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'SUITEBSMIME') (Obsoleted by RFC 6318) Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet-Draft R. Housley 3 Obsoletes: 5008 (if approved) Vigil Security 4 Intended Status: Informational J. Solinas 5 National Security Agency 6 Expires: October 27, 2011 April 25, 2011 8 Suite B in Secure/Multipurpose Internet Mail Extensions (S/MIME) 9 draft-housley-rfc5008bis-01 11 Abstract 13 This document specifies the conventions for using the United States 14 National Security Agency's Suite B algorithms in Secure/Multipurpose 15 Internet Mail Extensions (S/MIME) as specified in RFC 5751. This 16 document obsoletes RFC 5008. 18 Status of This Memo 20 This Internet-Draft is submitted to IETF 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 August 14, 2011. 35 Copyright Notice 37 Copyright (c) 2011 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 This document may contain material from IETF Documents or IETF 51 Contributions published or made publicly available before November 52 10, 2008. The person(s) controlling the copyright in some of this 53 material may not have granted the IETF Trust the right to allow 54 modifications of such material outside the IETF Standards Process. 55 Without obtaining an adequate license from the person(s) controlling 56 the copyright in such materials, this document may not be modified 57 outside the IETF Standards Process, and derivative works of it may 58 not be created outside the IETF Standards Process, except to format 59 it for publication as an RFC or to translate it into languages other 60 than English. 62 Table of Contents 64 1. Introduction .................................................. 3 65 1.1. Terminology ............................................. 4 66 1.2. ASN.1 ................................................... 4 67 1.3. Suite B Security Levels ................................. 4 68 2. SHA-256 and SHA-384 Message Digest Algorithms ................. 5 69 3. ECDSA Signature Algorithm .................................... 6 70 4. Key Management ................................................ 7 71 4.1. ECDH Key Agreement Algorithm ............................ 7 72 4.2. AES Key Wrap ............................................ 8 73 4.3. Key Derivation Functions ................................ 9 74 5. AES CBC Content Encryption ................................... 11 75 6. IANA Considerations .......................................... 11 76 7. Security Considerations ...................................... 12 77 8. References .................................................... 12 78 8.1. Normative References ................................... 12 79 8.2. Informative References ................................. 14 80 Authors' Addresses ............................................... 14 82 1. Introduction 84 The Fact Sheet on National Security Agency (NSA) Suite B Cryptography 85 [NSA] states: 87 A Cryptographic Interoperability Strategy (CIS) was developed to 88 find ways to increase assured rapid sharing of information both 89 within the U.S. and between the U.S. and her partners through the 90 use of a common suite of public standards, protocols, algorithms 91 and modes referred to as the "Secure Sharing Suite" or S.3. The 92 implementation of CIS will facilitate the development of a broader 93 range of secure cryptographic products which will be available to 94 a wide customer base. The use of selected public cryptographic 95 standards and protocols and Suite B is the core of CIS. 97 In 2005, NSA announced Suite B Cryptography which built upon the 98 National Policy on the use of the Advanced Encryption Standard 99 (AES) to Protect National Security Systems and National Security 100 Information. In addition to the AES algorithm, Suite B includes 101 cryptographic algorithms for key exchanges, digital signatures and 102 hashing. Suite B cryptography has been selected from cryptography 103 that has been approved by NIST for use by the U.S. Government and 104 specified in NIST standards or recommendations. 