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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Storage Maintenance (storm) D. Black 3 Internet-Draft EMC 4 Updates: 3720, 3723, 3821, 3822, 4018, 4172, 4173, 4174, 5040, P. Koning 5 Intended status: Standards Track Dell 6 Expires: January 10, 2014 July 09, 2013 8 Securing Block Storage Protocols over IP: RFC 3723 Requirements Update 9 for IPsec v3 10 draft-ietf-storm-ipsec-ips-update-03 12 Abstract 14 RFC 3723 specifies IPsec requirements for block storage protocols 15 over IP (e.g., iSCSI) based on IPsec v2 (RFC 2401 and related RFCs); 16 those requirements have subsequently been applied to remote direct 17 data placement protocols, e.g., RDMAP. This document updates RFC 18 3723's IPsec requirements to IPsec v3 (RFC 4301 and related RFCs) and 19 makes some changes to required algorithms based on developments in 20 cryptography since RFC 3723 was published. 22 [RFC Editor: The "Updates:" list above has been truncated by xml2rfc. 23 The complete list is - Updates: 3720, 3723, 3821, 3822, 4018, 4172, 24 4173, 4174, 5040, 5041, 5042, 5043, 5044, 5045, 5046, 5047, 5048 (if 25 approved) ] 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at http://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on January 10, 2014. 44 Copyright Notice 46 Copyright (c) 2013 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 63 1.2. Summary of Changes to RFC 3723 . . . . . . . . . . . . . 3 64 1.3. Other Updated RFCs . . . . . . . . . . . . . . . . . . . 4 65 2. ESP Requirements . . . . . . . . . . . . . . . . . . . . . . 5 66 2.1. Data Origin Authentication and Data Integrity Transforms 6 67 2.2. Confidentiality Transform Requirements . . . . . . . . . 6 68 3. IKEv1 and IKEv2 Requirements . . . . . . . . . . . . . . . . 8 69 3.1. Authentication Requirements . . . . . . . . . . . . . . . 9 70 3.2. D-H Group and PRF Requirements . . . . . . . . . . . . . 10 71 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 72 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 73 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 74 6.1. Normative References . . . . . . . . . . . . . . . . . . 11 75 6.2. Informative References . . . . . . . . . . . . . . . . . 14 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 78 1. Introduction 80 RFC 3723 [RFC3723] specifies IPsec requirements for block storage 81 protocols over IP (e.g., iSCSI [RFC3720]) based on IPsec v2 (RFC 2401 82 [RFC2401] and related RFCs); those requirements have subsequently 83 been applied to remote direct data placement protocols, e.g., RDMAP 84 [RFC5040]. This document updates RFC 3723's IPsec requirements to 85 IPsec v3 ([RFC4301] and related RFCs) to reflect developments since 86 RFC 3723 was published. 88 For brevity, this document uses the term "block storage protocols" to 89 refer to all protocols to which RFC 3723's requirements apply, see 90 Section 1.3 for details. 92 In addition to the IPsec v2 requirements in RFC 3723, IPsec v3, as 93 specified in [RFC4301] and related RFCs (e.g., IKEv2 [RFC5996]), 94 SHOULD be implemented for block storage protocols. Retention of the 95 mandatory requirement for IPsec v2 provides interoperability with 96 existing implementations, and the strong recommendation for IPsec v3 97 encourages implementers to move forward to that newer version of 98 IPsec. 100 Cryptographic developments since the publication of RFC 3723 101 necessitate changes to the encryption transform requirements for 102 IPsec v2, as explained further in Section 2.2; these updated 103 requirements also apply to IPsec v3. 