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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 OSPF Working Group M. Bhatia 3 Internet-Draft Ionos Networks 4 Intended status: Standards Track S. Hartman 5 Expires: April 9, 2015 Painless Security 6 D. Zhang 7 Huawei Technologies co., LTD. 8 A. Lindem 9 Cisco 10 October 6, 2014 12 Security Extension for OSPFv2 when using Manual Key Management 13 draft-ietf-ospf-security-extension-manual-keying-09 15 Abstract 17 The current OSPFv2 cryptographic authentication mechanism as defined 18 in RFC 2328 and RFC 5709 is vulnerable to both inter-session and 19 intra-session replay attacks when using manual keying. Additionally, 20 the existing cryptographic authentication mechanism does not cover 21 the IP header. This omission can be exploited to carry out various 22 types of attacks. 24 This draft proposes changes to the authentication sequence number 25 mechanism that will protect OSPFv2 from both inter-session and intra- 26 session replay attacks when using manual keys for securing OSPFv2 27 protocol packets. Additionally, we also describe some changes in the 28 cryptographic hash computation that will eliminate attacks resulting 29 from OSPFv2 not protecting the IP header. 31 Status of this Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on April 9, 2015. 48 Copyright Notice 49 Copyright (c) 2014 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 1.1. Requirements Section . . . . . . . . . . . . . . . . . . . 3 66 1.2. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 4 67 2. Replay Protection using Extended Sequence Numbers . . . . . . 4 68 3. OSPF Packet Extensions . . . . . . . . . . . . . . . . . . . . 5 69 4. OSPF Packet Key Selection . . . . . . . . . . . . . . . . . . 6 70 4.1. Key Selection for Unicast OSPF Packet Transmission . . . . 7 71 4.2. Key Selection for Multicast OSPF Packet Transmission . . . 8 72 4.3. Key Selection for OSPF Packet Reception . . . . . . . . . 8 73 5. Securing the IP header . . . . . . . . . . . . . . . . . . . . 9 74 6. Mitigating Cross-Protocol Attacks . . . . . . . . . . . . . . 9 75 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 76 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 77 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 78 9.1. Normative References . . . . . . . . . . . . . . . . . . . 11 79 9.2. Informative References . . . . . . . . . . . . . . . . . . 12 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 82 1. Introduction 84 The OSPFv2 cryptographic authentication mechanism as described in 85 [RFC2328] uses per-packet sequence numbers to provide protection 86 against replay attacks. The sequence numbers increase monotonically 87 so that attempts to replay stale packets can be thwarted. The 88 sequence number values are maintained as a part of neighbor adjacency 89 state. Therefore, if an adjacency is taken down, the associated 90 sequence numbers get reinitialized and neighbor adjacency formation 91 starts over again. Additionally, the cryptographic authentication 92 mechanism does not specify how to deal with the rollover of a 93 sequence number when its value wraps. These omissions can be 94 exploited by attackers to implement various replay attacks 95 ([RFC6039]). In order to address these issues, we propose extensions 96 to the authentication sequence number mechanism. 98 The cryptographic authentication as described in [RFC2328] and later 99 updated in [RFC5709] does not include the IP header. This omission 100 can be exploited to launch several attacks as the source address in 101 the IP header is not protected. The OSPF specification, for 102 broadcast and NBMA (Non-Broadcast Multi-Access Networks), requires 103 implementations to use the source address in the IP header to 104 determine the neighbor from which the packet was received. Changing 105 the IP source address of a packet to a conflicting IP address can be 106 exploited to produce a number of denial of service attacks [RFC6039]. 107 If the packet is interpreted as coming from a different neighbor, the 108 received sequence number state for that neighbor may be incorrectly 109 updated. This attack may disrupt communication with a legitimate 110 neighbor. Hello packets may be reflected to cause a neighbor to 111 appear to have one-way communication. Additionally, Database 112 Description packets may be reflected in cases where the per-packet 113 sequence numbers are sufficiently divergent in order to disrupt an 114 adjacency [RFC6863]. This is referred to as the IP layer issue in 115 [RFC6862]. 117 [RFC2328] states that implementations MUST offer keyed MD5 118 authentication. It is likely that this will be deprecated in favor 119 of the stronger algorithms described in [RFC5709] and required in 120 [RFC6094]. 