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'CMSECC') ** Downref: Normative reference to an Informational RFC: RFC 7748 (ref. 'CURVES') ** Downref: Normative reference to an Informational RFC: RFC 5869 (ref. 'HKDF') -- Possible downref: Non-RFC (?) normative reference: ref. 'ID.curdle-pkix' -- Possible downref: Non-RFC (?) normative reference: ref. 'SEC1' ** Obsolete normative reference: RFC 5751 (ref. 'SMIME') (Obsoleted by RFC 8551) -- Possible downref: Non-RFC (?) normative reference: ref. 'X680' -- Possible downref: Non-RFC (?) normative reference: ref. 'X690' Summary: 5 errors (**), 0 flaws (~~), 3 warnings (==), 10 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet-Draft R. Housley 3 Intended status: Standards Track Vigil Security 4 Expires: 4 December 2017 4 June 2017 6 Use of the Elliptic Curve Diffie-Hellman Key Agreement Algorithm 7 with X25519 and X448 in the Cryptographic Message Syntax (CMS) 9 11 Abstract 13 This document describes the conventions for using Elliptic Curve 14 Diffie-Hellman (ECDH) key agreement algorithm using curve25519 and 15 curve448 in the Cryptographic Message Syntax (CMS). 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on 4 December 2017. 34 Copyright Notice 36 Copyright (c) 2017 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 52 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 53 1.2. ASN.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Key Agreement . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2.1. ANSI-X9.63-KDF . . . . . . . . . . . . . . . . . . . . . . 5 56 2.2. HKDF . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 57 3. Enveloped-data Conventions . . . . . . . . . . . . . . . . . . 6 58 3.1. EnvelopedData Fields . . . . . . . . . . . . . . . . . . . 6 59 3.2. KeyAgreeRecipientInfo Fields . . . . . . . . . . . . . . . 7 60 4. Authenticated-data Conventions . . . . . . . . . . . . . . . . 8 61 4.1. AuthenticatedData Fields . . . . . . . . . . . . . . . . . 8 62 4.2. KeyAgreeRecipientInfo Fields . . . . . . . . . . . . . . . 8 63 5. Authenticated-Enveloped-data Conventions . . . . . . . . . . . 8 64 5.1. AuthEnvelopedData Fields . . . . . . . . . . . . . . . . . 9 65 5.2. KeyAgreeRecipientInfo Fields . . . . . . . . . . . . . . . 9 66 6. Certificate Conventions . . . . . . . . . . . . . . . . . . . 9 67 7. Key Agreement Algorithm Identifiers . . . . . . . . . . . . . 9 68 8. SMIMECapabilities Attribute Conventions . . . . . . . . . . . 10 69 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11 70 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 71 11. Normative References . . . . . . . . . . . . . . . . . . . . 12 72 12. Informative References . . . . . . . . . . . . . . . . . . . 14 73 Appendix: ASN.1 Module . . . . . . . . . . . . . . . . . . . . . . 15 74 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 17 75 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 17 77 1. Introduction 79 This document describes the conventions for using Elliptic Curve 80 Diffie-Hellman (ECDH) key agreement using curve25519 and curve448 81 [CURVES] in the Cryptographic Message Syntax (CMS) [CMS]. Key 82 agreement is supported in three CMS content types: the enveloped-data 83 content type [CMS], authenticated-data content type [CMS], and the 84 authenticated-enveloped-data content type [AUTHENV]. 86 The conventions for using some Elliptic Curve Cryptography (ECC) 87 algorithms in CMS are described in [CMSECC]. These conventions cover 88 the use of ECDH with some curves other than curve25519 and curve448 89 [CURVES]. Those other curves are not deprecated. 91 Using curve25519 with Diffie-Hellman key agreement is referred to as 92 X25519. Using curve448 with Diffie-Hellman key agreement is referred 93 to as X448. 