105 Block storage protocols can be expected to operate at high data rates 106 (multiple Gigabits/second). The cryptographic requirements in this 107 document are strongly influenced by that expectation; an important 108 example is that 3DES CBC is no longer recommended for block storage 109 protocols due to the frequent rekeying impacts of 3DES's 64-bit block 110 size at high data rates. 112 1.1. Requirements Language 114 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 115 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 116 document are to be interpreted as described in RFC 2119 [RFC2119]. 118 1.2. Summary of Changes to RFC 3723 120 This document makes the following changes to RFC 3723: 122 o Adds requirements that IPsec v3 SHOULD be implemented (ESPv3 and 123 IKEv2) in addition to IPsec v2, (see Section 1). The ESPv3 124 implementation requirement includes extended sequence numbers, see 125 Section 2. 127 o Clarifies key size requirements for AES CBC MAC with XCBC 128 extensions (MUST implement 128 bit keys, see Section 2.1). 130 o Adds IPsec v3 requirements for AES GMAC and GCM (SHOULD implement 131 when IKEv2 is supported, see Section 2.1 and Section 2.2). 133 o Removes implementation requirements for 3DES CBC and AES CTR 134 (changes requirements for both to "MAY implement"). Adds a "MUST 135 implement" requirement for AES CBC (see Section 2.2). 137 o Adds specific IKEv2 implementation requirements (see Section 3). 139 o Removes the requirement that IKEv1 use UDP port 500, and changes 140 the Diffie-Hellman group size recommendation to a minimum of 2048 141 bits (see Section 3). 143 1.3. Other Updated RFCs 145 RFC 3723's IPsec requirements have been applied to a number of 146 protocols. For that reason, in addition to updating RFC 3723's IPsec 147 requirements, this document also updates the IPsec requirements for 148 each protocol that uses RFC 3723, i.e., the following RFCs are 149 updated - in each case, the update is solely to the IPsec 150 requirements: 152 o [RFC3720] "Internet Small Computer Systems Interface (iSCSI)" 154 o [RFC3821] "Fibre Channel Over TCP/IP (FCIP)" 156 o [RFC3822] "Finding Fibre Channel over TCP/IP (FCIP) Entities Using 157 Service Location Protocol version 2 (SLPv2)" 159 o [RFC4018] "Finding Internet Small Computer Systems Interface 160 (iSCSI) Targets and Name Servers by Using Service Location 161 Protocol version 2 (SLPv2)" 163 o [RFC4172] "iFCP - A Protocol for Internet Fibre Channel Storage 164 Networking" 166 o [RFC4173] "Bootstrapping Clients using the Internet Small Computer 167 System Interface (iSCSI) Protocol" 169 o [RFC4174] "The IPv4 Dynamic Host Configuration Protocol (DHCP) 170 Option for the Internet Storage Name Service" 172 o [RFC5040] "A Remote Direct Memory Access Protocol Specification" 174 o [RFC5041] "Direct Data Placement over Reliable Transports" 176 o [RFC5042] "Direct Data Placement Protocol (DDP) / Remote Direct 177 Memory Access Protocol (RDMAP) Security" 179 o [RFC5043] "Stream Control Transmission Protocol (SCTP) Direct Data 180 Placement (DDP) Adaptation" 182 o [RFC5044] "Marker PDU Aligned Framing for TCP Specification" 184 o [RFC5045] "Applicability of Remote Direct Memory Access Protocol 185 (RDMA) and Direct Data Placement (DDP)" 187 o [RFC5046] "Internet Small Computer System Interface (iSCSI) 188 Extensions for Remote Direct Memory Access (RDMA)" 190 o [RFC5047] "DA: Datamover Architecture for the Internet Small 191 Computer System Interface (iSCSI)" 193 o [RFC5048] "Internet Small Computer System Interface (iSCSI) 194 Corrections and Clarifications" 196 [RFC3721] and [RFC5387] are not updated by this document, as their 197 usage of RFC 3723 does not encompass its IPsec requirements. 199 In addition, this document's updated IPsec requirements apply to the 200 new specifications for iSCSI ([I-D.ietf-storm-iscsi-cons]) and iSER ( 201 [I-D.ietf-storm-iser]). 