122 This draft proposes a few simple changes to the cryptographic 123 authentication mechanism, as currently described in [RFC5709], to 124 prevent such IP layer attacks. 126 1.1. Requirements Section 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 RFC2119 [RFC2119]. 132 When used in lowercase, these words convey their typical use in 133 common language, and are not to be interpreted as described in 134 RFC2119 [RFC2119]. 136 1.2. Acknowledgments 138 Thanks to Ran Atkinson for help in the analysis of RFC 6506 errata 139 leading to clarifications in this document. Thanks to Gabi Nakibly 140 for pointing out the possible attack on p2p links. 142 2. Replay Protection using Extended Sequence Numbers 144 In order to provide replay protection against both inter-session and 145 intra-session replay attacks, the OSPFv2 sequence number is expanded 146 to 64-bits with the least significant 32-bit value containing a 147 strictly increasing sequence number and the most significant 32-bit 148 value containing the boot count. OSPFv2 implementations are required 149 to retain the boot count in non-volatile storage for the deployment 150 life the OSPF router. The requirement to preserve the boot count is 151 also placed on SNMP agents by the SNMPv3 security architecture (refer 152 to snmpEngineBoots in [RFC4222]). 154 Since there is no room in the OSPFv2 packet for a 64-bit sequence 155 number, it will occupy the 8 octets following the OSPFv2 packet and 156 MUST be included when calculating the OSPFv2 packet digest. These 157 additional 8 bytes are not included in the OSPFv2 packet header 158 length but are included in the OSPFv2 header Authentication Data 159 length and the IPv4 packet header length. 161 The lower order 32-bit sequence number MUST be incremented for every 162 OSPF packet sent by the OSPF router. Upon reception, the sequence 163 number MUST be greater than the sequence number in the last OSPF 164 packet of that type accepted from the sending OSPF neighbor. 165 Otherwise, the OSPF packet is considered a replayed packet and 166 dropped. OSPF packets of different types may arrive out of order if 167 they are prioritized as recommended in [RFC3414]. 169 OSPF routers implementing this specification MUST use available 170 mechanisms to preserve the sequence number's strictly increasing 171 property for the deployed life of the OSPFv3 router (including cold 172 restarts). This is achieved by maintaining a boot count in non- 173 volatile storage and incrementing it each time the OSPF router loses 174 its prior sequence number state. The SNMPv3 snmpEngineBoots variable 175 [RFC4222] MAY be used for this purpose. However, maintaining a 176 separate boot count solely for OSPF sequence numbers has the 177 advantage of decoupling SNMP reinitialization and OSPF 178 reinitialization. Also, in the rare event that the lower order 32- 179 bit sequence number wraps, the boot count can be incremented to 180 preserve the strictly increasing property of the aggregate sequence 181 number. Hence, a separate OSPF boot count is RECOMMENDED. 183 3. OSPF Packet Extensions 185 The OSPF packet header includes an authentication type field, and 64- 186 bits of data for use by the appropriate authentication scheme 187 (determined by the type field). Authentication types 0, 1 and 2 are 188 defined [RFC2328]. This section of this defines Authentication type 189 TBD (3 is recommended). 191 When using this authentication scheme, the 64-bit Authentication 192 field in the OSPF packet header as defined in section D.3 of 193 [RFC2328] is changed as shown below. The sequence number is removed 194 and the Key ID is extended to 32 bits and moved to the former 195 position of the sequence number. 197 Additionally, the 64-bit sequence number is moved to the first 64- 198 bits following the OSPFv2 packet and is protected by the 199 authentication digest. These additional 64 bits or 8 octets are 200 included in the IP header length but not the OSPF header packet 201 length. 203 0 1 2 3 204 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | Version # | Type | Packet length | 207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 208 | Router ID | 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 210 | Area ID | 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 | Checksum | AuType | 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 214 | 0 | Auth Data Len | 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | Key ID | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | | 219 | OSPF Protocol Packet | 220 ~ ~ 221 | | 222 | | 223 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 224 | Sequence Number (Boot Count) | 225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 | Sequence Number (Strictly Increasing Packet Counter) | 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 | | 229 ~ Authentication Data ~ 230 | | 231 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 Figure 1 - Extended Sequence Number Packet Extensions 235 4. OSPF Packet Key Selection 237 This section describes how the proposed security solution selects 238 long-lived keys from key tables. [I-D.ietf-karp-crypto-key-table]. 