106 This document specifies the conventions for using the United States 107 National Security Agency's Suite B algorithms [NSA] in 108 Secure/Multipurpose Internet Mail Extensions (S/MIME) [MSG]. S/MIME 109 makes use of the Cryptographic Message Syntax (CMS) [CMS]. In 110 particular, the signed-data and the enveloped-data content types are 111 used. This document only addresses Suite B compliance for S/MIME. 112 Other applications of CMS are outside the scope of this document. 114 Since many of the Suite B algorithms enjoy uses in other environments 115 as well, the majority of the conventions needed for the Suite B 116 algorithms are already specified in other documents. This document 117 references the source of these conventions, with some relevant 118 details repeated to aid developers that choose to support Suite B. 120 This specification obsoletes RFC 5008 [SUITEBSMIME]. The primary 121 reason for the publication of this document is to allow greater 122 flexibility in the use of the Suite B Security Levels as discussed in 123 Section 1.3. It also removes some duplication between this document 124 and referenced RFCs. 126 1.1. Terminology 128 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 129 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 130 document are to be interpreted as described in RFC 2119 [STDWORDS]. 132 1.2. ASN.1 134 CMS values are generated using ASN.1 [X.208-88], the Basic Encoding 135 Rules (BER) [X.209-88], and the Distinguished Encoding Rules (DER) 136 [X.509-88]. 138 1.3. Suite B Security Levels 140 Suite B offers two suites of algorithms for key agreement, key 141 derivation, key wrap and content encryption and two possible 142 combinations of hash and signing algorithm. Suite B algorithms are 143 defined to support two minimum levels of cryptographic security: 128 144 and 192 bits. 146 For S/MIME signed messages, Suite B follows the direction set by RFC 147 5753 [CMSECC] and RFC 5754 [SHA2]. Suite B uses these combinations 148 of message digest (hash) and signature functions (Sig Sets): 150 Sig Set 1 Sig Set 2 151 ---------------- ---------------- 152 Message Digest: SHA-256 SHA-384 153 Signature: ECDSA with P-256 ECDSA with P-384 155 For S/MIME encrypted messages, Suite B follows the direction set by 156 RFC 5753 [CMSECC] and follows the conventions set by RFC 3565 157 [CMSAES]. 159 Suite B uses these key establishment (KE) algorithms (KE Sets): 161 KE Set 1 KE Set 2 162 ---------------- ---------------- 163 Key Agreement: ECDH with P-256 ECDH with P-384 164 Key Derivation: SHA-256 SHA-384 165 Key Wrap: AES-128 Key Wrap AES-256 Key Wrap 166 Content Encryption: AES-128 CBC AES-256 CBC 168 The two elliptic curves used in Suite B are specified in [DSS] and 169 each appear in the literature under two different names. For sake of 170 clarity, we list both names below: 172 Curve NIST Name SECG Name OID [DSS] 173 --------------------------------------------------------- 174 nistp256 P-256 secp256r1 1.2.840.10045.3.1.7 175 nistp384 P-384 secp384r1 1.3.132.0.34 177 If configured at a minimum level of security of 128 bits, a Suite B 178 compliant S/MIME system performing encryption MUST use either KE Set 179 1 or KE Set 2 with KE Set 1 the preferred suite. A digital 180 signature, if applied, MUST use either Sig Set 1 or Sig Set 2, 181 independent of the encryption choice. 183 A recipient in an S/MIME system configured at a minimum level of 184 security of 128 bits MUST be able to verify digital signatures from 185 Sig Set 1 and SHOULD be able to verify digital signatures from Sig 186 Set 2. 