203 This document uses the term "block storage protocols" to refer to the 204 protocols (listed above) to which RFC 3723's requirements (as updated 205 by the requirements in this document) apply. 207 2. ESP Requirements 209 RFC 3723 requires that implementations MUST support IPsec ESPv2 210 [RFC2406] in tunnel mode as part of IPsec v2 to provide security for 211 both control packets and data packets, and that when ESPv2 is 212 utilized, per-packet data origin authentication, integrity and replay 213 protection MUST be provided. 215 This document modifies RFC 3723 to require that implementations 216 SHOULD also support IPsec ESPv3 [RFC4303] in tunnel mode as part of 217 IPsec v3 to provide security for both control packets and data 218 packets; per-packet data origin authentication, integrity and replay 219 protection MUST be provided when ESPv3 is utilized. 221 At the high speeds at which block storage protocols are expected to 222 operate, a single IPsec SA could rapidly cycle through the ESP 32-bit 223 sequence number space. In view of this, implementations that are 224 capable of operating at speeds of 1 gigabit/second or higher and that 225 implement both IKEv2 [RFC5996] and ESPv3 [RFC4303] MUST also 226 implement extended (64-bit) sequence numbers for ESPv3 and SHOULD use 227 ESPv3 extended sequence numbers for all block storage protocol 228 traffic. 230 2.1. Data Origin Authentication and Data Integrity Transforms 232 RFC 3723 requires that: 234 o HMAC-SHA1 MUST be implemented in the form of HMAC-SHA-1-96 235 [RFC2404]. 237 o AES CBC MAC with XCBC extensions SHOULD be implemented [RFC3566]. 239 This document clarifies RFC 3723's key size requirements for 240 implementations of AES CBC MAC with XCBC extensions; 128-bit keys 241 MUST be supported, and other key sizes MAY also be supported. 243 This document also adds a requirement for IPsec v3: 245 o Implementations that support IKEv2 [RFC5996] SHOULD also implement 246 AES GMAC [RFC4543]. AES GMAC implementations MUST support 128-bit 247 keys, and MAY support other key sizes. 249 The rationale for the added requirement is that GMAC is more amenable 250 to hardware implementations that may be preferable for the high data 251 rates at which block storage protocols can be expected to operate. 253 2.2. Confidentiality Transform Requirements 255 RFC 3723 requires that: 257 o 3DES in CBC mode (3DES CBC) [RFC2451], [triple-des-spec] MUST be 258 supported. 260 o AES in Counter mode (AES CTR) [RFC3686], SHOULD be supported. 262 o NULL encryption [RFC2410] MUST be supported. 264 The 3DES CBC and AES CTR requirements are replaced by requirements 265 that both MAY be implemented. The NULL encryption requirement is not 266 changed by this document. The 3DES CBC requirement matched the basic 267 encryption interoperability requirement for IPsec v2. At the time of 268 RFC 3723's publication, AES Counter mode was the encryption transform 269 that was most amenable to hardware implementation, as hardware 270 implementation may be preferable for the high data rates at which 271 block storage protocols can be expected to operate. This document 272 changes both of these requirements based on cryptographic 273 developments since the publication of RFC 3723. 