239 Generally, a key used for OSPFv2 packet authentication should satisfy 240 the following requirements: 242 o For packet transmission, the key validity interval as defined by 243 SendLifetimeStart and SendLifetimeEnd must include the current 244 time. 246 o For packet reception, the key validity interval as defined by 247 AcceptLifetimeStart and AcceptLifetimeEnd must include the current 248 time. 250 o The key must be valid for the desired security algorithm. 252 In the remainder of this section, additional requirements for keys 253 are enumerated for different scenarios. 255 4.1. Key Selection for Unicast OSPF Packet Transmission 257 Assume that a router R1 tries to send a unicast OSPF packet from its 258 interface I1 to the interface I2 of a remote router R2 using security 259 protocol P via interface I at time T. First, consider the 260 circumstances where R1 and R2 are not connected with a virtual link. 261 R1 then needs to select a long long-lived symmetric key from its key 262 table. Because the key should be shared by both R1 and R2 to protect 263 the communication between I1 and I2, the key should satisfy the 264 following requirements: 266 o The Peers field is unused. OSPF authentication is interface 267 based. 269 o The Interfaces field includes the local IP address of the 270 interface for numbered interfaces or the MIB-II [RFC1213] ifIndex 271 for unnumbered interfaces. 273 o The Direction field is either "out" or "both". 275 o If multiple keys match the Interfaces field, the key with the most 276 recent SendLifetimeStart time will be selected. This will 277 facilitate graceful key rollover. 279 o The Key ID field in the OSPFv2 header (refer to figure 1) will be 280 set to the selected key's LocalKeyName. 282 When R1 and R2 are connected to a virtual link, the Interfaces field 283 must identify the virtual endpoint rather than the virtual link. 284 Since there may be virtual links to the same router, the transit area 285 ID must be part of the identifier. Hence, the key should satisfy the 286 following requirements: 288 o The Peers field is unused. OSPF authentication is interface 289 based. 291 o The Interfaces field includes both the virtual endpoint's OSPF 292 router ID and the transit area ID for the virtual link. 294 o The Direction field is either "out" or "both". 296 o If multiple keys match the Interfaces field, the key with the most 297 recent SendLifetimeStart time will be selected. This will 298 facilitate graceful key rollover. 300 o The Key ID field in the OSPFv2 header (refer to figure 1) will be 301 set to the selected key's LocalKeyName. 303 4.2. Key Selection for Multicast OSPF Packet Transmission 305 If a router R1 sends an OSPF packet from its interface I1 to a 306 multicast address (i.e., AllSPFRouters or AllDRouters), it needs to 307 select a key according to the following requirements: 309 o The Peers field is unused. OSPF authentication is interface 310 based. 312 o The Interfaces field includes the local IP address of the 313 interface for numbered interfaces or the MIB-II [RFC1213] ifIndex 314 for unnumbered interfaces. 316 o The Direction field is either "out" or "both". 318 o If multiple keys match the Interfaces field, the key with the most 319 recent SendLifetimeStart time will be selected. This will 320 facilitate graceful key rollover. 322 o The Key ID field in the OSPFv2 header (refer to figure 1) will be 323 set to the selected key's LocalKeyName. 325 4.3. Key Selection for OSPF Packet Reception 327 When Cryptographic Authentication is used, the ID of the 328 authentication key is included in the authentication field of the 329 OSPF packet header. Using this Key ID, it is straight forward for a 330 receiver to locate the corresponding key. The simple requirements 331 are: 333 o The interface on which the key was received is associated with the 334 key's interface. 336 o The Key ID obtained from the OSPFv2 packet header corresponds to 337 the neighbor's PeerKeyName. Since OSPFv2 keys are symmetric, the 338 LocalKeyName and PeerKeyName for OSPFv2 keys will be identical. 339 Hence, the Key ID will be used to select the correct local key. 341 o The Direction field is either "in" or "both". 