188 Note that for S/MIME systems configured at a minimum level of 189 security of 128 bits the algorithm set used for a signed-data content 190 type is independent of the algorithm set used for an enveloped-data 191 content type. 193 If configured at a minimum level of security of 192 bits, a Suite B 194 compliant S/MIME system performing encryption MUST use KE Set 2. A 195 digital signature, if applied, MUST use Sig Set 2. 197 A recipient in an S/MIME system configured at a minimum level of 198 security of 192 bits MUST be able to verify digital signatures from 199 Sig Set 2. 201 2. SHA-256 and SHA-384 Message Digest Algorithms 203 SHA-256 and SHA-384 are the Suite B message digest algorithms. RFC 204 5754 [SHA2] specifies the conventions for using SHA-256 and SHA-384 205 with the Cryptographic Message Syntax (CMS). Suite B compliant 206 S/MIME implementations MUST follow the conventions in RFC 5754. 207 Relevant details are repeated below. 209 Within the CMS signed-data content type, message digest algorithm 210 identifiers are located in the SignedData digestAlgorithms field and 211 the SignerInfo digestAlgorithm field. 213 The SHA-256 and SHA-384 message digest algorithms are defined in FIPS 214 Pub 180-3 [SHA2FIPS]. The algorithm identifiers for SHA-256 and 215 SHA-384 are defined in [SHA2] and are repeated here: 217 id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) 218 country(16) us(840) organization(1) gov(101) csor(3) 219 nistalgorithm(4) hashalgs(2) 1 } 221 id-sha384 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) 222 country(16) us(840) organization(1) gov(101) csor(3) 223 nistalgorithm(4) hashalgs(2) 2 } 225 For both SHA-256 and SHA-384, the AlgorithmIdentifier parameters 226 field is OPTIONAL, and if present, the parameters field MUST contain 227 a NULL. Implementations MUST accept SHA-256 and SHA-384 228 AlgorithmIdentifiers with absent parameters. Implementations MUST 229 accept SHA-256 and SHA-384 AlgorithmIdentifiers with NULL parameters. 230 As specified in RFC 5754 [SHA2], implementations MUST generate 231 SHA-256 and SHA-384 AlgorithmIdentifiers with absent parameters. 233 3. ECDSA Signature Algorithm 235 In Suite B, public key certificates used to verify S/MIME signatures 236 MUST be compliant with the Suite B Certificate Profile specified in 237 RFC 5759 [SUITEBCERT]. 239 The Elliptic Curve Digital Signature Algorithm (ECDSA) is the Suite B 240 digital signature algorithm. RFC 5753 [CMSECC] specifies the 241 conventions for using ECDSA with the Cryptographic Message Syntax 242 (CMS). Suite B compliant S/MIME implementations MUST follow the 243 conventions in RFC 5753. Relevant details are repeated below. 245 Within the CMS signed-data content type, signature algorithm 246 identifiers are located in the SignerInfo signatureAlgorithm field of 247 SignedData. In addition, signature algorithm identifiers are located 248 in the SignerInfo signatureAlgorithm field of countersignature 249 attributes. 251 RFC 5480 [PKI-ALG] defines the signature algorithm identifiers used 252 in CMS for ECDSA with SHA-256 and ECDSA with SHA-384. The 253 identifiers are repeated here: 255 ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2) 256 us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-sha2(3) 2 } 258 ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2) 259 us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-sha2(3) 3 } 261 When either the ecdsa-with-SHA256 or the ecdsa-with-SHA384 algorithm 262 identifier is used, the AlgorithmIdentifier parameters field MUST be 263 absent. 265 When signing, the ECDSA algorithm generates two values, commonly 266 called r and s. To transfer these two values as one signature, 267 they MUST be encoded using the ECDSA-Sig-Value type specified in RFC 268 5480 [PKI-ALG]: 270 ECDSA-Sig-Value ::= SEQUENCE { 271 r INTEGER, 272 s INTEGER } 274 4. Key Management 276 CMS accommodates the following general key management techniques: key 277 agreement, key transport, previously distributed symmetric key- 278 encryption keys, and passwords. In Suite B for S/MIME, ephemeral- 279 static key agreement MUST be used as described in Section 4.1. 