275 The requirement for 3DES CBC has become problematic due to 3DES's 276 64-bit block size, i.e., the core cipher encrypts or decrypts 64 bits 277 at a time. Security weaknesses in encryption start to appear as the 278 amount of data encrypted under a single key approaches the birthday 279 bound of 32GiB for a cipher with a 64-bit block size, see Appendix A 280 and [triple-des-birthday]. It is prudent to rekey well before that 281 bound is reached, and 32GiB or some significant fraction thereof is 282 less than the amount of data that a block storage protocol may 283 transfer in a single session. This may require frequent rekeying, 284 e.g., to obtain an order of magnitude (10x) safety margin by rekeying 285 after 3GiB on a multi-gigabit/sec link. In contrast, AES has a 128 286 bit block size, which results in a much larger birthday bound (2^68 287 bytes), see Appendix A. AES CBC is the primary mandatory-to-implement 288 encryption transform for interoperability, and hence is the 289 appropriate mandatory-to-implement transform replacement for 3DES 290 CBC. 292 AES Counter mode is no longer the encryption transform that is most 293 amenable to hardware implementation. That characterization now 294 applies to AES Galois Counter Mode (GCM) [RFC4106], which provides 295 both encryption and integrity protection in a single cryptographic 296 mechanism (in contrast, neither HMAC-SHA1 nor AES CBC MAC with XCBC 297 extensions is well suited for hardware implementation, as both 298 transforms do not pipeline well). AES GCM is also capable of 299 providing confidentiality protection for the IKEv2 key exchange 300 protocol, but not the IKEv1 protocol [RFC5282], and therefore the new 301 AES GCM "SHOULD" requirement is based on presence of support for 302 IKEv2. 304 For the reasons described in the preceding paragraphs, the 305 confidentiality transform requirements in RFC 3723 are replaced by 306 the following: 308 o 3DES in CBC mode MAY be implemented (replaces RFC 3723's "MUST 309 implement" requirement) . 311 o AES in Counter mode MAY be implemented (replaces RFC 3723's 312 "SHOULD implement" requirement). 314 o AES in CBC mode MUST be implemented. AES CBC implementations MUST 315 support 128-bit keys and MAY support other key sizes. 317 o Implementations that support IKEv2 SHOULD also implement AES GCM. 318 AES GCM implementations MUST support 128-bit keys, and MAY support 319 other key sizes. 321 o NULL encryption [RFC2410] MUST be supported. 323 The requirement for support of NULL encryption enables use of SAs 324 that provide data origin authentication and data integrity, but not 325 confidentiality. 327 Other transforms MAY be implemented in addition to those listed 328 above. 330 3. IKEv1 and IKEv2 Requirements 332 Note: to avoid ambiguity, the original IKE protocol [RFC2409] is 333 referred to as "IKEv1" in this document. 335 This document adds requirements for IKEv2 usage with block Storage 336 protocols and makes the following two changes to the IKEv1 337 requirements in RFC 3723 (the new D-H group requirement also applies 338 to IKEv2): 340 o When D-H groups are used, a D-H group of at least 2048 bits SHOULD 341 be offered as a part of all proposals to create IPsec Security 342 Associations. Use of 1024 bit D-H groups with 3DES CBC and HMAC- 343 SHA1 is no longer recommended, and 345 o The requirement to use UDP port 500 is removed in order to allow 346 NAT traversal [RFC3947]. 348 There are no other changes to RFC 3723's IKEv1 requirements, but many 349 of them are restated in this document in order to provide context for 350 the new IKEv2 requirements. 352 RFC 3723 requires that IKEv1 [RFC2409] be supported for peer 353 authentication, negotiation of security associations, and key 354 management, using the IPsec DOI [RFC2407], and further requires that 355 manual keying not be used since it does not provide the rekeying 356 support necessary for operation at high data rates. This document 357 adds a requirement that IKEv2 [RFC5996] SHOULD be supported for peer 358 authentication, negotiation of security associations, and key 359 management. The manual keying prohibition in RFC 3723 is extended to 360 IKEv2; manual keying MUST NOT be used with any version of IPsec for 361 protocols to which the requirements in this document apply. 