Since this draft has not been moving 195 forward at a great rate, changing all references on it to 196 informational is a good idea. On the other hand, having some type of 197 syntax that can be examined by a machine to do syntax checking is a 198 big win. The build system for this draft is currently using the 199 latest version of CDDL to check that the syntax of the examples is 200 correct. Doing this has found problems in both the syntax checker, 201 the syntax and the examples. 203 1.4. CBOR Related Terminology 205 In JSON, maps are called objects and only have one kind of map key: a 206 string. In COSE, we use both strings and integers (both positive and 207 negative integers) as map keys, as well as data items to identify 208 specific choices. The (positive and negative) integers are used for 209 compactness of encoding and easy comparison. Since the work "key" is 210 mainly used in its other meaning, as a cryptographic key, we use the 211 term "label" for this usage of either an integer or a string to 212 identify map keys and choice data items. 214 label = int / tstr 216 2. The COSE_MSG structure 218 The COSE_MSG structure is a top level CBOR object which corresponds 219 to the DataContent type in the Cryptographic Message Syntax 220 (CMS)[RFC5652]. This structure allows for a top level message to be 221 sent which could be any of the different security services. The 222 security service is identified within the message. 224 The COSE_Tagged_MSG CBOR type takes the COSE_MSG and prepends a CBOR 225 tag of TBD1 to the encoding of COSE_MSG. By having both a tagged and 226 untagged version of the COSE_MSG structure, it becomes easy to either 227 use COSE_MSG as a top level object or embedded in another object. 228 The tagged version allows for a method of placing the COSE_MSG 229 structure into a choice, using a consistent tag value to determine 230 that this is a COSE object. 232 The existence of the COSE_MSG and COSE_Tagged_MSG CBOR data types are 233 not intended to prevent protocols from using the individual security 234 primitives directly. Where only a single service is required, that 235 structure can be used directly. 237 Each of the top-level security objects use a CBOR map as the base 238 structure. Items in the map at the top level are identified by a 239 label. This document defines a number of labels in the IANA "COSE 240 Object Labels Registry" (defined in Section 9.2). 242 The set of labels present in a security object is not restricted to 243 those defined in this document. However, it is not recommended that 244 additional fields be added to a structure unless this is going to be 245 done in a closed environment. When new fields need to be added, it 246 is recommended that a new message type be created so that processing 247 of the field can be ensured. Using an older structure with a new 248 field means that any security properties of the new field will not be 249 enforced. Before a new field is added at the outer level, strong 250 consideration needs to be given to defining a new header field and 251 placing it into the protected headers. Applications should make a 252 determination if non-standardized fields are going to be permitted. 253 It is suggested that libraries allow for an option to fail parsing if 254 non-standardized fields exist, this is especially true if they do not 255 allow for access to the fields in other ways. 257 A field 'msg_type' is defined to distinguish between the different 258 structures when they appear as part of a COSE_MSG object. [CREF2] 259 [CREF3] This field is indexed by an integer value 1, the values 260 defined in this document are: 262 0 - Reserved. 264 1 - Signed Message. 266 2 - Encrypted Message 268 3 - Authenticated Message (MAC-ed message) 270 Implementations MUST be prepared to find an integer under this label 271 which does not correspond to the values 1 to 3. If this is found 272 then the client MUST stop attempting to parse the structure and fail. 273 The value of 0 is reserved and not to be used. If the value of 0 is 274 found, then clients MUST fail processing the structure. 275 Implementations need to recognize that the set of values might be 276 extended at a later date, but they should not provide a security 277 service based on guesses of what is there. 279 NOTE: Is the any reason to allow for a marker of a COSE_Key structure 280 and all it to be a COSE_MSG, doing so does allow for a security risk, 281 but may simplify the code. [CREF4] 283 The CDDL grammar that corresponds to the above is: 285 COSE_MSG = COSE_Sign / 286 COSE_encrypt / 287 COSE_mac 289 COSE_Tagged_MSG = #6.999(COSE_MSG) ; Replace 999 with TBD1 291 ; msg_type values 292 reserved=0 293 msg_type_signed=1 294 msg_type_encrypted=2 295 msg_type_mac=3 297 The top level of each of the COSE message structures are encoded as 298 maps. We use an integer to distinguish between the different 299 security message types. By searching for the integer under the label 300 identified by msg_type (which is in turn an integer), one can 301 determine which security message is being used and thus what syntax 302 is for the rest of the elements in the map. 304 +-------------+--------+--------------------------------------------+ 305 | name | number | comments | 306 +-------------+--------+--------------------------------------------+ 307 | msg_type | 1 | Occurs only in top level messages | 308 | | | | 309 | protected | 2 | Occurs in all structures | 310 | | | | 311 | unprotected | 3 | Occurs in all structures | 312 | | | | 313 | payload | 4 | Contains the content of the structure | 314 | | | | 315 | signatures | 5 | For COSE_Sign - array of signatures | 316 | | | | 317 | signature | 6 | For COSE_signature only | 318 | | | | 319 | ciphertext | 4 | TODO: Should we re-use the same as payload | 320 | | | or not? | 321 | | | | 322 | recipients | 9 | For COSE_encrypt and COSE_mac | 323 | | | | 324 | tag | 10 | For COSE_mac only | 325 +-------------+--------+--------------------------------------------+ 327 Table 1: COSE Map Labels 329 The CDDL grammar that provides the label values is: 331 ; message_keys 332 msg_type=1 333 protected=2 334 unprotected=3 335 payload=4 336 signatures=5 337 signature=6 338 ciphertext=4 339 recipients=9 340 tag=10 342 3. Header Parameters 344 The structure of COSE has been designed to have two buckets of 345 information that are not considered to be part of the payload itself, 346 but are used for holding information about algorithms, keys, or 347 evaluation hints for the processing of the layer. These two buckets 348 are available for use in all of the structures in this document 349 except for keys. While these buckets can be present, they may not 350 all be usable in all instances. For example, while the protected 351 bucket is present for recipient structures, most of the algorithms 352 that are used for recipients do not provide the necessary 353 functionality to provide the needed protection and thus the element 354 is not used. 356 Both buckets are implemented as CBOR maps. The map key is a 'label' 357 Section 1.4. The value portion is dependent on the definition for 358 the label. Both maps use the same set of label/value pairs. The 359 integer range for labels has been divided into several sections with 360 a standard range, a private range, and a range that is dependent on 361 the algorithm selected. The tables of labels can be found in 362 Table 2. 364 Two buckets are provided for each layer: [CREF5] 366 protected contains attributes about the layer which are to be 367 cryptographically protected. This bucket MUST NOT be used if it 368 is not going to be included in a cryptographic computation. 370 unprotected contains attributes about the layer which are not 371 cryptographically protected. 373 Both of the buckets are optional and are omitted if there are no 374 items contained in the map. The CDDL fragment which describes the 375 two buckets is: 377 header_map = {+ label => any } 379 Headers = ( 380 ? protected => bstr, 381 ? unprotected => header_map 382 ) 384 3.1. COSE Headers 386 The set of header fields defined in this document are: 388 alg This field is used to indicate the algorithm used for the 389 security processing. This field MUST be present at each level of 390 a signed, encrypted or authenticated message. This field using 391 the integer '1' for the label. The value is taken from the 'COSE 392 Algorithm Registry' (see Section 9.4). 394 crit This field is used to ensure that applications will take 395 appropriate action based on the values found. This field uses the 396 integer '2' for the label. The value is an array of COSE Header 397 Labels. The field is used to indicate which protected header keys 398 an application which is processing a message is required to 399 understand. 