95 1.1. Terminology 97 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 98 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 99 document are to be interpreted as described in RFC 2119 [STDWORDS]. 101 1.2. ASN.1 103 CMS values are generated using ASN.1 [X680], which uses the Basic 104 Encoding Rules (BER) and the Distinguished Encoding Rules (DER) 105 [X690]. 107 2. Key Agreement 109 In 1976, Diffie and Hellman described a means for two parties to 110 agree upon a shared secret value in manner that prevents 111 eavesdroppers from learning the shared secret value [DH1976]. This 112 secret may then be converted into pairwise symmetric keying material 113 for use with other cryptographic algorithms. Over the years, many 114 variants of this fundamental technique have been developed. This 115 document describes the conventions for using Ephemeral-Static 116 Elliptic Curve Diffie-Hellman (ECDH) key agreement using X25519 and 117 X448 [CURVES]. 119 The originator MUST use an ephemeral public/private key pair that is 120 generated on the same elliptic curve as the public key of the 121 recipient. The ephemeral key pair MUST be used for a single CMS 122 protected content type, and then it MUST be discarded. The 123 originator obtains the recipient's static public key from the 124 recipient's certificate [PROFILE]. 126 X25519 is described in Section 6.1 of [CURVES], and X448 is described 127 in Section 6.2 of [CURVES]. Conforming implementations MUST check 128 whether the computed Diffie-Hellman shared secret is the all-zero 129 value, and abort if so, as described in Section 6 of [CURVES]. If an 130 alternative implementation of these elliptic curves to that 131 documented in Section 6 of [CURVES] is employed, then the additional 132 checks specified in Section 7 of [CURVES] SHOULD be performed. 134 In [CURVES], the shared secret value that is produced by ECDH is 135 called K. (In some other specifications, the shared secret value is 136 called Z.) A key derivation function (KDF) is used to produce a 137 pairwise key-encryption key (KEK) from the shared secret value (K), 138 the length of the key-encryption key, and the DER-encoded ECC-CMS- 139 SharedInfo structure [CMSECC]. 141 The ECC-CMS-SharedInfo definition from [CMSECC] is repeated here for 142 convenience. 144 ECC-CMS-SharedInfo ::= SEQUENCE { 145 keyInfo AlgorithmIdentifier, 146 entityUInfo [0] EXPLICIT OCTET STRING OPTIONAL, 147 suppPubInfo [2] EXPLICIT OCTET STRING } 149 The ECC-CMS-SharedInfo keyInfo field contains the object identifier 150 of the key-encryption algorithm and associated parameters. This 151 algorithm will be used to wrap the content-encryption key. For 152 example, the AES Key Wrap algorithm [AESKW] does not need parameters, 153 so the algorithm identifier parameters are absent. 155 The ECC-CMS-SharedInfo entityUInfo field optionally contains 156 additional keying material supplied by the sending agent. Note that 157 [CMS] requires implementations to accept a KeyAgreeRecipientInfo 158 SEQUENCE that includes the ukm field. If the ukm field is present, 159 the ukm is placed in the entityUInfo field. By including the ukm, a 160 different key-encryption key is generated even when the originator 161 ephemeral private key is improperly used more than once. Therefore, 162 if the ukm field is present, it MUST be selected in a manner that 163 provides with very high probability a unique value; however, there is 164 no security benefit to using a ukm value that is longer than the key- 165 encryption key that will be produced by the KDF. 167 The ECC-CMS-SharedInfo suppPubInfo field contains the length of the 168 generated key-encryption key, in bits, represented as a 32-bit number 169 in network byte order. For example, the key length for AES-256 [AES] 170 would be 0x00000100. 