363 RFC 3723's requirements for IKEv1 mode implementation and usage are 364 unchanged; this document does not extend those requirements to IKEv2 365 because IKEv2 does not have modes. 367 When IPsec is used, the receipt of an IKEv1 Phase 2 delete message or 368 an IKEv2 INFORMATIONAL exchange that deletes the SA SHOULD NOT be 369 interpreted as a reason for tearing down the block storage protocol 370 connection (e.g., TCP-based). If additional traffic is sent, a new 371 SA will be created to protect that traffic. 373 The method used to determine whether a block storage protocol 374 connection should be established using IPsec is regarded as an issue 375 of IPsec policy administration, and thus is not defined in this 376 document. The method used by an implementation that supports both 377 IPsec v2 and v3 to determine which versions of IPsec are supported by 378 the a block storage protocol peer is also regarded as an issue of 379 IPsec policy administration, and thus is also not defined in this 380 document. If both IPsec v2 and v3 are supported by both endpoints of 381 a block storage protocol connection, use of IPsec v3 is recommended. 383 3.1. Authentication Requirements 385 The authentication requirements for IKEv1 are unchanged by this 386 document, but are restated here for context along with the 387 authentication requirements for IKEv2: 389 a. Peer authentication using a pre-shared cryptographic key MUST be 390 supported. Certificate-based peer authentication using digital 391 signatures MAY be supported. For IKEv1 ([RFC2409]), peer 392 authentication using the public key encryption methods specified 393 in sections 5.2 and 5.3 of [RFC2409] SHOULD NOT be used. 395 b. When digital signatures are used for authentication, all IKEv1 396 and IKEv2 negotiators SHOULD use Certificate Request Payload(s) 397 to specify the certificate authority, and SHOULD check the 398 pertinent Certificate Revocation List (CRL) before accepting a 399 PKI certificate for use in authentication. 401 c. IKEv1 implementations MUST support Main Mode and SHOULD support 402 Aggressive Mode. Main Mode with pre-shared key authentication 403 method SHOULD NOT be used when either the initiator or the target 404 uses dynamically assigned IP addresses. While in many cases pre- 405 shared keys offer good security, situations in which dynamically 406 assigned addresses are used force the use of a group pre-shared 407 key, which creates vulnerability to a man-in-the-middle attack. 408 These requirements do not apply to IKEv2 because it has no modes. 410 d. In the IKEv1 Phase 2 Quick Mode, exchanges for creating the Phase 411 2 SA, the Identification Payload MUST be present. This 412 requirement does not apply to IKEv2 because it has no modes. 414 e. The following identification type requirements apply to IKEv1. 415 ID_IPV4_ADDR, ID_IPV6_ADDR (if the protocol stack supports IPv6) 416 and ID_FQDN Identification Types MUST be supported; ID_USER_FQDN 417 SHOULD be supported. The IP Subnet, IP Address Range, 418 ID_DER_ASN1_DN, and ID_DER_ASN1_GN Identification Types SHOULD 419 NOT be used. The ID_KEY_ID Identification Type MUST NOT be used. 421 f. When IKEv2 is supported, the following identification 422 requirements apply. ID_IPV4_ADDR, ID_IPV6_ADDR (if the protocol 423 stack supports IPv6) and ID_FQDN Identification Types MUST be 424 supported; ID_RFC822_ADDR SHOULD be supported. The 425 ID_DER_ASN1_DN, and ID_DER_ASN1_GN Identification Types SHOULD 426 NOT be used. The ID_KEY_ID Identification Type MUST NOT be used. 428 The reasons for the identification requirements in items e and f 429 above are: 431 o IP Subnet and IP Address Range are too broad to usefully identify 432 an iSCSI endpoint. 