401 Integer keys in the range of 0 to 10 SHOULD be omitted. 403 Integer keys in the range -1 to -255 can be omitted as they are 404 algorithm dependent. If an application can correctly process 405 an algorithm, it can be assumed that it will correctly process 406 all of the parameters associated with that algorithm. 408 The header values indicated by 'crit' can be processed by either 409 the security library code or by an application using a security 410 library, the only requirement is that the field is processed. 412 cty This field is used to indicate the content type of the data in 413 the payload or ciphertext fields. The field uses the integer of 414 '3' for the key value. The value can be either an integer or a 415 string. Integers are from the XXXXX[CREF6] IANA registry table. 416 Strings are from the IANA 'mime-content types' registry. 417 Applications SHOULD provide this field if the content structure is 418 potentially ambiguous. 420 kid This field one of the ways that can be used to find the key to 421 be used. This value can be matched against the 'kid' field in a 422 COSE_Key structure. Applications MUST NOT assume that 'kid' 423 values are unique. There may be more than one key with the same 424 'kid' value, it may be required that all of the keys need to be 425 checked to find the correct one. This field uses the integer 426 value of '4' for the key value. The value of field is the CBOR 427 'bstr' type. The internal structure of 'kid' is not defined and 428 generally cannot be relied on by applications. 430 This table contains a list of all of the parameters for use in 431 signature and encryption message types defined by the JOSE document 432 set. In the table is the data value type to be used for CBOR as well 433 as the integer value that can be used as a replacement for the name 434 in order to further decrease the size of the sent item. 436 +----------+-------+----------+-----------+-------------------------+ 437 | name | label | value | registry | description | 438 +----------+-------+----------+-----------+-------------------------+ 439 | alg | 1 | int / | COSE | Integers are taken from | 440 | | | tstr | Algorithm | table Appendix E | 441 | | | | Registry | | 442 | | | | | | 443 | crit | 2 | [+ | COSE | integer values are from | 444 | | | label] | Header | this table. | 445 | | | | Label | | 446 | | | | Registry | | 447 | | | | | | 448 | cty | 3 | tstr / | | Value is either a mime- | 449 | | | int | | content type or an | 450 | | | | | integer from the mime- | 451 | | | | | content type table | 452 | | | | | | 453 | jku | * | tstr | | URL to COSE key object | 454 | | | | | | 455 | jwk | * | COSE_Key | | contains a COSE key not | 456 | | | | | a JWK key | 457 | | | | | | 458 | kid | 4 | bstr | | key identifier | 459 | | | | | | 460 | x5c | * | bstr* | | X.509 Certificate Chain | 461 | | | | | | 462 | x5t | * | bstr | | SHA-1 thumbprint of key | 463 | | | | | | 464 | x5t#S256 | * | bstr | | SHA-256 thumbprint of | 465 | | | | | key | 466 | | | | | | 467 | x5u | * | tstr | | URL for X.509 | 468 | | | | | certificate | 469 | | | | | | 470 | zip | * | int / | | Integers are taken from | 471 | | | tstr | | the table Appendix E | 472 +----------+-------+----------+-----------+-------------------------+ 474 Table 2: Header Keys 476 OPEN ISSUES: 478 1. Which of the following items do we want to have standardized in 479 this document: jku, jwk, x5c, x5t, x5t#S256, x5u, zip 481 2. I am currently torn on the question "Should epk and iv/nonce be 482 algorithm specific or generic headers?" They are really specific 483 to an algorithm and can potentially be defined in different ways 484 for different algorithms. As an example, it would make sense to 485 defined nonce for CCM and GCM modes that can have the leading 486 zero bytes stripped, while for other algorithms this might be 487 undesirable. 489 3. We might want to define some additional items. What are they? A 490 possible example would be a sequence number as this might be 491 common. On the other hand, this is the type of things that is 492 frequently used as the nonce in some places and thus should not 493 be used in the same way. Other items might be challenge/response 494 fields for freshness as these are likely to be common. 496 4. Signing Structure 498 The signature structure allows for one or more signatures to be 499 applied to a message payload. There are provisions for attributes 500 about the content and attributes about the signature to be carried 501 along with the signature itself. These attributes may be 502 authenticated by the signature, or just present. Examples of 503 attributes about the content would be the type of content, when the 504 content was created, and who created the content. Examples of 505 attributes about the signature would be the algorithm and key used to 506 create the signature, when the signature was created, and counter- 507 signatures. 509 When more than one signature is present, the successful validation of 510 one signature associated with a given signer is usually treated as a 511 successful signature by that signer. However, there are some 512 application environments where other rules are needed. An 513 application that employs a rule other than one valid signature for 514 each signer must specify those rules. Also, where simple matching of 515 the signer identifier is not sufficient to determine whether the 516 signatures were generated by the same signer, the application 517 specification must describe how to determine which signatures were 518 generated by the same signer. Support of different communities of 519 recipients is the primary reason that signers choose to include more 520 than one signature. For example, the COSE_Sign structure might 521 include signatures generated with the RSA signature algorithm and 522 with the Elliptic Curve Digital Signature Algorithm (ECDSA) signature 523 algorithm. This allows recipients to verify the signature associated 524 with one algorithm or the other. (The original source of this text 525 is [RFC5652].) More detailed information on multiple signature 526 evaluation can be found in [RFC5752]. 528 The CDDL grammar for a signature message is: 530 COSE_Sign = { 531 msg_type => msg_type_signed, 532 Headers, 533 ? payload => bstr, 534 signatures => [+ COSE_signature] 535 } 537 The fields is the structure have the following semantics: 539 msg_type identifies this as providing the signed security service. 540 The value MUST be msg_type_signed (1). 542 protected contains attributes about the payload which are to be 543 protected by the signature. An example of such an attribute would 544 be the content type ('cty') attribute. The content is a CBOR map 545 of attributes which is encoded to a byte stream. This field MUST 546 NOT contain attributes about the signature, even if those 547 attributes are common across multiple signatures. The labels in 548 this map are typically taken from Table 2. 550 unprotected contains attributes about the payload which are not 551 protected by the signature. An example of such an attribute would 552 be the content type ('cty') attribute. This field MUST NOT 553 contain attributes about a signature, even if the attributes are 554 common across multiple signatures. The labels in this map are 555 typically taken from Table 2. 557 payload contains the serialized content to be signed. 558 If the payload is not present in the message, the application is 559 required to supply the payload separately. 560 The payload is wrapped in a bstr to ensure that it is transported 561 without changes, if the payload is transported separately it is 562 the responsibility of the application to ensure that it will be 563 transported without changes. 565 signatures is an array of signature items. Each of these items uses 566 the COSE_signature structure for its representation. 568 We use the values in Table 1 as the labels in the COSE_Sign map. 569 While other labels can be present in the map, it is not generally a 570 recommended practice. The other labels can be either of integer or 571 string type, use of other types SHOULD be treated as an error. 573 The CDDL grammar structure for a signature is: 575 COSE_signature = { 576 Headers, 577 signature => bstr 578 } 580 The fields in the structure have the following semantics: 582 protected contains additional information to be authenticated by the 583 signature. The field holds data about the signature operation. 