281 When a key agreement algorithm is used, a key-encryption algorithm is 282 also needed. In Suite B for S/MIME, the Advanced Encryption Standard 283 (AES) Key Wrap, as specified in RFC 3394 [AESWRAP, SH], MUST be used 284 as the key-encryption algorithm. AES Key Wrap is discussed further 285 in Section 4.2. The key-encryption key used with the AES Key Wrap 286 algorithm is obtained from a key derivation function (KDF). In Suite 287 B for S/MIME, there are two KDFs, one based on SHA-256 and one based 288 on SHA-384. These KDFs are discussed further in Section 4.3. 290 4.1. ECDH Key Agreement Algorithm 292 Elliptic Curve Diffie-Hellman (ECDH) is the Suite B key agreement 293 algorithm. 295 S/MIME is used in store-and-forward communications, which means that 296 ephemeral-static ECDH is always employed. This means that the 297 message originator possesses an ephemeral ECDH key pair and that the 298 message recipient possesses a static ECDH key pair whose public key 299 is represented by an X.509 certificate. In Suite B, the certificate 300 used to obtain the recipient's public key MUST be compliant with the 301 Suite B Certificate Profile specified in RFC 5759 [SUITEBCERT]. 303 Section 3.1 of RFC 5753 [CMSECC] specifies the conventions for using 304 ECDH with the CMS. Suite B compliant S/MIME implementations MUST 305 follow these conventions. Relevant details are repeated below. 307 Within the CMS enveloped-data content type, key agreement algorithm 308 identifiers are located in the EnvelopedData RecipientInfos 309 KeyAgreeRecipientInfo keyEncryptionAlgorithm field. 311 keyEncryptionAlgorithm MUST be one of the two algorithm identifiers 312 listed below, and the algorithm identifier parameter field MUST be 313 present and identify the key wrap algorithm. The key wrap algorithm 314 denotes the symmetric encryption algorithm used to encrypt the 315 content-encryption key with the pairwise key-encryption key generated 316 using the ephemeral-static ECDH key agreement algorithm (see Section 317 4.3). 319 When implementing KE Set 1, the keyEncryptionAlgorithm MUST be 320 dhSinglePass-stdDH-sha256kdf-scheme and the keyEncryptionAlgorithm 321 parameter MUST be a KeyWrapAlgorithm containing id-aes128-wrap (see 322 Section 4.2). When implementing KE Set 2, the keyEncryptionAlgorithm 323 MUST be dhSinglePass-stdDH-sha384kdf-scheme and the 324 keyEncryptionAlgorithm parameter MUST be a KeyWrapAlgorithm 325 containing id-aes256-wrap. 327 The algorithm identifiers for dhSinglePass-stdDH-sha256kdf-scheme and 328 dhSinglePass-stdDH-sha384kdf-scheme, repeated from [CMSECC] Section 329 7.1.4, are: 331 dhSinglePass-stdDH-sha256kdf-scheme OBJECT IDENTIFIER ::= 332 { iso(1) identified-organization(3) certicom(132) 333 schemes(1) 11 1 } 335 dhSinglePass-stdDH-sha384kdf-scheme OBJECT IDENTIFIER ::= 336 { iso(1) identified-organization(3) certicom(132) 337 schemes(1) 11 2 } 339 Both of these algorithm identifiers use KeyWrapAlgorithm as the type 340 for their parameter: 342 KeyWrapAlgorithm ::= AlgorithmIdentifier 344 4.2. AES Key Wrap 346 The AES Key Wrap key-encryption algorithm, as specified in RFC 3394 347 [AESWRAP, SH], is used to encrypt the content-encryption key with a 348 pairwise key-encryption key that is generated using ephemeral-static 349 ECDH. Section 8 of RFC 5753 [CMSECC] specifies the conventions for 350 using AES Key Wrap with the pairwise key generated with epheneral- 351 static ECDH with the CMS. Suite B compliant S/MIME implementations 352 MUST follow these conventions. Relevant details are repeated below. 