434 o The _DN and _GN types are X.500 identities; it is usually better 435 to use an identity from subjectAltName in a PKI certificate. 437 o ID_KEY_ID is an opaque identifier that is not interoperable among 438 different IPsec implementations as specified. Heterogeneity in 439 some block storage protocol implementations can be expected (e.g., 440 iSCSI initiator vs. iSCSI target implementations), and hence 441 heterogeneity among IPsec implementations is important. 443 3.2. D-H Group and PRF Requirements 445 This document does not change the support requirements for Diffe- 446 Hellman (D-H) groups and Pseudo-Random Functions (PRFs). See 447 [RFC4109] for IKEv1 requirements and [RFC4307] for IKEv2 448 requirements. Implementors are advised to check for subsequent RFCs 449 that update either of these RFCs, as such updates may change these 450 requirements. 452 When DH groups are used, a DH group of at least 2048 bits SHOULD be 453 offered as a part of all proposals to create IPsec Security 454 Associations for both IKEv1 and IKEv2. 456 RFC 3723 requires that the IKEv1 Quick Mode key exchange that 457 provides perfect forward secrecy MUST be implemented. This document 458 extends that requirement to IKEv2; the CREATE_CHILD_SA key exchange 459 that provides perfect forward secrecy MUST be implemented for use of 460 IPsec with block storage protocols. 462 4. IANA Considerations 464 This document includes no request to IANA. 466 5. Security Considerations 468 This entire document is about security. 470 6. References 472 6.1. Normative References 474 [I-D.ietf-storm-iscsi-cons] 475 Chadalapaka, M., Satran, J., Meth, K., and D. Black, 476 "iSCSI Protocol (Consolidated)", draft-ietf-storm-iscsi- 477 cons-09 (work in progress), June 2013. 479 [I-D.ietf-storm-iser] 480 Ko, M. and A. Nezhinsky, "iSCSI Extensions for RDMA 481 Specification", draft-ietf-storm-iser-14 (work in 482 progress), June 2013. 484 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 485 Requirement Levels", BCP 14, RFC 2119, March 1997. 487 [RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the 488 Internet Protocol", RFC 2401, November 1998. 490 [RFC2404] Madson, C. and R. Glenn, "The Use of HMAC-SHA-1-96 within 491 ESP and AH", RFC 2404, November 1998. 493 [RFC2406] Kent, S. and R. Atkinson, "IP Encapsulating Security 494 Payload (ESP)", RFC 2406, November 1998. 496 [RFC2407] Piper, D., "The Internet IP Security Domain of 497 Interpretation for ISAKMP", RFC 2407, November 1998. 499 [RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange 500 (IKE)", RFC 2409, November 1998. 502 [RFC2410] Glenn, R. and S. Kent, "The NULL Encryption Algorithm and 503 Its Use With IPsec", RFC 2410, November 1998. 505 [RFC2451] Pereira, R. and R. Adams, "The ESP CBC-Mode Cipher 506 Algorithms", RFC 2451, November 1998. 508 [RFC3566] Frankel, S. and H. Herbert, "The AES-XCBC-MAC-96 Algorithm 509 and Its Use With IPsec", RFC 3566, September 2003. 511 [RFC3686] Housley, R., "Using Advanced Encryption Standard (AES) 512 Counter Mode With IPsec Encapsulating Security Payload 513 (ESP)", RFC 3686, January 2004. 515 [RFC3720] Satran, J., Meth, K., Sapuntzakis, C., Chadalapaka, M., 516 and E. Zeidner, "Internet Small Computer Systems Interface 517 (iSCSI)", RFC 3720, April 2004. 519 [RFC3723] Aboba, B., Tseng, J., Walker, J., Rangan, V., and F. 520 Travostino, "Securing Block Storage Protocols over IP", 521 RFC 3723, April 2004. 523 [RFC3821] Rajagopal, M., Rodriguez, E., and R. Weber, "Fibre Channel 524 Over TCP/IP (FCIP)", RFC 3821, July 2004. 