584 The field MUST NOT hold attributes about the payload being signed. 585 The content is a CBOR map of attributes which is encoded to a byte 586 stream. At least one of protected and unprotected MUST be 587 present. 589 unprotected contains attributes about the signature which are not 590 protected by the signature. This field MUST NOT contain 591 attributes about the payload being signed. At least one of 592 protected and unprotected MUST be present. 594 signature contains the computed signature value. 596 The COSE structure used to create the byte stream to be signed uses 597 the following CDDL grammar structure: 599 Sig_structure = [ 600 body_protected: bstr, 601 sign_protected: bstr, 602 payload: bstr 603 ] 605 How to compute a signature: 607 1. Create a Sig_structure object and populate it with the 608 appropriate fields. For body_protected and sign_protected, if 609 the fields are not present in their corresponding maps, an bstr 610 of length zero is used. 612 2. Create the value ToBeSigned by encoding the Sig_structure to a 613 byte string. 615 3. Call the signature creation algorithm passing in K (the key to 616 sign with), alg (the algorithm to sign with) and ToBeSigned (the 617 value to sign). 619 4. Place the resulting signature value in the 'signature' field of 620 the map. 622 How to verify a signature: 624 1. Create a Sig_structure object and populate it with the 625 appropriate fields. For body_protected and sign_protected, if 626 the fields are not present in their corresponding maps, an bstr 627 of length zero is used. 629 2. Create the value ToBeSigned by encoding the Sig_structure to a 630 byte string. 632 3. Call the signature verification algorithm passing in K (the key 633 to verify with), alg (the algorithm to sign with), ToBeSigned 634 (the value to sign), and sig (the signature to be verified). 636 In addition to performing the signature verification, one must also 637 perform the appropriate checks to ensure that the key is correctly 638 paired with the signing identity and that the appropriated 639 authorization is done. 641 5. Encryption object 643 In this section we describe the structure and methods to be used when 644 doing an encryption in COSE. In COSE, we use the same techniques and 645 structures for encrypting both the plain text and the keys used to 646 protect the text. This is different from the approach used by both 647 [RFC5652] and [RFC7516] where different structures are used for the 648 plain text and for the different key management techniques. 650 One of the byproducts of using the same technique for encrypting and 651 encoding both the content and the keys using the various key 652 management techniques, is a requirement that all of the key 653 management techniques use an Authenticated Encryption (AE) algorithm. 654 (For the purpose of this document we use a slightly loose definition 655 of AE algorithms.) When encrypting the plain text, it is normal to 656 use an Authenticated Encryption with Additional Data (AEAD) 657 algorithm. For key management, either AE or AEAD algorithms can be 658 used. See Appendix A for more details about the different types of 659 algorithms. [CREF7] 661 The CDDL grammar structure for encryption is: 663 COSE_encrypt = { 664 msg_type=>msg_type_encrypted, 665 COSE_encrypt_fields 666 } 668 COSE_encrypt_fields = ( 669 Headers, 670 ? ciphertext => bstr, 671 ? recipients => [+{COSE_encrypt_fields}] 672 ) 674 Description of the fields: 676 msg_type identifies this as providing the encrypted security 677 service. The value MUST be msg_type_encrypted (2). 679 protected contains the information about the plain text or 680 encryption process that is to be integrity protected. The field 681 is encoded in CBOR as a 'bstr'. The contents of the protected 682 field is a CBOR map of the protected data names and values. The 683 map is CBOR encoded before placing it into the bstr. Only values 684 associated with the current cipher text are to be placed in this 685 location even if the value would apply to multiple recipient 686 structures. 688 unprotected contains information about the plain text that is not 689 integrity protected. Only values associated with the current 690 cipher text are to be placed in this location even if the value 691 would apply to multiple recipient structures. 693 cipherText contains the encrypted plain text. If the cipherText is 694 to be transported independently of the control information about 695 the encryption process (i.e. detached content) then the field is 696 omitted. 698 recipients contains the recipient information. It is required that 699 at least one recipient MUST be present for the content encryption 700 layer. 702 5.1. Key Management Methods 704 There are a number of different key management methods that can be 705 used in the COSE encryption system. In this section we will discuss 706 each of the key management methods and what fields need to be 707 specified to deal with each of them. 709 The names of the key management methods used here are the same as are 710 defined in [RFC7517]. Other specifications use different terms for 711 the key management methods or do not support some of the key 712 management methods. 714 At the moment we do not have any key management methods that allow 715 for the use of protected headers. This may be changed in the future 716 if, for example, the AES-GCM Key wrap method defined in [RFC7518] 717 were extended to allow for authenticated data. In that event the use 718 of the 'protected' field, which is current forbidden below, would be 719 permitted. 721 5.1.1. Direct Encryption 723 In direct encryption mode, a shared secret between the sender and the 724 recipient is used as the CEK. When direct encryption mode is used, 725 it MUST be the only mode used on the message. It is a massive 726 security leak to have both direct encryption and a different key 727 management mode on the same message. 729 For JOSE, direct encryption key management is the only key management 730 method allowed for doing MAC-ed messages. In COSE, all of the key 731 management methods can be used for MAC-ed messages. 733 The COSE_encrypt structure for the recipient is organized as follows: 735 o The 'protected', 'ciphertext' and 'recipients' fields MUST be 736 absent. 738 o At a minimum, the 'unprotected' field MUST contain the 'alg' 739 parameter and SHOULD contain a parameter identifying the shared 740 secret. 742 5.1.2. Key Wrapping 744 In key wrapping mode, the CEK is randomly generated and that key is 745 then encrypted by a shared secret between the sender and the 746 recipient. All of the currently defined key wrapping algorithms for 747 JOSE (and thus for COSE) are AE algorithms. Key wrapping mode is 748 considered to be superior to direct encryption if the system has any 749 capability for doing random key generation. This is because the 750 shared key is used to wrap random data rather than data has some 751 degree of organization and may in fact be repeating the same content. 753 The COSE_encrypt structure for the recipient is organized as follows: 755 o The 'protected', and 'recipients' fields MUST be absent. 757 o The plain text to be encrypted is the key from next layer down 758 (usually the content layer). 760 o At a minimum, the 'unprotected' field MUST contain the 'alg' 761 parameter and SHOULD contain a parameter identifying the shared 762 secret. 764 5.1.3. Key Encryption 766 Key Encryption mode is also called key transport mode in some 767 standards. Key Encryption mode differs from Key Wrap mode in that it 768 uses an asymmetric encryption algorithm rather than a symmetric 769 encryption algorithm to protect the key. The only current Key 770 Encryption mode algorithm supported is RSAES-OAEP. 772 The COSE_encrypt structure for the recipient is organized as follows: 774 o The 'protected' field MUST be absent. 776 o The plain text to be encrypted is the key from next layer down 777 (usually the content layer). 779 o At a minimum, the 'unprotected' field MUST contain the 'alg' 780 parameter and SHOULD contain a parameter identifying the 781 asymmetric key. 783 5.1.4. Direct Key Agreement 785 Direct Key Agreement derives the CEK from the shared secret computed 786 by the key agreement operation. 788 When direct key agreement mode is used, it SHOULD be the only mode 789 used on the message. This method creates the CEK directly and that 790 makes it difficult to mix with additional recipients. 792 The COSE_encrypt structure for the recipient is organized as follows: 794 o The 'protected' field MUST be absent. 