354 When implementing KE Set 1, the KeyWrapAlgorithm MUST be 355 id-aes128-wrap. When implementing KE Set 2, the KeyWrapAlgorithm 356 MUST be id-aes256-wrap. 358 Within the CMS enveloped-data content type, key wrap algorithm 359 identifiers are located in the KeyWrapAlgorithm parameters within the 360 EnvelopedData RecipientInfos KeyAgreeRecipientInfo 361 keyEncryptionAlgorithm field. 363 The algorithm identifiers for AES Key Wrap are specified in RFC 3394 364 [SH], and the ones needed for Suite B compliant S/MIME 365 implementations are repeated here: 367 id-aes128-wrap OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) 368 country(16) us(840) organization(1) gov(101) csor(3) 369 nistAlgorithm(4) aes(1) 5 } 371 id-aes256-wrap OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) 372 country(16) us(840) organization(1) gov(101) csor(3) 373 nistAlgorithm(4) aes(1) 45 } 375 4.3. Key Derivation Functions 377 KDFs based on SHA-256 and SHA-384 are used to derive a pairwise key- 378 encryption key from the shared secret produced by ephemeral-static 379 ECDH. Sections 7.1.8 and 7.2 of RFC 5753 [CMSECC] specify the 380 conventions for using the KDF with the shared secret generated with 381 ephemeral-static ECDH with the CMS. Suite B compliant S/MIME 382 implementations MUST follow these conventions. Relevant details are 383 repeated below. 385 When implementing KE Set 1, the KDF based on SHA-256 MUST be used. 386 When implementing KE Set 2, the KDF based on SHA-384 MUST be used. 388 As specified in Section 7.2 of RFC 5753 [CMSECC], using ECDH with the 389 CMS enveloped-data content type, the derivation of key-encryption 390 keys makes use of the ECC-CMS-SharedInfo type, which is repeated 391 here: 393 ECC-CMS-SharedInfo ::= SEQUENCE { 394 keyInfo AlgorithmIdentifier, 395 entityUInfo [0] EXPLICIT OCTET STRING OPTIONAL, 396 suppPubInfo [2] EXPLICIT OCTET STRING } 398 In Suite B for S/MIME, the fields of ECC-CMS-SharedInfo are used as 399 follows: 401 keyInfo contains the object identifier of the key-encryption 402 algorithm used to wrap the content-encryption key. In Suite B 403 for S/MIME, if the AES-128 Key Wrap is used, then the keyInfo 404 will contain id-aes128-wrap and the parameters will be absent. 405 In Suite B for S/MIME, if AES-256 Key Wrap is used, then the 406 keyInfo will contain id-aes256-wrap and the parameters will be 407 absent. 409 entityUInfo optionally contains a random value provided by the 410 message originator. If the ukm is present, then the 411 entityUInfo MUST be present, and it MUST contain the ukm value. 412 If the ukm is not present, then the entityUInfo MUST be absent. 414 suppPubInfo contains the length of the generated key-encryption 415 key, in bits, represented as a 32-bit unsigned number, as 416 described in RFC 2631 [CMSDH]. When a 128-bit AES key is used, 417 the length MUST be 0x00000080. When a 256-bit AES key is used, 418 the length MUST be 0x00000100. 420 ECC-CMS-SharedInfo is DER-encoded and used as input to the key 421 derivation function, as specified in Section 3.6.1 of [SEC1]. Note 422 that ECC-CMS-SharedInfo differs from the OtherInfo specified in 423 [CMSDH]. Here, a counter value is not included in the keyInfo field 424 because the KDF specified in [SEC1] ensures that sufficient keying 425 data is provided. 427 The KDF specified in [SEC1] provides an algorithm for generating an 428 essentially arbitrary amount of keying material from the shared 429 secret produced by ephemeral-static ECDH, which is called Z for the 430 remainder of this discussion. The KDF can be summarized as: 432 KM = Hash ( Z || Counter || ECC-CMS-SharedInfo ) 434 To generate a key-encryption key, one or more KM blocks are 435 generated, incrementing Counter appropriately, until enough material 436 has been generated. The KM blocks are concatenated left to right: 438 KEK = KM ( counter=1 ) || KM ( counter=2 ) ... 