172 2.1. ANSI-X9.63-KDF 174 The ANSI-X9.63-KDF key derivation function is a simple construct 175 based on a one-way hash function described in American National 176 Standard X9.63 [X963]. This KDF is also described in Section 3.6.1 177 of [SEC1]. 179 Three values are concatenated to produce the input string to the KDF: 180 1. The shared secret value generated by ECDH, K. 181 2. The iteration counter, starting with one, as described below. 182 3. The DER-encoded ECC-CMS-SharedInfo structure. 184 To generate a key-encryption key (KEK), the KDF generates one or more 185 KM blocks, with the counter starting at 0x00000001, and incrementing 186 the counter for each subsequent KM block until enough material has 187 been generated. The 32-bit counter is represented in network byte 188 order. The KM blocks are concatenated left to right, and then the 189 leftmost portion of the result is used as the pairwise key-encryption 190 key, KEK: 192 KM(i) = Hash(K || INT32(counter=i) || DER(ECC-CMS-SharedInfo)) 194 KEK = KM(counter=1) || KM(counter=2) ... 196 2.2. HKDF 198 The HMAC-based Extract-and-Expand Key Derivation Function (HKDF) is a 199 robust construct based on a one-way hash function described in RFC 200 5869 [HKDF]. HKDF is comprised of two steps: HKDF-Extract followed 201 by HKDF-Expand. 203 Three values are used as inputs to the HKDF: 204 1. The shared secret value generated by ECDH, K. 205 2. The length in octets of the keying data to be generated. 206 3. The DER-encoded ECC-CMS-SharedInfo structure. 208 The ECC-CMS-SharedInfo structure optionally includes the ukm. If the 209 ukm is present, the ukm is also used as the HKDF salt. HKDF uses an 210 appropriate number of zero octets when no salt is provided. 212 The length of the generated key-encryption key is used in two places, 213 once in bits, and once in octets. The ECC-CMS-SharedInfo structure 214 includes the length of the generated key-encryption key in bits. The 215 HKDF-Expand function takes an argument for the length of the 216 generated key-encryption key in octets. 218 In summary, to produce the pairwise key-encryption key, KEK: 220 if ukm is provided, then salt = ukm, else salt is not provided 221 PRK = HKDF-Extract(salt, K) 223 KEK = HKDF-Expand(PRK, DER(ECC-CMS-SharedInfo), SizeInOctets(KEK)) 225 3. Enveloped-data Conventions 227 The CMS enveloped-data content type [CMS] consists of an encrypted 228 content and wrapped content-encryption keys for one or more 229 recipients. The ECDH key agreement algorithm is used to generate a 230 pairwise key-encryption key between the originator and a particular 231 recipient. Then, the key-encryption key is used to wrap the content- 232 encryption key for that recipient. When there is more than one 233 recipient, the same content-encryption key MUST be wrapped for each 234 of them. 236 A compliant implementation MUST meet the requirements for 237 constructing an enveloped-data content type in Section 6 of [CMS]. 239 A content-encryption key MUST be randomly generated for each instance 240 of an enveloped-data content type. The content-encryption key is 241 used to encrypt the content. 243 3.1. EnvelopedData Fields 245 The enveloped-data content type is ASN.1 encoded using the 246 EnvelopedData syntax. The fields of the EnvelopedData syntax MUST be 247 populated as described in Section 6 of [CMS]. The RecipientInfo 248 choice is described in Section 6.2 of [CMS], and repeated here for 249 convenience. 251 RecipientInfo ::= CHOICE { 252 ktri KeyTransRecipientInfo, 253 kari [1] KeyAgreeRecipientInfo, 254 kekri [2] KEKRecipientInfo, 255 pwri [3] PasswordRecipientinfo, 256 ori [4] OtherRecipientInfo } 258 For the recipients that use X25519 or X448 the RecipientInfo kari 259 choice MUST be used. 261 3.2. KeyAgreeRecipientInfo Fields 263 The fields of the KeyAgreeRecipientInfo syntax MUST be populated as 264 described in this section when X25519 or X448 is employed for one or 265 more recipients. 