526 [RFC3822] Peterson, D., "Finding Fibre Channel over TCP/IP (FCIP) 527 Entities Using Service Location Protocol version 2 528 (SLPv2)", RFC 3822, July 2004. 530 [RFC3947] Kivinen, T., Swander, B., Huttunen, A., and V. Volpe, 531 "Negotiation of NAT-Traversal in the IKE", RFC 3947, 532 January 2005. 534 [RFC4018] Bakke, M., Hufferd, J., Voruganti, K., Krueger, M., and T. 535 Sperry, "Finding Internet Small Computer Systems Interface 536 (iSCSI) Targets and Name Servers by Using Service Location 537 Protocol version 2 (SLPv2)", RFC 4018, April 2005. 539 [RFC4106] Viega, J. and D. McGrew, "The Use of Galois/Counter Mode 540 (GCM) in IPsec Encapsulating Security Payload (ESP)", RFC 541 4106, June 2005. 543 [RFC4109] Hoffman, P., "Algorithms for Internet Key Exchange version 544 1 (IKEv1)", RFC 4109, May 2005. 546 [RFC4172] Monia, C., Mullendore, R., Travostino, F., Jeong, W., and 547 M. Edwards, "iFCP - A Protocol for Internet Fibre Channel 548 Storage Networking", RFC 4172, September 2005. 550 [RFC4173] Sarkar, P., Missimer, D., and C. Sapuntzakis, 551 "Bootstrapping Clients using the Internet Small Computer 552 System Interface (iSCSI) Protocol", RFC 4173, September 553 2005. 555 [RFC4174] Monia, C., Tseng, J., and K. Gibbons, "The IPv4 Dynamic 556 Host Configuration Protocol (DHCP) Option for the Internet 557 Storage Name Service", RFC 4174, September 2005. 559 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 560 Internet Protocol", RFC 4301, December 2005. 562 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 563 4303, December 2005. 565 [RFC4307] Schiller, J., "Cryptographic Algorithms for Use in the 566 Internet Key Exchange Version 2 (IKEv2)", RFC 4307, 567 December 2005. 569 [RFC4543] McGrew, D. and J. Viega, "The Use of Galois Message 570 Authentication Code (GMAC) in IPsec ESP and AH", RFC 4543, 571 May 2006. 573 [RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D. 574 Garcia, "A Remote Direct Memory Access Protocol 575 Specification", RFC 5040, October 2007. 577 [RFC5041] Shah, H., Pinkerton, J., Recio, R., and P. Culley, "Direct 578 Data Placement over Reliable Transports", RFC 5041, 579 October 2007. 581 [RFC5042] Pinkerton, J. and E. Deleganes, "Direct Data Placement 582 Protocol (DDP) / Remote Direct Memory Access Protocol 583 (RDMAP) Security", RFC 5042, October 2007. 585 [RFC5043] Bestler, C. and R. Stewart, "Stream Control Transmission 586 Protocol (SCTP) Direct Data Placement (DDP) Adaptation", 587 RFC 5043, October 2007. 589 [RFC5044] Culley, P., Elzur, U., Recio, R., Bailey, S., and J. 590 Carrier, "Marker PDU Aligned Framing for TCP 591 Specification", RFC 5044, October 2007. 593 [RFC5046] Ko, M., Chadalapaka, M., Hufferd, J., Elzur, U., Shah, H., 594 and P. Thaler, "Internet Small Computer System Interface 595 (iSCSI) Extensions for Remote Direct Memory Access 596 (RDMA)", RFC 5046, October 2007. 598 [RFC5048] Chadalapaka, M., "Internet Small Computer System Interface 599 (iSCSI) Corrections and Clarifications", RFC 5048, October 600 2007. 602 [RFC5282] Black, D. and D. McGrew, "Using Authenticated Encryption 603 Algorithms with the Encrypted Payload of the Internet Key 604 Exchange version 2 (IKEv2) Protocol", RFC 5282, August 605 2008. 607 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 608 "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 609 5996, September 2010. 611 [triple-des-birthday] 612 McGrew, D., "Impossible plaintext cryptanalysis and 613 probable-plaintext collision attacks of 64-bit block 614 cipher modes (Cryptology ePrint Archive: Report 2012/ 615 623)", November 2012, . 