796 o At a minimum, the 'unprotected' field MUST contain the 'alg' 797 parameter and SHOULD contain a parameter identifying the 798 asymmetric key. 800 o The 'unprotected' field MUST contain the 'epk' parameter. 802 5.1.5. Key Agreement with Key Wrapping 804 Key Agreement with Key Wrapping uses a randomly generated CEK. The 805 CEK is then encrypted using a Key Wrapping algorithm and a key 806 derived from the shared secret computed by the key agreement 807 algorithm. 809 The COSE_encrypt structure for the recipient is organized as follows: 811 o The 'protected' field MUST be absent. 813 o The plain text to be encrypted is the key from next layer down 814 (usually the content layer). 816 o At a minimum, the 'unprotected' field MUST contain the 'alg' 817 parameter, a parameter identifying the recipient asymmetric key, 818 and a parameter with the sender's asymmetric public key. 820 5.2. Encryption Algorithm for AEAD algorithms 822 The encryption algorithm for AEAD algorithms is fairly simple. 823 In order to get a consistent encoding of the data to be 824 authenticated, the Enc_structure is used to have canonical form of 825 the AAD. 827 Enc_structure = [ 828 protected: bstr, 829 external_aad: bstr 830 ] 832 1. Copy the protected header field from the message to be sent. 834 2. If the application has supplied external additional authenticated 835 data to be included in the computation, then it is placed in the 836 'external_aad' field. If no data was supplied, then a zero 837 length binary value is used. 839 3. Encode the Enc_structure using a CBOR Canonical encoding 840 Section 8 to get the AAD value. 842 4. Determine the encryption key. This step is dependent on the key 843 management method being used: For: 845 No Recipients: The key to be used is determined by the algorithm 846 and key at the current level. 848 Direct and Direct Key Agreement: The key is determined by the 849 key and algorithm in the recipient structure. The encryption 850 algorithm and size of the key to be used are inputs into the 851 KDF used for the recipient. (For direct, the KDF can be 852 thought of as the identity operation.) 854 Other: The key is randomly generated. 856 5. Call the encryption algorithm with K (the encryption key to use), 857 P (the plain text) and AAD (the additional authenticated data). 858 Place the returned cipher text into the 'ciphertext' field of the 859 structure. 861 6. For recipients of the message, recursively perform the encryption 862 algorithm for that recipient using the encryption key as the 863 plain text. 865 5.3. Encryption algorithm for AE algorithms 867 1. Verify that the 'protected' field is absent. 869 2. Verify that there was no external additional authenticated data 870 supplied for this operation. 872 3. Determine the encryption key. This step is dependent on the key 873 management method being used: For: 875 No Recipients: The key to be used is determined by the algorithm 876 and key at the current level. 878 Direct and Direct Key Agreement: The key is determined by the 879 key and algorithm in the recipient structure. The encryption 880 algorithm and size of the key to be used are inputs into the 881 KDF used for the recipient. (For direct, the KDF can be 882 thought of as the identity operation.) 884 Other: The key is randomly generated. 886 4. Call the encryption algorithm with K (the encryption key to use) 887 and the P (the plain text). Place the returned cipher text into 888 the 'ciphertext' field of the structure. 890 5. For recipients of the message, recursively perform the encryption 891 algorithm for that recipient using the encryption key as the 892 plain text. 894 6. MAC objects 896 In this section we describe the structure and methods to be used when 897 doing MAC authentication in COSE. JOSE used a variant of the 898 signature structure for doing MAC operations and it is restricted to 899 using a single pre-shared secret to do the authentication. This 900 document allows for the use of all of the same methods of key 901 management as are allowed for encryption. 903 When using MAC operations, there are two modes in which it can be 904 used. The first is just a check that the content has not been 905 changed since the MAC was computed. Any of the key management 906 methods can be used for this purpose. The second mode is to both 907 check that the content has not been changed since the MAC was 908 computed, and to use key management to verify who sent it. The key 909 management modes that support this are ones that either use a pre- 910 shared secret, or do static-static key agreement. In both of these 911 cases the entity MAC-ing the message can be validated by a key 912 binding. (The binding of identity assumes that there are only two 913 parties involved and you did not send the message yourself.) 915 COSE_mac = { 916 msg_type=>msg_type_mac, 917 Headers, 918 ? payload => bstr, 919 tag => bstr, 920 recipients => [+{COSE_encrypt_fields}] 921 } 923 Field descriptions: 925 msg_type identifies this as providing the encrypted security 926 service. The value MUST be msg_type_mac (3). 928 protected contains attributes about the payload which are to be 929 protected by the MAC. An example of such an attribute would be 930 the content type ('cty') attribute. The content is a CBOR map of 931 attributes which is encoded to a byte stream. This field MUST NOT 932 contain attributes about the recipient, even if those attributes 933 are common across multiple recipients. At least one of protected 934 and unprotected MUST be present. 936 unprotected contains attributes about the payload which are not 937 protected by the MAC. An example of such an attribute would be 938 the content type ('cty') attribute. This field MUST NOT contain 939 attributes about a recipient, even if the attributes are common 940 across multiple recipients. At least one of protected and 941 unprotected MUST be present. 943 payload contains the serialized content to be MAC-ed. 944 If the payload is not present in the message, the application is 945 required to supply the payload separately. 946 The payload is wrapped in a bstr to ensure that it is transported 947 without changes, if the payload is transported separately it is 948 the responsibility of the application to ensure that it will be 949 transported without changes. 951 tag contains the MAC value. 953 recipients contains the recipient information. See the description 954 under COSE_Encryption for more info. 956 MAC_structure = [ 957 protected: bstr, 958 external_aad: bstr, 959 payload: bstr 960 ] 962 How to compute a MAC: 964 1. Create a MAC_structure and copy the protected and payload 965 elements from the COSE_mac structure. 967 2. If the application has supplied external authenticated data, 968 encode it as a binary value and place in the MAC_structure. If 969 there is no external authenticated data, then use a zero length 970 'bstr'. 972 3. Encode the MAC_structure using a canonical CBOR encoder. The 973 resulting bytes is the value to compute the MAC on. 975 4. Compute the MAC and place the result in the 'tag' field of the 976 COSE_mac structure. 978 5. Encrypt and encode the MAC key for each recipient of the message. 980 7. Key Structure 982 There are only a few changes between JOSE and COSE for how keys are 983 formatted. As with JOSE, COSE uses a map to contain the elements of 984 a key. Those values, which in JOSE, are base64url encoded because 985 they are binary values, are encoded as bstr values in COSE. 987 For COSE we use the same set of fields that were defined in 988 [RFC7517]. 990 COSE_Key = { 991 kty => tstr / int, 992 ? key_ops => [+ tstr / int ], 993 ? alg => tstr / int, 994 ? kid => bstr, 995 * keys => values 996 } 998 COSE_KeySet = [+COSE_Key] 1000 The element "kty" is a required element in a COSE_Key map. 1001 All other elements are optional and not all of the elements listed in 1002 [RFC7517] or [RFC7518] have been listed here even though they can all 1003 appear in a COSE_Key map. 1005 The "key_ops" element is preferred over the "use" element as the 1006 information provided that way is more finely detailed about the 1007 operations allowed. It is strongly suggested that this element be 1008 present for all keys. 1010 The same fields defined in [RFC7517] are used here with the following 1011 changes in rules: 1013 o Any item which is base64 encoded in JWK, is bstr encoded for COSE. 1015 o Any item which is integer encoded in JWK, is int encoded for COSE. 1017 o Any item which is string (but not base64) encoded in JWK, is tstr 1018 encoded for COSE. 1020 o Exceptions to this are the following fields: 1022 kid is always bstr encoded rather than tstr encoded. This change 1023 in encoded is due to the fact that frequently, values such as a 1024 hash of the public key is used for a kid value. Since the 1025 field is defined as not having a specific structure, making it 1026 binary rather than textual makes sense. 