440 The elements of the KDF are used as follows: 442 Hash is the one-way hash function. If KE Set 1 is used, the 443 SHA-256 hash MUST be used. If KE Set 2 is used, the SHA-384 444 hash MUST be used. 446 Z is the shared secret value generated by ephemeral-static ECDH. 447 Leading zero bits MUST be preserved. In Suite B for S/MIME, if 448 KE Set 1 is used, Z MUST be exactly 256 bits. In Suite B for 449 S/MIME, if KE Set 2 is used, Z MUST be exactly 384 bits. 451 Counter is a 32-bit unsigned number, represented in network byte 452 order. Its initial value MUST be 0x00000001 for any key 453 derivation operation. In Suite B for S/MIME, with both KE Set 454 1 and KE Set 2, exactly one iteration is needed; the Counter is 455 not incremented. 457 ECC-CMS-SharedInfo is composed as described above. It MUST be DER 458 encoded. 460 To generate a key-encryption key, one KM block is generated, with a 461 Counter value of 0x00000001: 463 KEK = KM ( 1 ) = Hash ( Z || Counter=1 || ECC-CMS-SharedInfo ) 465 In Suite B for S/MIME, when KE Set 1 is used, the key-encryption key 466 MUST be the most significant 128 bits of the SHA-256 output value. 467 In Suite B for S/MIME, when KE Set 2 is used, the key-encryption key 468 MUST be the most significant 256 bits of the SHA-384 output value. 470 Note that the only source of secret entropy in this computation is Z. 471 The effective key space of the key-encryption key is limited by the 472 size of Z, in addition to any security level considerations imposed 473 by the elliptic curve that is used. However, if entityUInfo is 474 different for each message, a different key-encryption key will be 475 generated for each message. 477 5. AES CBC Content Encryption 479 AES [AES] in Cipher Block Chaining (CBC) mode [MODES] is the Suite B 480 for S/MIME content-encryption algorithm. RFC 3565 [CMSAES] specifies 481 the conventions for using AES with the CMS. Suite B compliant S/MIME 482 implementations MUST follow these conventions. Relevant details are 483 repeated below. 485 In Suite B for S/MIME, if KE Set 1 is used, AES-128 in CBC mode MUST 486 be used for content encryption. In Suite B for S/MIME, if KE Set 2 487 is used, AES-256 in CBC mode MUST be used. 489 Within the CMS enveloped-data content type, content encryption 490 algorithm identifiers are located in the EnvelopedData 491 EncryptedContentInfo contentEncryptionAlgorithm field. The content 492 encryption algorithm is used to encipher the content located in the 493 EnvelopedData EncryptedContentInfo encryptedContent field. 495 The AES CBC content-encryption algorithm is described in [AES] and 496 [MODES]. The algorithm identifier for AES-128 in CBC mode is: 498 id-aes128-CBC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) 499 country(16) us(840) organization(1) gov(101) csor(3) 500 nistAlgorithm(4) aes(1) 2 } 502 The algorithm identifier for AES-256 in CBC mode is: 504 id-aes256-CBC OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) 505 country(16) us(840) organization(1) gov(101) csor(3) 506 nistAlgorithm(4) aes(1) 42 } 508 The AlgorithmIdentifier parameters field MUST be present, and the 509 parameters field must contain AES-IV: 511 AES-IV ::= OCTET STRING (SIZE(16)) 513 The 16-octet initialization vector is generated at random by the 514 originator. See [RANDOM] for guidance on generation of random 515 values. 517 6. IANA Considerations 519 This document has no IANA considerations. 521 {{{ RFC Editor: Please delete this section prior to publication as an 522 RFC. }}} 524 7. Security Considerations 526 This document specifies the conventions for using the NSA's Suite B 527 algorithms in S/MIME. All of the algorithms and algorithm 528 identifiers have been specified in previous documents. 530 Two minimum levels of security may be achieved using this 531 specification. Users must consider their risk environment to 532 determine which level is appropriate for their own use. 534 See [RANDOM] for guidance on generation of random values. 