617 [triple-des-spec] 618 American Bankers Association, ABA., "American National 619 Standard for Financial Services X9.52-1998 - Triple Data 620 Encryption Algorithm Modes of Operation", July 1998. 622 6.2. Informative References 624 [RFC3721] Bakke, M., Hafner, J., Hufferd, J., Voruganti, K., and M. 625 Krueger, "Internet Small Computer Systems Interface 626 (iSCSI) Naming and Discovery", RFC 3721, April 2004. 628 [RFC5045] Bestler, C. and L. Coene, "Applicability of Remote Direct 629 Memory Access Protocol (RDMA) and Direct Data Placement 630 (DDP)", RFC 5045, October 2007. 632 [RFC5047] Chadalapaka, M., Hufferd, J., Satran, J., and H. Shah, 633 "DA: Datamover Architecture for the Internet Small 634 Computer System Interface (iSCSI)", RFC 5047, October 635 2007. 637 [RFC5387] Touch, J., Black, D., and Y. Wang, "Problem and 638 Applicability Statement for Better-Than-Nothing Security 639 (BTNS)", RFC 5387, November 2008. 641 Appendix A. Block Cipher Birthday Bounds 643 This Appendix provides the birthday bounds for the 3DES and AES 644 ciphers based on [triple-des-birthday], which states: "Theory advises 645 against using a w-bit block cipher to encrypt more than 2^(w/2) 646 blocks with a single key; this is known as the birthday bound." 648 For a cipher with a 64-bit block size (e.g., 3DES), w=64, so the 649 birthday bound is 2^32 blocks. As each block contains 8 (2^3) bytes, 650 the birthday bound is 2^35 bytes = 2^5 gibibytes, i.e., 32 GiB, where 651 1 gibibyte (GiB) = 2^30 bytes. Note that a gigabyte (decimal 652 quantity) is not the same as a gibibyte (binary quantity), 1 gigabyte 653 (GB) = 10^6 bytes. 655 For a cipher with a 128-bit block size (e.g., AES), w=128, so the 656 birthday bound is 2^64 blocks. As each block contains 16 (2^4) 657 bytes, the birthday bound is 2^68 bytes = 2^8 exbibytes, i.e., 256 658 EiB, where 1 exbibyte (EiB) = 2^60 bytes. Note that an exabyte 659 (decimal quantity) is not the same as an exbibyte (binary quantity), 660 1 exabyte (EB) = 10^9 bytes. 662 Appendix B. Contributors 664 David McGrew's observations about the birthday bound implications of 665 3DES's 64-bit block size on the ipsec@ietf.org mailing list lead to 666 changing from 3DES CBC to AES CBC as the mandatory to implement 667 encryption algorithm and including the birthday bound material in 668 Appendix A. 670 The original authors of RFC 3723 were: Bernard Aboba, Joshua Tseng, 671 Jesse Walker, Venkat Rangan and Franco Travostino. Comments from 672 Yaron Sheffer and Tom Talpey have improved this document and are 673 gratefully acknowledged. 675 Appendix C. Change Log 677 This section should be removed before this document is published as 678 an RFC 680 Changes from -00 to -01: 682 o Make it clearer that RFC 3723's encryption implementation 683 requirements are being changed. 685 o State that D-H group and PRF implementation requirements are 686 unchanged and provide references to RFCs where they can be found 687 (new section 3.2). 689 o Add requirements for perfect forward secrecy implementation (also 690 in 3.2). 692 o Use the correct GMAC reference. 694 o Many other editorial changes. 696 Changes from -01 to -02. 698 o Remove "IP Storage" terminology, use "Block Storage" in title and 699 body, based on RFC 3723. 701 o Add appendix on birthday bound calculations. 703 o Clean up and tighten requirements text, with a focus on making key 704 size requirements clearer. 706 o Add summary of changes from RFC 3723. 708 o Many other editorial changes. 710 Authors' Addresses 712 David Black 713 EMC 714 176 South Street 715 Hopkinton, MA 01748 716 US 718 Phone: +1 508 293-7953 719 Email: david.black@emc.com 721 Paul Koning 722 Dell 723 300 Innovative Way 724 Nashua, NH 03062 725 US 727 Phone: +1 603 249-7703 728 Email: paul_koning@Dell.com