1028 8. CBOR Encoder Restrictions 1030 There as been an attempt to limit the number of places where the 1031 document needs to impose restrictions on how the CBOR Encoder needs 1032 to work. We have managed to narrow it down to the following 1033 restrictions: 1035 o The restriction applies to the encoding the Sig_structure, the 1036 Enc_structure, and the MAC_structure. 1038 o The rules for Canonical CBOR (Section 3.9 of RFC 7049) MUST be 1039 used in these locations. The main rule that needs to be enforced 1040 is that all lengths in these structures MUST be encoded such that 1041 they are encoded using definite lengths and the minimum length 1042 encoding is used. 1044 o All parsers used SHOULD fail on both parsing and generation if the 1045 same label is used twice as a key for the same map. 1047 9. IANA Considerations 1049 9.1. CBOR Tag assignment 1051 It is requested that IANA assign a new tag from the "Concise Binary 1052 Object Representation (CBOR) Tags" registry. It is requested that 1053 the tag be assigned in the 0 to 23 value range. 1055 Tag Value: TBD1 1057 Data Item: CBOR map 1059 Semantics: COSE security message. 1061 9.2. COSE Object Labels Registry 1063 It is requested that IANA create a new registry entitled "COSE Object 1064 Labels Registry". [CREF8] 1066 This table is initially populated by the table in Table 1. 1068 9.3. COSE Header Label Table 1070 It is requested that IANA create a new registry entitled "COSE Header 1071 Labels". 1073 The columns of the registry are: 1075 name The name is present to make it easier to refer to and discuss 1076 the registration entry. The value is not used in the protocol. 1077 Names are to be unique in the table. 1079 label This is the value used for the label. The label can be either 1080 an integer or a string. Registration in the table is based on the 1081 value of the label requested. Integer values between 0 and 255 1082 and strings of length 1 are designated as Standards Track Document 1083 required. Integer values from 256 to 65535 and strings of length 1084 2 are designated as Specification Required. Integer values of 1085 greater than 65535 and strings of length greater than 2 are 1086 designated as first come first server. Integer values in the 1087 range -1 to -65536 are delegated to the "COSE Header Algorithm 1088 Label" registry. Integer values beyond -65536 are marked as 1089 private use. 1091 value This contains the CBOR type for the value portion of the 1092 label. 1094 value registry This contains a pointer to the registry used to 1095 contain values where the set is limited. 1097 description This contains a brief description of the header field. 1099 specification This contains a pointer to the specification defining 1100 the header field (where public). 1102 The initial contents of the registry can be found in Table 2. The 1103 specification column for all rows in that table should be this 1104 document. 1106 NOTE: Need to review the range assignments. It does not necessarily 1107 make sense as specification required uses 1 byte positive integers 1108 and 2 byte strings. 1110 9.4. COSE Header Algorithm Label Table 1112 It is requested that IANA create a new registry entitled "COSE Header 1113 Algorithm Labels". 1115 The columns of the registry are: 1117 name The name is present to make it easier to refer to and discuss 1118 the registration entry. The value is not used in the protocol. 1120 algorithm The algorithm(s) that this registry entry is used for. 1121 This value is taken from the "COSE Algorithm Value" registry. 1122 Multiple algorithms can be specified in this entry. For the 1123 table, the algorithm, label pair MUST be unique. 1125 label This is the value used for the label. The label is an integer 1126 in the range of -1 to -65536. 1128 value This contains the CBOR type for the value portion of the 1129 label. 1131 value registry This contains a pointer to the registry used to 1132 contain values where the set is limited. 1134 description This contains a brief description of the header field. 1136 specification This contains a pointer to the specification defining 1137 the header field (where public). 1139 The initial contents of the registry can be found in Appendix D. The 1140 specification column for all rows in that table should be this 1141 document. 1143 9.5. COSE Algorithm Registry 1145 It is requested that IANA create a new registry entitled "COSE 1146 Algorithm Registry". 1148 The columns of the registry are: 1150 value The value to be used to identify this algorithm. Algorithm 1151 values MUST be unique. The value can be a positive integer, a 1152 negative integer or a string. Integer values between 0 and 255 1153 and strings of length 1 are designated as Standards Track Document 1154 required. Integer values from 256 to 65535 and strings of length 1155 2 are designated as Specification Required. Integer values of 1156 greater than 65535 and strings of length greater than 2 are 1157 designated as first come first server. Integer values in the 1158 range -1 to -65536 are delegated to the "COSE Header Algorithm 1159 Label" registry. Integer values beyond -65536 are marked as 1160 private use. 1162 description A short description of the algorithm. 1164 specification A document where the algorithm is defined (if publicly 1165 available). 1167 The initial contents of the registry can be found in Appendix E. The 1168 specification column for all rows in that table should be this 1169 document. 1171 9.6. COSE Key Map Registry 1173 It is requested that IANA create a new registry entitled "COSE Key 1174 Map Registry". 1176 The columns of the registry are: 1178 name This is a descriptive name that enables easier reference to the 1179 item. It is not used in the encoding. 1181 label The value to be used to identify this algorithm. Algorithm 1182 labels MUST be unique. The label can be a positive integer, a 1183 negative integer or a string. Integer values between 0 and 255 1184 and strings of length 1 are designated as Standards Track Document 1185 required. Integer values from 256 to 65535 and strings of length 1186 2 are designated as Specification Required. Integer values of 1187 greater than 65535 and strings of length greater than 2 are 1188 designated as first come first server. Integer values in the 1189 range -1 to -65536 are used for key parameters specific to a 1190 single algorithm delegated to the "COSE Key Parameter Label" 1191 registry. Integer values beyond -65536 are marked as private use. 1193 CBOR Type This field contains the CBOR type for the field 1195 registry This field denotes the registry that values come from, if 1196 one exists. 1198 description This field contains a brief description for the field 1200 specification This contains a pointer to the public specification 1201 for the field if one exists 1203 This registry will be initially populated by the values in 1204 Appendix G. The specification column for all of these entries will 1205 be this document. 1207 9.7. COSE Key Parameter Registry 1209 It is requested that IANA create a new registry "COSE Key 1210 Parameters". 1212 The columns of the table are: 1214 key type This field contains a descriptive string of a key type. 1215 This should be a value that is in the COSE General Values table 1216 and is placed in the 'kty' field of a COSE Key structure. 1218 name This is a descriptive name that enables easier reference to the 1219 item. It is not used in the encoding. 1221 label The label is to be unique for every value of key type. The 1222 range of values is from -256 to -1. Keys are expected to be re- 1223 used for different keys. 1225 CBOR type This field contains the CBOR type for the field 1227 description This field contains a brief description for the field 1228 specification This contains a pointer to the public specification 1229 for the field if one exists 1231 This registry will be initially populated by the values in 1232 Appendix H. The specification column for all of these entries will 1233 be this document. 