343 5. Securing the IP header 345 This document updates the definition of the Apad constant, as it is 346 defined in [RFC5709], to include the IP source address from the IP 347 header of the OSPFv2 protocol packet. The overall cryptographic 348 authentication process defined in [RFC5709] remains unchanged. To 349 reduce the potential for confusion, this section minimizes the 350 repetition of text from RFC 5709 [RFC5709]. The changes are: 352 RFC 5709, Section 3.3, describes how the cryptographic authentication 353 must be computed. In RFC 5709, the First-Hash includes the OSPF 354 packet and Authentication Trailer. With this specification, the 64- 355 bit sequence number will be included in the First-Hash along with the 356 Authentication Trailer and OSPF packet. 358 RFC 5709, Section 3.3 also requires the OSPFv2 packet's 359 Authentication Trailer (which is the appendage described in RFC 2328, 360 Section D.4.3, Page 233, items (6)(a) and (6)(d)) to be filled with 361 the value Apad. Apad is a hexadecimal constant with the value 362 0x878FE1F3 repeated (L/4) times, where L is the length of the hash 363 being used and is measured in octets rather than bits. 365 OSPF routers sending OSPF packets must initialize Apad to the value 366 of the IP source address that would be used when sending an OSPFv2 367 packet, repeated L/4 times, where L is the length of the hash, 368 measured in octets. The basic idea is to incorporate the IP source 369 address from the IP header in the cryptographic authentication 370 computation so that any change of IP source address in a replayed 371 packet can be detected. 373 When an OSPF packet is received, implementations MUST initialize Apad 374 as the IP source address from the IP Header of the incoming OSPFv2 375 packet, repeated L/4 times, instead of the constant that's currently 376 defined in [RFC5709]. Besides changing the value of Apad, this 377 document does not introduce any other changes to the authentication 378 mechanism described in [RFC5709]. This would prevent all attacks 379 where a rogue OSPF router changes the IP source address of an OSPFv2 380 packet and replays it on the same multi-access interface or another 381 interface since the IP source address is now included in the 382 cryptographic hash computation and modification would result in the 383 OSPFv2 packet being dropped due to an authentication failure. 385 6. Mitigating Cross-Protocol Attacks 387 In order to prevent cross-protocol replay attacks for protocols 388 sharing common keys, the two octet OSPFv2 Cryptographic Protocol ID 389 is appended to the authentication key prior to use. Refer to IANA 390 Considerations (Section 8). 392 [RFC5709], Section 3.3 describes the mechanism to prepare the key 393 used in the hash computation. This document updates the sub section 394 "PREPARATION OF KEY" as follows: 396 The OSPFv2 Cryptographic Protocol ID is appended to the 397 Authentication Key (K) yielding a Protocol-Specific Authentication 398 Key (Ks). In this application, Ko is always L octets long. While 399 [RFC2104] supports a key that is up to B octets long, this 400 application uses L as the Ks length consistent with [RFC4822], 401 [RFC5310], and [RFC5709]. According to [FIPS-198], Section 3, keys 402 greater than L octets do not significantly increase the function 403 strength. Ks is computed as follows: 405 If the Protocol-Specific Authentication Key (Ks) is L octets long, 406 then Ko is equal to Ks. If the Protocol-Specific Authentication Key 407 (Ks) is more than L octets long, then Ko is set to H(Ks). If the 408 Protocol-Specific Authentication Key (Ks) is less than L octets long, 409 then Ko is set to the Protocol-Specific Authentication Key (Ks) with 410 zeros appended to the end of the Protocol-Specific Authentication Key 411 (Ks) such that Ko is L octets long. 413 Once the cryptographic key (Ko) used with the hash algorithm is 414 derived the rest of the authentication mechanism described in 415 [RFC5709] remains unchanged other than one detail that was 416 unspecified. When XORing Ko and Ipad of Opad, Ko MUST be padded with 417 zeros to the length of Ipad or Opad. It is expected that RFC 5709 418 [RFC5709] implementations perform this padding implicitly. 420 7. Security Considerations 422 This document rectifies the manual key management procedure that 423 currently exists within OSPFv2, as part of the Phase 1 of the KARP 424 Working Group. Therefore, only the OSPFv2 manual key management 425 mechanism is considered. Any solution that takes advantage of the 426 automatic key management mechanism is beyond the scope of this 427 document. 429 The proposed sequence number extension offers most of the benefits of 430 more complicated mechanisms without their attendant challenges. 