267 The KeyAgreeRecipientInfo version MUST be 3. 269 The KeyAgreeRecipientInfo originator provides three alternatives for 270 identifying the originator's public key, and the originatorKey 271 alternative MUST be used. The originatorKey MUST contain an 272 ephemeral key for the originator. The originatorKey algorithm field 273 MUST contain the id-X25519 or the id-X448 object identifier. The 274 originator's ephemeral public key MUST be encoded as an OCTET STRING. 276 The object identifiers for X25519 and X448 have been assigned in 277 [ID.curdle-pkix]. They are repeated below for convenience. 279 When using X25519, the public key contains exactly 32 octets, and the 280 id-X25519 object identifier is used: 282 id-X25519 OBJECT IDENTIFIER ::= { 1 3 101 110 } 284 When using X448, the public key contains exactly 56 octets, and the 285 id-X448 object identifier is used: 287 id-X448 OBJECT IDENTIFIER ::= { 1 3 101 111 } 289 KeyAgreeRecipientInfo ukm is optional. The processing of the ukm 290 with The ANSI-X9.63-KDF key derivation function is described in 291 Section 2.1, and the processing of the ukm with the HKDF key 292 derivation function is described in Section 2.2. 294 KeyAgreeRecipientInfo keyEncryptionAlgorithm MUST contain the object 295 identifier of the key-encryption algorithm that will be used to wrap 296 the content-encryption key. The conventions for using AES-128, 297 AES-192, and AES-256 in the key wrap mode are specified in [CMSAES]. 299 KeyAgreeRecipientInfo recipientEncryptedKeys includes a recipient 300 identifier and encrypted key for one or more recipients. The 301 RecipientEncryptedKey KeyAgreeRecipientIdentifier MUST contain either 302 the issuerAndSerialNumber identifying the recipient's certificate or 303 the RecipientKeyIdentifier containing the subject key identifier from 304 the recipient's certificate. In both cases, the recipient's 305 certificate contains the recipient's static X25519 or X448 public 306 key. RecipientEncryptedKey EncryptedKey MUST contain the content- 307 encryption key encrypted with the pairwise key-encryption key using 308 the algorithm specified by the KeyWrapAlgorithm. 310 4. Authenticated-data Conventions 312 The CMS authenticated-data content type [CMS] consists an 313 authenticated content, a message authentication code (MAC), and 314 encrypted authentication keys for one or more recipients. The ECDH 315 key agreement algorithm is used to generate a pairwise key-encryption 316 key between the originator and a particular recipient. Then, the 317 key-encryption key is used to wrap the authentication key for that 318 recipient. When there is more than one recipient, the same 319 authentication key MUST be wrapped for each of them. 321 A compliant implementation MUST meet the requirements for 322 constructing an authenticated-data content type in Section 9 of 323 [CMS]. 325 A authentication key MUST be randomly generated for each instance of 326 an authenticated-data content type. The authentication key is used 327 to compute the MAC over the content. 329 4.1. AuthenticatedData Fields 331 The authenticated-data content type is ASN.1 encoded using the 332 AuthenticatedData syntax. The fields of the AuthenticatedData syntax 333 MUST be populated as described in [CMS]; for the recipients that use 334 X25519 or X448 the RecipientInfo kari choice MUST be used. 336 4.2. KeyAgreeRecipientInfo Fields 338 The fields of the KeyAgreeRecipientInfo syntax MUST be populated as 339 described in Section 3.2 of this document. 