536 The security considerations in RFC 5652 [CMS] discuss the CMS as a 537 method for digitally signing data and encrypting data. 539 The security considerations in RFC 3370 [CMSALG] discuss 540 cryptographic algorithm implementation concerns in the context of the 541 CMS. 543 The security considerations in RFC 5753 [CMSECC] discuss the use of 544 elliptic curve cryptography (ECC) in the CMS. 546 The security considerations in RFC 3565 [CMSAES] discuss the use of 547 AES in the CMS. 549 8. References 551 8.1. Normative References 553 [AES] National Institute of Standards and Technology, 554 "Advanced Encryption Standard (AES)", FIPS PUB 197, 555 November 2001. 557 [AESWRAP] National Institute of Standards and Technology, "AES 558 Key Wrap Specification", 17 November 2001. 559 [http://csrc.nist.gov/encryption/kms/key-wrap.pdf]. 561 [DSS] National Institute of Standards and Technology, 562 "Digital Signature Standard (DSS)", FIPS PUB 186-3, 563 June 2009. 565 [CMS] Housley, R., "Cryptographic Message Syntax (CMS)", 566 RFC 5652, September 2009. 568 [CMSAES] Schaad, J., "Use of the Advanced Encryption Standard 569 (AES) Encryption Algorithm in Cryptographic Message 570 Syntax (CMS)", RFC 3565, July 2003. 572 [CMSALG] Housley, R., "Cryptographic Message Syntax (CMS) 573 Algorithms", RFC 3370, August 2002. 575 [CMSDH] Rescorla, E., "Diffie-Hellman Key Agreement Method", 576 RFC 2631, June 1999. 578 [CMSECC] Turner, S., and D. Brown, "Use of Elliptic Curve 579 Cryptography (ECC) Algorithms in Cryptographic 580 Message Syntax (CMS)", RFC 5753, January 2010. 582 [MODES] National Institute of Standards and Technology, 583 "DES Modes of Operation", FIPS Pub 81, 584 2 December 1980. 586 [MSG] Ramsdell, B., and S. Turner, "Secure/Multipurpose 587 Internet Mail Extensions (S/MIME) Version 3.2 588 Message Specification", RFC 5751, January 2010. 590 [PKI-ALG] Turner, S., Brown, D., Yiu, K., Housley, R., and 591 T. Polk, "Elliptic Curve Cryptography Subject 592 Public Key Information", RFC 5480, March 2009. 594 [SEC1] Standards for Efficient Cryptography Group, 595 "Elliptic Curve Cryptography", 2000. 596 [http://www.secg.org/collateral/sec1.pdf]. 598 [SH] Schaad, J., and R. Housley, "Advanced Encryption 599 Standard (AES) Key Wrap Algorithm", RFC 3394, 600 September 2002. 602 [SHA2] Turner, S., "Using SHA2 Algorithms with Cryptographic 603 Message Syntax", RFC 5754, January 2010. 605 [SHA2FIPS] National Institute of Standards and Technology, "Secure 606 Hash Standard", FIPS 180-3, October 2008. 608 [STDWORDS] S. Bradner, "Key words for use in RFCs to Indicate 609 Requirement Levels", BCP 14, RFC 2119, March 1997. 611 [SUITEBCERT] 612 Solinas, J. and Zieglar, L., "Suite B Certificate and 613 Certificate Revocation List Profile", RFC 5759, January 614 2010. 616 [SUITEBSMIME] 617 Housley, R. and Solinas, J., "Suite B in 618 Secure/Multipurpose Internet Mail Extensions (S/MIME)", 619 RFC 5008, September 2007. 621 [X.208-88] CCITT. Recommendation X.208: Specification of Abstract 622 Syntax Notation One (ASN.1). 1988. 624 [X.209-88] CCITT. Recommendation X.209: Specification of Basic 625 Encoding Rules for Abstract Syntax Notation One (ASN.1). 626 1988. 628 [X.509-88] CCITT. Recommendation X.509: The Directory - 629 Authentication Framework. 1988. 631 8.2. Informative References 633 [RANDOM] Eastlake, D., 3rd, Schiller, J., and S. Crocker, 634 "Randomness Requirements for Security", BCP 106, 635 RFC 4086, June 2005. 637 [NSA] U.S. National Security Agency, "Fact Sheet NSA Suite B 638 Cryptography", January 2009. 639 [http://www.nsa.gov/ia/programs/suiteb_cryptography] 641 Authors' Addresses 643 Russell Housley 644 Vigil Security, LLC 645 918 Spring Knoll Drive 646 Herndon, VA 20170 647 USA 649 EMail: housley@vigilsec.com 651 Jerome A. Solinas 652 National Information Assurance Laboratory 653 National Security Agency 654 9800 Savage Road 655 Fort George G. Meade, MD 20755 656 USA 658 EMail: jasolin@orion.ncsc.mil