431 There are, however, a couple drawbacks to this approach. First, it 432 requires the OSPF implementation to be able to save its boot count in 433 non-volatile storage. If the non-volatile storage is ever repaired 434 or upgraded such that the contents are lost or the OSPFv2 router is 435 replaced, the authentication keys MUST be changed to prevent replay 436 attacks. 438 Second, if a router is taken out of service completely (either 439 intentionally or due to a persistent failure), the potential exists 440 for reestablishment of an OSPFv2 adjacency by replaying the entire 441 OSPFv2 session establishment. However, this scenario is extremely 442 unlikely, since it would imply an identical OSPFv2 adjacency 443 formation packet exchange. Without adjacency formation, the replay 444 of OSPFv2 hello packets alone for an OSPFv2 router that has been 445 taken out of service should not result in any serious attack as the 446 only consequence is superfluous processing. Of course, this attack 447 could also be thwarted by changing the relevant manual keys. 449 This document also provides a solution to prevent certain denial of 450 service attacks that can be launched by changing the source address 451 in the IP header of an OSPFv2 protocol packet. 453 Using a single crypto sequence number can leave the router vulnerable 454 to a replay attack where it uses the same source IP address on two 455 different point-to-point unnumbered links. In such environments 456 where an attacker can actively tap the point-to-point links, its 457 recommended that the user employes different keys on each of those 458 unnumbered IP interfaces. 460 8. IANA Considerations 462 This document requests a new code point from the "OSPF Shortest Path 463 First (OSPF) Authentication Codes" registry: 465 o 3 - Cryptographic Authentication with Extended Sequence Numbers. 467 This document also requests a new code point from the "Authentication 468 Cryptographic Protocol ID" registry defined under "Keying and 469 Authentication for Routing Protocols (KARP) Parameters": 471 o 2 - OSPFv2. 473 9. References 475 9.1. Normative References 477 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 478 Requirement Levels", BCP 14, RFC 2119, March 1997. 480 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. 482 [RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M., 483 Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic 484 Authentication", RFC 5709, October 2009. 486 9.2. Informative References 488 [FIPS-198] 489 US National Institute of Standards & Technology, "The 490 Keyed-Hash Message Authentication Code (HMAC)", FIPS PUB 491 198 , March 2002. 493 [I-D.ietf-karp-crypto-key-table] 494 Housley, R., Polk, T., Hartman, S., and D. Zhang, 495 "Database of Long-Lived Symmetric Cryptographic Keys", 496 draft-ietf-karp-crypto-key-table-10 (work in progress), 497 December 2013. 499 [RFC1213] McCloghrie, K. and M. Rose, "Management Information Base 500 for Network Management of TCP/IP-based internets:MIB-II", 501 STD 17, RFC 1213, March 1991. 503 [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- 504 Hashing for Message Authentication", RFC 2104, 505 February 1997. 507 [RFC3414] Blumenthal, U. and B. Wijnen, "User-based Security Model 508 (USM) for version 3 of the Simple Network Management 509 Protocol (SNMPv3)", STD 62, RFC 3414, December 2002. 511 [RFC4222] Choudhury, G., "Prioritized Treatment of Specific OSPF 512 Version 2 Packets and Congestion Avoidance", BCP 112, 513 RFC 4222, October 2005. 515 [RFC4822] Atkinson, R. and M. Fanto, "RIPv2 Cryptographic 516 Authentication", RFC 4822, February 2007. 518 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 519 and M. Fanto, "IS-IS Generic Cryptographic 520 Authentication", RFC 5310, February 2009. 522 [RFC6039] Manral, V., Bhatia, M., Jaeggli, J., and R. White, "Issues 523 with Existing Cryptographic Protection Methods for Routing 524 Protocols", RFC 6039, October 2010. 526 [RFC6094] Bhatia, M. and V. Manral, "Summary of Cryptographic 527 Authentication Algorithm Implementation Requirements for 528 Routing Protocols", RFC 6094, February 2011. 530 [RFC6862] Lebovitz, G., Bhatia, M., and B. Weis, "Keying and 531 Authentication for Routing Protocols (KARP) Overview, 532 Threats, and Requirements", RFC 6862, March 2013. 534 [RFC6863] Hartman, S. and D. Zhang, "Analysis of OSPF Security 535 According to the Keying and Authentication for Routing 536 Protocols (KARP) Design Guide", RFC 6863, March 2013. 538 Authors' Addresses 540 Manav Bhatia 541 Ionos Networks 542 Bangalore, 543 India 545 Phone: 546 Email: manav@ionosnetworks.com 548 Sam Hartman 549 Painless Security 551 Email: hartmans@painless-security.com 553 Dacheng Zhang 554 Huawei Technologies co., LTD. 555 Beijing, 556 China 558 Phone: 559 Fax: 560 Email: zhangdacheng@huawei.com 561 URI: 563 Acee Lindem 564 Cisco 565 USA 567 Phone: 568 Email: acee@cisco.com