341 5. Authenticated-Enveloped-data Conventions 343 The CMS authenticated-enveloped-data content type [AUTHENV] consists 344 of an authenticated and encrypted content and encrypted content- 345 authenticated-encryption keys for one or more recipients. The ECDH 346 key agreement algorithm is used to generate a pairwise key-encryption 347 key between the originator and a particular recipient. Then, the 348 key-encryption key is used to wrap the content-authenticated- 349 encryption key for that recipient. When there is more than one 350 recipient, the same content-authenticated-encryption key MUST be 351 wrapped for each of them. 353 A compliant implementation MUST meet the requirements for 354 constructing an authenticated-data content type in Section 2 of 355 [AUTHENV]. 357 A content-authenticated-encryption key MUST be randomly generated for 358 each instance of an authenticated-enveloped-data content type. The 359 content-authenticated-encryption key is used to authenticate and 360 encrypt the content. 362 5.1. AuthEnvelopedData Fields 364 The authenticated-enveloped-data content type is ASN.1 encoded using 365 the AuthEnvelopedData syntax. The fields of the AuthEnvelopedData 366 syntax MUST be populated as described in [AUTHENV]; for the 367 recipients that use X25519 or X448 the RecipientInfo kari choice MUST 368 be used. 370 5.2. KeyAgreeRecipientInfo Fields 372 The fields of the KeyAgreeRecipientInfo syntax MUST be populated as 373 described in Section 3.2 of this document. 375 6. Certificate Conventions 377 RFC 5280 [PROFILE] specifies the profile for using X.509 Certificates 378 in Internet applications. A recipient static public key is needed 379 for X25519 or X448, and the originator obtains that public key from 380 the recipient's certificate. The conventions for carrying X25519 and 381 X448 public keys are specified in [ID.curdle-pkix]. 383 7. Key Agreement Algorithm Identifiers 385 The following object identifiers are assigned in [CMSECC] to indicate 386 ECDH with ANSI-X9.63-KDF using various one-way hash functions. These 387 are expected to be used as AlgorithmIdentifiers with a parameter that 388 specifies the key-encryption algorithm. These are repeated here for 389 convenience. 391 secg-scheme OBJECT IDENTIFIER ::= { 392 iso(1) identified-organization(3) certicom(132) schemes(1) } 394 dhSinglePass-stdDH-sha256kdf-scheme OBJECT IDENTIFIER ::= { 395 secg-scheme 11 1 } 397 dhSinglePass-stdDH-sha384kdf-scheme OBJECT IDENTIFIER ::= { 398 secg-scheme 11 2 } 400 dhSinglePass-stdDH-sha512kdf-scheme OBJECT IDENTIFIER ::= { 401 secg-scheme 11 3 } 403 The following object identifiers are assigned to indicate ECDH with 404 HKDF using various one-way hash functions. These are expected to be 405 used as AlgorithmIdentifiers with a parameter that specifies the 406 key-encryption algorithm. 408 smime-alg OBJECT IDENTIFIER ::= { 409 iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 410 pkcs-9(9) smime(16) alg(3) } 412 dhSinglePass-stdDH-hkdf-sha256-scheme OBJECT IDENTIFIER ::= { 413 smime-alg TBD1 } 415 dhSinglePass-stdDH-hkdf-sha384-scheme OBJECT IDENTIFIER ::= { 416 smime-alg TBD2 } 418 dhSinglePass-stdDH-hkdf-sha512-scheme OBJECT IDENTIFIER ::= { 419 smime-alg TBD3 } 421 8. SMIMECapabilities Attribute Conventions 423 A sending agent MAY announce to other agents that it supports ECDH 424 key agreement using the SMIMECapabilities signed attribute in a 425 signed message [SMIME] or a certificate [CERTCAP]. Following the 426 pattern established in [CMSECC], the SMIMECapabilities associated 427 with ECDH carries a DER-encoded object identifier that identifies 428 support for ECDH in conjunction with a particular KDF, and it 429 includes a parameter that names the key wrap algorithm. 