1235 9.8. Media Type Registration 1237 9.8.1. COSE Security Message 1239 This section registers the "application/cose" and "application/ 1240 cose+cbor" media types in the "Media Types" registry. [CREF9] These 1241 media types are used to indicate that the content is a COSE_MSG. 1243 Type name: application 1245 Subtype name: cose 1247 Required parameters: N/A 1249 Optional parameters: N/A 1251 Encoding considerations: binary 1253 Security considerations: See the Security Considerations section 1254 of RFC TBD. 1256 Interoperability considerations: N/A 1258 Published specification: RFC TBD 1260 Applications that use this media type: To be identified 1262 Fragment identifier considerations: N/A 1264 Additional information: 1266 * Magic number(s): N/A 1268 * File extension(s): cbor 1270 * Macintosh file type code(s): N/A 1272 Person & email address to contact for further information: 1273 iesg@ietf.org 1275 Intended usage: COMMON 1276 Restrictions on usage: N/A 1278 Author: Jim Schaad, ietf@augustcellars.com 1280 Change Controller: IESG 1282 Provisional registration? No 1284 Type name: application 1286 Subtype name: cose+cbor 1288 Required parameters: N/A 1290 Optional parameters: N/A 1292 Encoding considerations: binary 1294 Security considerations: See the Security Considerations section 1295 of RFC TBD. 1297 Interoperability considerations: N/A 1299 Published specification: RFC TBD 1301 Applications that use this media type: To be identified 1303 Fragment identifier considerations: N/A 1305 Additional information: 1307 * Magic number(s): N/A 1309 * File extension(s): cbor 1311 * Macintosh file type code(s): N/A 1313 Person & email address to contact for further information: 1314 iesg@ietf.org 1316 Intended usage: COMMON 1318 Restrictions on usage: N/A 1320 Author: Jim Schaad, ietf@augustcellars.com 1322 Change Controller: IESG 1323 Provisional registration? No 1325 9.8.2. COSE Key media type 1327 This section registers the "application/jwk+json" and "application/ 1328 jwk-set+json" media typesin the "Media Types" registry. These media 1329 types are used to indicate, respectively, that content is a COSE_Key 1330 or COSE_KeySet object. 1332 Type name: application 1334 Subtype name: cose-key+cbor 1336 Required parameters: N/A 1338 Optional parameters: N/A 1340 Encoding considerations: binary 1342 Security considerations: See the Security Considerations section 1343 of RFC TBD. 1345 Interoperability considerations: N/A 1347 Published specification: RFC TBD 1349 Applications that use this media type: To be identified 1351 Fragment identifier considerations: N/A 1353 Additional information: 1355 * Magic number(s): N/A 1357 * File extension(s): cbor 1359 * Macintosh file type code(s): N/A 1361 Person & email address to contact for further information: 1362 iesg@ietf.org 1364 Intended usage: COMMON 1366 Restrictions on usage: N/A 1368 Author: Jim Schaad, ietf@augustcellars.com 1370 Change Controller: IESG 1371 Provisional registration? No 1373 Type name: application 1375 Subtype name: cose-key-set+cbor 1377 Required parameters: N/A 1379 Optional parameters: N/A 1381 Encoding considerations: binary 1383 Security considerations: See the Security Considerations section 1384 of RFC TBD. 1386 Interoperability considerations: N/A 1388 Published specification: RFC TBD 1390 Applications that use this media type: To be identified 1392 Fragment identifier considerations: N/A 1394 Additional information: 1396 * Magic number(s): N/A 1398 * File extension(s): cbor 1400 * Macintosh file type code(s): N/A 1402 Person & email address to contact for further information: 1403 iesg@ietf.org 1405 Intended usage: COMMON 1407 Restrictions on usage: N/A 1409 Author: Jim Schaad, ietf@augustcellars.com 1411 Change Controller: IESG 1413 Provisional registration? No 1415 10. Security Considerations 1417 There are security considerations: 1419 1. Protect private keys 1421 2. MAC messages with more than one recipient means one cannot figure 1422 out who sent the message 1424 3. Use of direct key with other recipient structures hands the key 1425 to other recipients. 1427 4. Use of direct ECDH direct encryption is easy for people to leak 1428 information on if there are other recipients in the message. 1430 5. Considerations about protected vs unprotected header fields. 1432 11. References 1434 11.1. Normative References 1436 [I-D.greevenbosch-appsawg-cbor-cddl] 1437 Vigano, C., Birkholz, H., and R. Sun, "CBOR data 1438 definition language: a notational convention to express 1439 CBOR data structures.", draft-greevenbosch-appsawg-cbor- 1440 cddl-05 (work in progress), March 2015. 1442 [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object 1443 Representation (CBOR)", RFC 7049, October 2013. 1445 11.2. Informative References 1447 [AES-GCM] Dworkin, M., "NIST Special Publication 800-38D: 1448 Recommendation for Block Cipher Modes of Operation: 1449 Galois/Counter Mode (GCM) and GMAC.", June 2015. 1451 [I-D.mcgrew-aead-aes-cbc-hmac-sha2] 1452 McGrew, D., Foley, J., and K. Paterson, "Authenticated 1453 Encryption with AES-CBC and HMAC-SHA", draft-mcgrew-aead- 1454 aes-cbc-hmac-sha2-05 (work in progress), July 2014. 1456 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1457 Requirement Levels", BCP 14, RFC 2119, March 1997. 1459 [RFC3394] Schaad, J. and R. Housley, "Advanced Encryption Standard 1460 (AES) Key Wrap Algorithm", RFC 3394, September 2002. 1462 [RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography 1463 Standards (PKCS) #1: RSA Cryptography Specifications 1464 Version 2.1", RFC 3447, February 2003. 1466 [RFC3610] Whiting, D., Housley, R., and N. Ferguson, "Counter with 1467 CBC-MAC (CCM)", RFC 3610, September 2003. 1469 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 1470 RFC 5652, September 2009. 1472 [RFC5752] Turner, S. and J. Schaad, "Multiple Signatures in 1473 Cryptographic Message Syntax (CMS)", RFC 5752, January 1474 2010. 1476 [RFC5990] Randall, J., Kaliski, B., Brainard, J., and S. Turner, 1477 "Use of the RSA-KEM Key Transport Algorithm in the 1478 Cryptographic Message Syntax (CMS)", RFC 5990, September 1479 2010. 1481 [RFC7159] Bray, T., "The JavaScript Object Notation (JSON) Data 1482 Interchange Format", RFC 7159, March 2014. 1484 [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web 1485 Signature (JWS)", RFC 7515, May 2015. 1487 [RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", 1488 RFC 7516, May 2015. 1490 [RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517, May 2015. 1492 [RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518, May 1493 2015. 1495 Appendix A. AEAD and AE algorithms 1497 The set of encryption algorithms that can be used with this 1498 specification is restricted to authenticated encryption (AE) and 1499 authenticated encryption with additional data (AEAD) algorithms. 1500 This means that there is a strong check that the data decrypted by 1501 the recipient is the same as what was encrypted by the sender. 1502 Encryption modes such as counter have no check on this at all. The 1503 CBC encryption mode had a weak check that the data is correct, given 1504 a random key and random data, the CBC padding check will pass one out 1505 of 256 times. There have been several times that a normal encryption 1506 mode has been combined with an integrity check to provide a content 1507 encryption mode that does provide the necessary authentication. AES- 1508 GCM [AES-GCM], AES-CCM [RFC3610], AES-CBC-HMAC 1510 [I-D.mcgrew-aead-aes-cbc-hmac-sha2] are examples of these composite 1511 modes. 1513 2PKCS v1.5 RSA key transport does not qualify as an AE algorithm. 1514 There are only three bytes in the encoding that can be checked as 1515 having decrypted correctly, the rest of the content can only be 1516 probabilistically checked as having decrypted correctly. For this 1517 reason, PKCS v1.5 RSA key transport MUST NOT be used with this 1518 specification. RSA-OAEP was designed to have the necessary checks 1519 that that content correctly decrypted and does qualify as an AE 1520 algorithm. 1522 When dealing with authenticated encryption algorithms, there is 1523 always some type of value that needs to be checked to see if the 1524 authentication level has passed. This authentication value may be: 1526 o A separately generated tag computed by both the encrypter and 1527 decrypter and then compared by the decryptor. This tag value may 1528 be either placed at the end of the cipher text (the decision we 1529 made) or kept separately (the decision made by the JOSE working 1530 group). This is the approach followed by AES-GCM [AES-GCM] and 1531 AES-CCM [RFC3610]. 1533 o A fixed value which is part of the encoded plain text. This is 1534 the approach followed by the AES key wrap algorithm [RFC3394]. 1536 o A computed value is included as part of the encoded plain text. 1537 The computed value is then checked by the decryptor using the same 1538 computation path. This is the approach followed by RSAES-OAEP 1539 [RFC3447]. 