431 The following SMIMECapabilities values (in hexidecimal) from [CMSECC] 432 might be of interest to implementations that support X25519 and X448: 434 ECDH with ANSI-X9.63-KDF using SHA-256; uses AES-128 key wrap: 435 30 15 06 06 2B 81 04 01 0B 01 30 0B 06 09 60 86 48 01 65 03 04 436 01 05 438 ECDH with ANSI-X9.63-KDF using SHA-384; uses AES-128 key wrap: 439 30 15 06 06 2B 81 04 01 0B 02 30 0B 06 09 60 86 48 01 65 03 04 440 01 05 442 ECDH with ANSI-X9.63-KDF using SHA-512; uses AES-128 key wrap: 443 30 15 06 06 2B 81 04 01 0B 03 30 0B 06 09 60 86 48 01 65 03 04 444 01 05 446 ECDH with ANSI-X9.63-KDF using SHA-256; uses AES-256 key wrap: 447 30 15 06 06 2B 81 04 01 0B 01 30 0B 06 09 60 86 48 01 65 03 04 448 01 2D 450 ECDH with ANSI-X9.63-KDF using SHA-384; uses AES-256 key wrap: 451 30 15 06 06 2B 81 04 01 0B 02 30 0B 06 09 60 86 48 01 65 03 04 452 01 2D 454 ECDH with ANSI-X9.63-KDF using SHA-512; uses AES-256 key wrap: 455 30 15 06 06 2B 81 04 01 0B 03 30 0B 06 09 60 86 48 01 65 03 04 456 01 2D 458 The following SMIMECapabilities values (in hexidecimal) based on the 459 algorithm identifiers in Section 7 of this document might be of 460 interest to implementations that support X25519 and X448: 462 ECDH with HKDF using SHA-256; uses AES-128 key wrap: 463 TBD 465 ECDH with HKDF using SHA-384; uses AES-128 key wrap: 466 TBD 468 ECDH with HKDF using SHA-512; uses AES-128 key wrap: 469 TBD 471 ECDH with HKDF using SHA-256; uses AES-256 key wrap: 472 TBD 474 ECDH with HKDF using SHA-384; uses AES-256 key wrap: 475 TBD 477 ECDH with HKDF using SHA-512; uses AES-256 key wrap: 478 TBD 480 9. Security Considerations 482 Please consult the security considerations of [CMS] for security 483 considerations related to the enveloped-data content type and the 484 authenticated-data content type. 486 Please consult the security considerations of [AUTHENV] for security 487 considerations related to the authenticated-enveloped-data content 488 type. 490 Please consult the security considerations of [CURVES] for security 491 considerations related to the use of X25519 and X448. 493 The originator uses an ephemeral public/private key pair that is 494 generated on the same elliptic curve as the public key of the 495 recipient. The ephemeral key pair is used for a single CMS protected 496 content type, and then it is discarded. If the originator wants to 497 be able to decrypt the content (for enveloped-data and authenticated- 498 enveloped-data) or check the authentication (for authenticated-data), 499 then the originator needs to treat themselves as a recipient. 501 As specified in [CMS], implementations MUST support processing of the 502 KeyAgreeRecipientInfo ukm field; this ensures that interoperability 503 is not a concern whether the ukm is present or absent. The ukm is 504 placed in the entityUInfo field of the ECC-CMS-SharedInfo structure. 505 When present, the ukm ensures that a different key-encryption key is 506 generated, even when the originator ephemeral private key is 507 improperly used more than once. 509 10. IANA Considerations 511 One object identifier for the ASN.1 module in the Appendix needs to 512 be assigned in the SMI Security for S/MIME Module Identifiers 513 (1.2.840.113549.1.9.16.0) [IANA-MOD] registry: 515 id-mod-cms-ecdh-alg-2017 OBJECT IDENTIFIER ::= { 516 iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 517 pkcs-9(9) smime(16) mod(0) TBD0 } 519 Three object identifiers for the Key Agreement Algorithm Identifiers 520 in Sections 7 need to be assigned in the SMI Security for S/MIME 521 Algorithms (1.2.840.113549.1.9.16.3) [IANA-ALG] registry: 523 smime-alg OBJECT IDENTIFIER ::= { 524 iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 525 pkcs-9(9) smime(16) alg(3) } 527 dhSinglePass-stdDH-hkdf-sha256-scheme OBJECT IDENTIFIER ::= { 528 smime-alg TBD1 } 530 dhSinglePass-stdDH-hkdf-sha384-scheme OBJECT IDENTIFIER ::= { 531 smime-alg TBD2 } 533 dhSinglePass-stdDH-hkdf-sha512-scheme OBJECT IDENTIFIER ::= { 534 smime-alg TBD3 } 536 11. Normative References 538 [AUTHENV] Housley, R., "Cryptographic Message Syntax (CMS) 539 Authenticated-Enveloped-Data Content Type", RFC 5083, 540 November 2007. 542 [CERTCAP] Santesson, S., "X.509 Certificate Extension for 543 Secure/Multipurpose Internet Mail Extensions (S/MIME) 544 Capabilities", RFC 4262, December 2005. 546 [CMS] Housley, R., "Cryptographic Message Syntax (CMS)", RFC 547 5652, September 2009. 549 [CMSASN1] Hoffman, P., and J. Schaad, "New ASN.1 Modules for 550 Cryptographic Message Syntax (CMS) and S/MIME", RFC 5911, 551 June 2010. 553 [CMSECC] Turner, S., and D. Brown, "Use of Elliptic Curve 554 Cryptography (ECC) Algorithms in Cryptographic Message 555 Syntax (CMS)", RFC 5753, January 2010. 557 [CURVES] Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves 558 for Security", RFC 7748, January 2016. 560 [HKDF] Krawczyk, H., and P. Eronen, "HMAC-based Extract-and- 561 Expand Key Derivation Function (HKDF)", RFC 5869, May 562 2010. 564 [ID.curdle-pkix] 565 Josefsson, S., and J. Schaad, "Algorithm Identifiers for 566 Ed25519, Ed25519ph, Ed448, Ed448ph, X25519 and X448 for 567 use in the Internet X.509 Public Key Infrastructure", 568 15 August 2016, Work-in-progress. 570 [PKIXALG] Bassham, L., Polk, W., and R. Housley, "Algorithms and 571 Identifiers for the Internet X.509 Public Key 572 Infrastructure Certificate and Certificate Revocation List 573 (CRL) Profile", RFC 3279, April 2002. 575 [PKIXECC] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk, 576 "Elliptic Curve Cryptography Subject Public Key 577 Information", RFC 5480, March 2009. 579 [PROFILE] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 580 Housley, R., and W. Polk, "Internet X.509 Public Key 581 Infrastructure Certificate and Certificate Revocation List 582 (CRL) Profile", RFC 5280, May 2008. 584 [SEC1] Standards for Efficient Cryptography Group, "SEC 1: 585 Elliptic Curve Cryptography", version 2.0, May 2009, 586 . 588 [SMIME] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet 589 Mail Extensions (S/MIME) Version 3.2 Message 590 Specification", RFC 5751, January 2010. 592 [STDWORDS] Bradner, S., "Key words for use in RFCs to Indicate 593 Requirement Levels", BCP 14, RFC 2119, March 1997. 595 [X680] ITU-T, "Information technology -- Abstract Syntax Notation 596 One (ASN.1): Specification of basic notation", ITU-T 597 Recommendation X.680, 2015. 599 [X690] ITU-T, "Information technology -- ASN.1 encoding rules: 600 Specification of Basic Encoding Rules (BER), Canonical 601 Encoding Rules (CER) and Distinguished Encoding Rules 602 (DER)", ITU-T Recommendation X.690, 2015. 604 12. Informative References 606 [AES] National Institute of Standards and Technology. FIPS Pub 607 197: Advanced Encryption Standard (AES). 26 November 2001. 609 [AESKW] Schaad, J., and R. Housley, "Advanced Encryption Standard 610 (AES) Key Wrap Algorithm", RFC 3394, September 2002. 612 [CMSAES] Schaad, J., "Use of the Advanced Encryption Standard (AES) 613 Encryption Algorithm in Cryptographic Message Syntax 614 (CMS)", RFC 3565, July 2003. 616 [DH1976] Diffie, W., and M. E. Hellman, "New Directions in 617 Cryptography", IEEE Trans. on Info. Theory, Vol. IT-22, 618 Nov. 1976, pp. 644-654. 620 [IANA-ALG] https://www.iana.org/assignments/smi-numbers/ 621 smi-numbers.xhtml#security-smime-3. 623 [IANA-MOD] https://www.iana.org/assignments/smi-numbers/ 624 smi-numbers.xhtml#security-smime-0. 626 [X963] "Public-Key Cryptography for the Financial Services 627 Industry: Key Agreement and Key Transport Using Elliptic 628 Curve Cryptography", American National Standard 629 X9.63-2001, 2001. 