1541 Appendix B. Three Levels of Recipient Information 1543 All of the currently defined Key Management methods only use two 1544 levels of the COSE_Encrypt structure. The first level is the message 1545 content and the second level is the content key encryption. However, 1546 if one uses a key management technique such as RSA-KEM (see 1547 Appendix A of RSA-KEM [RFC5990], then it make sense to have three 1548 levels of the COSE_Encrypt structure. 1550 These levels would be: 1552 o Level 0: The content encryption level. This level contains the 1553 payload of the message. 1555 o Level 1: The encryption of the CEK by a KEK. 1557 o Level 2: The encryption of a long random secret using an RSA key 1558 and a key derivation function to convert that secret into the KEK. 1560 This is an example of what a triple layer message would look like. 1561 The message has the following layers: 1563 o Level 0: Has a content encrypted with AES-GCM using a 128-bit key. 1565 o Level 1: Uses the AES Key wrap algorithm with a 128-bit key. 1567 o Level 3: Uses ECDH Ephemeral-Static direct to generate the level 1 1568 key. 1570 In effect this example is a decomposed version of using the ECDH- 1571 ES+A128KW algorithm. 1573 { 1574 1: 2, 1575 2: h'a10101', 1576 3: { 1577 -1: h'02d1f7e6f26c43d4868d87ce' 1578 }, 1579 4: h'64f84d913ba60a76070a9a48f26e97e863e285295a44320878caceb076 1580 3a334806857c67', 1581 9: [ 1582 { 1583 3: { 1584 1: -3 1585 }, 1586 4: h'5a15dbf5b282ecb31a6074ee3815c252405dd7583e078188', 1587 9: [ 1588 { 1589 3: { 1590 1: "ECDH-ES", 1591 5: "meriadoc.brandybuck@buckland.example", 1592 4: { 1593 1: 1, 1594 -1: 4, 1595 -2: h'b2add44368ea6d641f9ca9af308b4079aeb519f11e9b8 1596 a55a600b21233e86e68', 1597 -3: h'1a2cf118b9ee6895c8f415b686d4ca1cef362d4a7630a 1598 31ef6019c0c56d33de0' 1599 } 1600 } 1601 } 1602 ] 1603 } 1604 ] 1605 } 1607 Appendix C. Examples 1609 The examples can be found at https://github.com/cose-wg/Examples. I 1610 am currently still in the process of getting the examples up there 1611 along with some control information for people to be able to check 1612 and reproduce the examples. 1614 C.1. Direct MAC 1616 This example has some features that are in questions but not yet 1617 incorporated in the document. 1619 To make it easier to read, this uses CBOR's diagnostic notation 1620 rather than a binary dump. 1622 This example is uses HMAC with SHA-256 as the digest algorithm. The 1623 key management is uses two static ECDH keys along with HKDF to 1624 directly derive the key used in the HMAC operation. 1626 { 1627 1: 3, 1628 2: h'a10104', 1629 4: h'546869732069732074686520636f6e74656e742e', 1630 10: h'2ba937ca03d76c3dbad30cfcbaeef586f9c0f9ba616ad67e9205d3857 1631 6ad9930', 1632 9: [ 1633 { 1634 3: { 1635 1: "ECDH-SS", 1636 5: "meriadoc.brandybuck@buckland.example", 1637 "spk": { 1638 "kid": "peregrin.took@tuckborough.example" 1639 }, 1640 "apu": h'4d8553e7e74f3c6a3a9dd3ef286a8195cbf8a23d19558ccf 1641 ec7d34b824f42d92bd06bd2c7f0271f0214e141fb779ae2856abf585a58368b01 1642 7e7f2a9e5ce4db5' 1643 } 1644 } 1645 ] 1646 } 1648 C.2. Wrapped MAC 1650 This example has some features that are in questions but not yet 1651 incorporated in the document. 1653 To make it easier to read, this uses CBOR's diagnostic notation 1654 rather than a binary dump. 1656 This example uses AES-128-MAC truncated to 64-bits as the digest 1657 algorithm. It uses AES-256 Key wrap for the key management algorithm 1658 wrapping the 128-bit key used for the digest algorithm. 1660 { 1661 1: 3, 1662 2: h'a1016e4145532d3132382d4d41432d3634', 1663 4: h'546869732069732074686520636f6e74656e742e', 1664 10: h'6d1fa77b2dd9146a', 1665 9: [ 1666 { 1667 3: { 1668 1: -5, 1669 5: "018c0ae5-4d9b-471b-bfd6-eef314bc7037" 1670 }, 1671 4: h'711ab0dc2fc4585dce27effa6781c8093eba906f227b6eb0' 1672 } 1673 ] 1674 } 1676 C.3. Multi-recipient MAC message 1678 This example has some features that are in questions but not yet 1679 incorporated in the document. 1681 To make it easier to read, this uses CBOR's diagnostic notation 1682 rather than a binary dump. 1684 This example uses HMAC with SHA-256 for the digest algorithm. There 1685 are three different key management techniques applied: 1687 o An ephemeral static ECDH key agreement operation using AES-128 key 1688 wrap on the digest key. 1690 o Key transport using RSA-OAEP with SHA-256 for the hash and the mfg 1691 function operations. 1693 o AES 256-bit Key wrap using a pre-shared secret. 1695 { 1696 1: 3, 1697 2: h'a10104', 1698 4: h'546869732069732074686520636f6e74656e742e', 1699 10: h'7aaa6e74546873061f0a7de21ff0c0658d401a68da738dd8937486519 1700 83ce1d0', 1701 9: [ 1702 { 1703 3: { 1704 1: "ECDH-ES+A128KW", 1705 5: h'62696c626f2e62616767696e7340686f626269746f6e2e657861 1706 6d706c65', 1707 4: { 1708 1: 1, 1709 -1: 5, 1710 -2: h'43b12669acac3fd27898ffba0bcd2e6c366d53bc4db71f909 1711 a759304acfb5e18cdc7ba0b13ff8c7636271a6924b1ac63c02688075b55ef2d61 1712 3574e7dc242f79c3', 1713 -3: h'812dd694f4ef32b11014d74010a954689c6b6e8785b333d1a 1714 b44f22b9d1091ae8fc8ae40b687e5cfbe7ee6f8b47918a07bb04e9f5b1a51a334 1715 a16bc09777434113' 1716 } 1717 }, 1718 4: h'1b120c848c7f2f8943e402cbdbdb58efb281753af4169c70d0126c 1719 0d16436277160821790ef4fe3f' 1720 }, 1721 { 1722 3: { 1723 1: -2, 1724 5: h'62696c626f2e62616767696e7340686f626269746f6e2e657861 1725 6d706c65' 1726 }, 1727 4: h'46c4f88069b650909a891e84013614cd58a3668f88fa18f3852940 1728 a20b35098591d3aacf91c125a2595cda7bee75a490579f0e2f20fd6bc956623bf 1729 de3029c318f82c426dac3463b261c981ab18b72fe9409412e5c7f2d8f2b5abaf7 1730 80df6a282db033b3a863fa957408b81741878f466dcc437006ca21407181a016c 1731 a608ca8208bd3c5a1ddc828531e30b89a67ec6bb97b0c3c3c92036c0cb84aa0f0 1732 ce8c3e4a215d173bfa668f116ca9f1177505afb7629a9b0b5e096e81d37900e06 1733 f561a32b6bc993fc6d0cb5d4bb81b74e6ffb0958dac7227c2eb8856303d989f93 1734 b4a051830706a4c44e8314ec846022eab727e16ada628f12ee7978855550249cc 1735 b58' 1736 }, 1737 { 1738 3: { 1739 1: -5, 1740 5: "018c0ae5-4d9b-471b-bfd6-eef314bc7037" 1741 }, 1742 4: h'0b2c7cfce04e98276342d6476a7723c090dfdd15f9a518e7736549 1743 e998370695e6d6a83b4ae507bb' 1744 } 1745 ] 1746 } 1748 C.4. Direct ECDH 1750 This example has some features that are in questions but not yet 1751 incorporated in the document. 1753 To make it easier to read, this uses CBOR's diagnostic notation 1754 rather than a binary dump. 1756 Encoded in CBOR - 216 bytes, content is 14 bytes long 1758 { 1759 1: 2, 1760 2: h'a10101', 1761 3: { 1762 -1: h'c9cf4df2fe6c632bf7886413' 1763 }, 1764 4: h'45fce2814311024d3a479e7d3eed063850f3f0b9f3f948677e3ae9869b 1765 cf9ff4e1763812', 1766 9: [ 1767 { 1768 3: { 1769 1: "ECDH-ES", 1770 5: "meriadoc.brandybuck@buckland.example", 1771 4: { 1772 1: 1, 1773 -1: 4, 1774 -2: h'98f50a4ff6c05861c8860d13a638ea56c3f5ad7590bbfbf05 1775 4e1c7b4d91d6280', 1776 -3: h'f01400b089867804b8e9fc96c3932161f1934f4223069170d 1777 924b7e03bf822bb' 1778 } 1779 } 1780 } 1781 ] 1782 } 1784 C.5. Single Signature 1786 This example has some features that are in questions but not yet 1787 cooperated in the document. 1789 To make it easier to read, this uses CBOR's diagnostic notation 1790 rather than a binary dump. 1792 { 1793 1: 1, 1794 4: h'546869732069732074686520636f6e74656e742e', 1795 5: [ 1796 { 1797 2: h'a20165505333383405781e62696c626f2e62616767696e7340686f 1798 626269746f6e2e6578616d706c65', 1799 6: h'7c4656acc11ffe98e2ea4babff6d177b2e5a088da2034e0096a6f8 1800 8cd50a36ed971a83f42244d40d97043d080f43dff7a7c0eb5bc322a3d3d18826c 1801 e755d82293ecc22a3919857bc60c456017ca87b7d662971687aac7315f68c9f52 1802 d95c24f72418b7eb07cd432875ab42658bde269534da10d8572c2d5340be660cf 1803 cf7f6cceaf5cd02ddfdac1cf18930199c0e8721c2d71c646516cc3da79f6d555e 1804 89825803ef1ecf7fb411cea24d15610f56d33af0d1a7e68a2e07e9790326f01f2 1805 9ad7210e317c637f7cbd16f8cd32a9959dfd419de697dfa3145aa7cd1019072f9 1806 5c3d041bd8d47de09abbce16117733378e1593fe2439454cd907f88aabc664d26 1807 298' 1808 } 1809 ] 1810 } 1812 C.6. Multiple Signers 1814 This example has some features that are in questions but not yet 1815 cooperated in the document. 