631 Appendix: ASN.1 Module 633 CMSECDHAlgs-2017 634 { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9) 635 smime(16) modules(0) id-mod-cms-ecdh-alg-2017(TBD0) } 637 DEFINITIONS IMPLICIT TAGS ::= 638 BEGIN 640 -- EXPORTS ALL 642 IMPORTS 644 KeyWrapAlgorithm 645 FROM CryptographicMessageSyntaxAlgorithms-2009 -- in [CMSASN1] 646 { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 647 pkcs-9(9) smime(16) modules(0) id-mod-cmsalg-2001-02(37) } 649 KEY-AGREE, SMIME-CAPS 650 FROM AlgorithmInformation-2009 -- in [CMSASN1] 651 { iso(1) identified-organization(3) dod(6) internet(1) 652 security(5) mechanisms(5) pkix(7) id-mod(0) 653 id-mod-algorithmInformation-02(58) } 655 dhSinglePass-stdDH-sha256kdf-scheme, 656 dhSinglePass-stdDH-sha384kdf-scheme, 657 dhSinglePass-stdDH-sha512kdf-scheme, 658 kaa-dhSinglePass-stdDH-sha256kdf-scheme, 659 kaa-dhSinglePass-stdDH-sha384kdf-scheme, 660 kaa-dhSinglePass-stdDH-sha512kdf-scheme, 661 cap-kaa-dhSinglePass-stdDH-sha256kdf-scheme, 662 cap-kaa-dhSinglePass-stdDH-sha384kdf-scheme, 663 cap-kaa-dhSinglePass-stdDH-sha512kdf-scheme 664 FROM CMSECCAlgs-2009-02 -- in [CMSECC] 665 { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 666 pkcs-9(9) smime(16) modules(0) 667 id-mod-cms-ecc-alg-2009-02(46) } 668 ; 670 -- 671 -- Object Identifiers 672 -- 674 smime-alg OBJECT IDENTIFIER ::= { 675 iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 676 pkcs-9(9) smime(16) alg(3) } 678 dhSinglePass-stdDH-hkdf-sha256-scheme OBJECT IDENTIFIER ::= { 679 smime-alg TBD1 } 681 dhSinglePass-stdDH-hkdf-sha384-scheme OBJECT IDENTIFIER ::= { 682 smime-alg TBD2 } 684 dhSinglePass-stdDH-hkdf-sha512-scheme OBJECT IDENTIFIER ::= { 685 smime-alg TBD3 } 687 -- 688 -- Extend the Key Agreement Algorithms in [CMSECC] 689 -- 691 KeyAgreementAlgs KEY-AGREE ::= { ..., 692 kaa-dhSinglePass-stdDH-sha256kdf-scheme | 693 kaa-dhSinglePass-stdDH-sha384kdf-scheme | 694 kaa-dhSinglePass-stdDH-sha512kdf-scheme | 695 kaa-dhSinglePass-stdDH-hkdf-sha256-scheme | 696 kaa-dhSinglePass-stdDH-hkdf-sha384-scheme | 697 kaa-dhSinglePass-stdDH-hkdf-sha512-scheme } 699 kaa-dhSinglePass-stdDH-hkdf-sha256-scheme KEY-AGREE ::= { 700 IDENTIFIER dhSinglePass-stdDH-hkdf-sha256-scheme 701 PARAMS TYPE KeyWrapAlgorithm ARE required 702 UKM -- TYPE unencoded data -- ARE preferredPresent 703 SMIME-CAPS cap-kaa-dhSinglePass-stdDH-hkdf-sha256-scheme } 705 kaa-dhSinglePass-stdDH-hkdf-sha384-scheme KEY-AGREE ::= { 706 IDENTIFIER dhSinglePass-stdDH-hkdf-sha384-scheme 707 PARAMS TYPE KeyWrapAlgorithm ARE required 708 UKM -- TYPE unencoded data -- ARE preferredPresent 709 SMIME-CAPS cap-kaa-dhSinglePass-stdDH-hkdf-sha384-scheme } 711 kaa-dhSinglePass-stdDH-hkdf-sha512-scheme KEY-AGREE ::= { 712 IDENTIFIER dhSinglePass-stdDH-hkdf-sha512-scheme 713 PARAMS TYPE KeyWrapAlgorithm ARE required 714 UKM -- TYPE unencoded data -- ARE preferredPresent 715 SMIME-CAPS cap-kaa-dhSinglePass-stdDH-hkdf-sha512-scheme } 717 -- 718 -- Extend the S/MIME CAPS in [CMSECC] 719 -- 721 SMimeCAPS SMIME-CAPS ::= { ..., 722 kaa-dhSinglePass-stdDH-sha256kdf-scheme.&smimeCaps | 723 kaa-dhSinglePass-stdDH-sha384kdf-scheme.&smimeCaps | 724 kaa-dhSinglePass-stdDH-sha512kdf-scheme.&smimeCaps | 725 kaa-dhSinglePass-stdDH-hkdf-sha256-scheme.&smimeCaps | 726 kaa-dhSinglePass-stdDH-hkdf-sha384-scheme.&smimeCaps | 727 kaa-dhSinglePass-stdDH-hkdf-sha512-scheme.&smimeCaps } 729 cap-kaa-dhSinglePass-stdDH-hkdf-sha256-scheme SMIME-CAPS ::= { 730 TYPE KeyWrapAlgorithm 731 IDENTIFIED BY dhSinglePass-stdDH-hkdf-sha256-scheme } 733 cap-kaa-dhSinglePass-stdDH-hkdf-sha384-scheme SMIME-CAPS ::= { 734 TYPE KeyWrapAlgorithm 735 IDENTIFIED BY dhSinglePass-stdDH-hkdf-sha384-scheme} 737 cap-kaa-dhSinglePass-stdDH-hkdf-sha512-scheme SMIME-CAPS ::= { 738 TYPE KeyWrapAlgorithm 739 IDENTIFIED BY dhSinglePass-stdDH-hkdf-sha512-scheme } 741 END 743 Acknowledgements 745 Many thanks to Roni Even, Daniel Migault, Eric Rescorla, Jim Schaad, 746 Stefan Santesson, and Sean Turner for their review and insightful 747 suggestions. 749 Author's Address 751 Russ Housley 752 918 Spring Knoll Drive 753 Herndon, VA 20170 754 USA 755 housley@vigilsec.com