1817 To make it easier to read, this uses CBOR's diagnostic notation 1818 rather than a binary dump. 1820 Encoded in CBOR - 491 bytes, content is 14 bytes long 1821 { 1822 1: 1, 1823 4: h'546869732069732074686520636f6e74656e742e', 1824 5: [ 1825 { 1826 2: h'a10129', 1827 3: { 1828 5: "bilbo.baggins@hobbiton.example" 1829 }, 1830 6: h'93f83aaf872d9fc8c7cad30437dc8fed33a673ec5d4d8e004f16d9 1831 ed236f6b2ce4cc15ea48aef8c5c0c4eab8ed539a4eae27ac9d5f5e6ef7b9cfb02 1832 133f3f4ad7062db989fcff6ecc67c13624418224416116ff0a67d1a133d27bb79 1833 1a1893a03c683d84def6742059c63670c2738efc2dde8eac364b4d714c60db424 1834 ffbfb098c579c6538daa2a9fc5be2d829a82c148c9913a537f98ceb469b78fae2 1835 02531353fe740ba5ef3eb01377b01e7b27f0ffad35cdd3ef8d2c010a60331b2ac 1836 2924183022425a1a3a4495adb03d67a92fb420bd408cb0c81d5bac694d1568f11 1837 2ec8bbab834ca02b098c3b8f4975d75114bb001408252875d14bc1516f843b9fa 1838 bb0' 1839 }, 1840 { 1841 3: { 1842 1: -9, 1843 5: "bilbo.baggins@hobbiton.example" 1844 }, 1845 6: h'5bacf5cf8e84051f01030a688c9c5dfa867173a6038e6655374ce3 1846 e07de671d16dbe8cee3e965f2492d7850debf63b64a93e8fe7062ea536f3f165a 1847 e34d5852f5001f1a1caffc52b05aec184da5a4148e305d87d0ef68642701b05c6 1848 dde19669a1ffb39158a8fa4d51e95a2557b86da7a64a719a1422568dec9ec699d 1849 af93a58eab268' 1850 } 1851 ] 1852 } 1854 Appendix D. COSE Header Algorithm Label Table 1855 +------+-------------------+-------+----------+---------------------+ 1856 | name | algorithm | label | CBOR | description | 1857 | | | | type | | 1858 +------+-------------------+-------+----------+---------------------+ 1859 | apu | ECDH | -1 | bstr | | 1860 | | | | | | 1861 | apv | ECDH | -2 | bstr | | 1862 | | | | | | 1863 | epk | ECDH | -3 | COSE_Key | contains a COSE key | 1864 | | | | | not a JWK key | 1865 | | | | | | 1866 | iv | A128GCMKW, | -1 | bstr | | 1867 | | A192GCMKW, | | | | 1868 | | A256GCMKW | | | | 1869 | | | | | | 1870 | iv | A128GCM, A192GCM, | -1 | bstr | | 1871 | | A256GCM | | | | 1872 | | | | | | 1873 | p2c | PBE | -1 | int | | 1874 | | | | | | 1875 | p2s | PBE | -2 | bstr | | 1876 +------+-------------------+-------+----------+---------------------+ 1878 Appendix E. COSE Algorithm Name Values 1880 This table contains all of the defined algorithms for COSE. 1882 +--------------------+-------+--------------------------------------+ 1883 | name | value | description | 1884 +--------------------+-------+--------------------------------------+ 1885 | HS256 | 4 | HMAC w/ SHA-256 | 1886 | | | | 1887 | HS384 | 5 | HMAC w/ SHA-384 | 1888 | | | | 1889 | HS512 | 6 | HMAC w/ SHA-512 | 1890 | | | | 1891 | RS256 | * | RSASSA-v1.5 w/ SHA-256 | 1892 | | | | 1893 | RS384 | * | RSASSA-v1.5 w/ SHA-384 | 1894 | | | | 1895 | RSA512 | * | RSASSA-v1.5 w/ SHA-256 | 1896 | | | | 1897 | ES256 | -7 | ECDSA w/ SHA-256 | 1898 | | | | 1899 | ES384 | -8 | ECDSA w/ SHA-384 | 1900 | | | | 1901 | ES512 | -9 | ECDSA w/ SHA-512 | 1902 | | | | 1903 | PS256 | -10 | RSASSA-PSS w/ SHA-256 | 1904 | | | | 1905 | PS384 | * | RSASSA-PSS w/ SHA-384 | 1906 | | | | 1907 | PS512 | -11 | RSASSA-PSS w/ SHA-512 | 1908 | | | | 1909 | RSA1_5 | * | RSAES v1.5 Key Encryption | 1910 | | | | 1911 | RSA-OAEP | -2 | RSAES OAEP w/ SHA-256 | 1912 | | | | 1913 | A128KW | -3 | AES Key Wrap w/ 128-bit key | 1914 | | | | 1915 | A192KW | -4 | AES Key Wrap w/ 192-bit key | 1916 | | | | 1917 | A256KW | -5 | AES Key Wrap w/ 256-bit key | 1918 | | | | 1919 | dir | -6 | Direct use of CEK | 1920 | | | | 1921 | ECDH-ES | * | ECDH ES w/ Concat KDF as CEK | 1922 | | | | 1923 | ECDH-ES+A128KW | * | ECDH ES w/ Concat KDF and AES Key | 1924 | | | wrap w/ 128 bit key | 1925 | | | | 1926 | ECDH-ES+A192KW | * | ECDH ES w/ Concat KDF and AES Key | 1927 | | | wrap w/ 192 bit key | 1928 | | | | 1929 | ECDH-ES+A256KW | * | ECDH ES w/ Concat KDF and AES Key | 1930 | | | wrap w/ 256 bit key | 1931 | | | | 1932 | A128GCMKW | * | AES GCM Key Wrap w/ 128 bit key | 1933 | | | | 1934 | A192GCMKW | * | AES GCM Key Wrap w/ 192 bit key | 1935 | | | | 1936 | A256GCMKW | * | AES GCM Key Wrap w/ 256 bit key | 1937 | | | | 1938 | PBES2-HS256+A128KW | * | PBES2 w/ HMAC SHA-256 and AES Key | 1939 | | | wrap w/ 128 bit key | 1940 | | | | 1941 | PBES2-HS384+A192KW | * | PBES2 w/ HMAC SHA-384 and AES Key | 1942 | | | wrap w/ 192 bit key | 1943 | | | | 1944 | PBES2-HS512+A256KW | * | PBES2 w/ HMAC SHA-512 and AES Key | 1945 | | | wrap w/ 256 bit key | 1946 | | | | 1947 | A128GCM | 1 | AES-GCM mode w/ 128-bit key | 1948 | | | | 1949 | A192GCM | 2 | AES-GCM mode w/ 192-bit key | 1950 | | | | 1951 | A256GCM | 3 | AES-GCM mode w/ 256-bit key | 1952 +--------------------+-------+--------------------------------------+ 1954 Appendix F. COSE General Values 1956 +------+--------+-------------------------+ 1957 | name | number | description | 1958 +------+--------+-------------------------+ 1959 | EC | 1 | Elliptic Curve key Type | 1960 | | | | 1961 | RSA | 2 | RSA Key type | 1962 | | | | 1963 | oct | 3 | Octet Key type | 1964 | | | | 1965 | P256 | 4 | EC Curve P256 (NIST) | 1966 | | | | 1967 | P521 | 5 | EC Curve P521 (NIST) | 1968 +------+--------+-------------------------+ 1970 Appendix G. COSE Key Map Labels 1972 This table contains a list of all of the parameters defined for keys 1973 that were defined by the JOSE document set. In the table is the data 1974 value type to be used for CBOR as well as the integer value that can 1975 be used as a replacement for the name in order to further decrease 1976 the size of the sent item. 1978 +----------+-------+-------+-------------+--------------------------+ 1979 | name | label | CBOR | registry | description | 1980 | | | type | | | 1981 +----------+-------+-------+-------------+--------------------------+ 1982 | kty | 1 | tstr | COSE | Identification of the | 1983 | | | / int | General | key type | 1984 | | | | Values | | 1985 | | | | | | 1986 | use | * | tstr | | deprecated - don't use | 1987 | | | | | | 1988 | key_ops | * | [* | | | 1989 | | | tstr] | | | 1990 | | | | | | 1991 | alg | 3 | tstr | COSE | Key usage restriction to | 1992 | | | / int | Algorithm | this algorithm | 1993 | | | | Values | | 1994 | | | | | | 1995 | kid | 2 | bstr | | Key Identification value | 1996 | | | | | - match to kid in | 1997 | | | | | message | 1998 | | | | | | 1999 | x5u | * | tstr | | | 2000 | | | | | | 2001 | x5c | * | bstr* | | | 2002 | | | | | | 2003 | x5t | * | bstr | | | 2004 | | | | | | 2005 | x5t#S256 | * | bstr | | | 2006 +----------+-------+-------+-------------+--------------------------+ 2008 ;key_keys 2009 kty=1 2010 key_kid=2 2011 key_alg=3 2013 Appendix H. COSE Key Parameter Labels 2015 This table contains a list of all of the parameters that were defined 2016 by the JOSE document set for a specific key type. In the table is 2017 the data value type to be used for CBOR as well as the integer value 2018 that can be used as a replacement for the name in order to further 2019 decrease the size of the sent item. Parameters dealing with keys 2020 +-------+------+-------+---------+--------------------+-------------+ 2021 | key | name | label | CBOR | registry | description | 2022 | type | | | type | | | 2023 +-------+------+-------+---------+--------------------+-------------+ 2024 | EC | crv | -1 | int / | Pull from general | | 2025 | | | | tstr | value registry | | 2026 | | | | | | | 2027 | EC | x | -2 | bstr | | | 2028 | | | | | | | 2029 | EC | y | -3 | bstr | | | 2030 | | | | | | | 2031 | EC | d | -4 | bstr | | | 2032 | | | | | | | 2033 | RSA | e | -1 | bstr | | | 2034 | | | | | | | 2035 | RSA | n | -2 | bstr | | | 2036 | | | | | | | 2037 | RSA | d | -3 | bstr | | | 2038 | | | | | | | 2039 | RSA | p | -4 | bstr | | | 2040 | | | | | | | 2041 | RSA | q | -5 | bstr | | | 2042 | | | | | | | 2043 | RSA | dp | -6 | bstr | | | 2044 | | | | | | | 2045 | RSA | dq | -7 | bstr | | | 2046 | | | | | | | 2047 | RSA | qi | -8 | bstr | | | 2048 | | | | | | | 2049 | RSA | oth | -9 | bstr | | | 2050 | | | | | | | 2051 | RSA | r | -10 | bstr | | | 2052 | | | | | | | 2053 | RSA | t | -11 | bstr | | | 2054 | | | | | | | 2055 | oct | k | -1 | bstr | | | 2056 +-------+------+-------+---------+--------------------+-------------+ 2058 Editorial Comments 2060 [CREF1] JLS: Need to check this list for correctness before publishing. 2062 [CREF2] JLS: I have moved msg_type into the individual structures. 2063 However, they would not be necessary in the cases where a) the 2064 security service is known and b) security libraries can setup to 2065 take individual structures. Should they be moved back to just 2066 appearing if used in a COSE_MSG rather than on the individual 2067 structure? 2069 [CREF3] JLS: Should we create an IANA registries for the values of 2070 msg_type? 2072 [CREF4] JLS: OPEN ISSUE 2074 [CREF5] JLS: A completest version of this grammar would list the options 2075 available in the protected and unprotected headers. Do we want 2076 to head that direction? 2078 [CREF6] JLS: Need to figure out how we are going to go about creating 2079 this registry -or are we going to modify the current mime- 2080 content table? 2082 [CREF7] Ilari: I don't follow/understand this text 2084 [CREF8] JLS: Finish the registration process. 2086 [CREF9] JLS: Should we register both or just the cose+cbor one? 2088 Author's Address 2090 Jim Schaad 2091 August Cellars 2093 Email: ietf@augustcellars.com