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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) ** Obsolete normative reference: RFC 5996 (Obsoleted by RFC 7296) -- Obsolete informational reference (is this intentional?): RFC 2898 (Obsoleted by RFC 8018) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPPM WG K. Pentikousis, Ed. 3 Internet-Draft EICT 4 Intended status: Standards Track Y. Cui 5 Expires: December 7, 2014 E. Zhang 6 Huawei Technologies 7 June 5, 2014 9 Network Performance Measurement for IPsec 10 draft-ietf-ippm-ipsec-03 12 Abstract 14 The O/TWAMP security mechanism requires that both the client and 15 server endpoints possess a shared secret. Since the currently- 16 standardized O/TWAMP security mechanism only supports a pre-shared 17 key mode, large scale deployment of O/TWAMP is hindered 18 significantly. At the same time, recent trends point to wider IKEv2 19 deployment which, in turn, calls for mechanisms and methods that 20 enable tunnel end-users, as well as operators, to measure one-way and 21 two-way network performance in a standardized manner. This document 22 discusses the use of keys derived from an IKEv2 SA as the shared key 23 in O/TWAMP. If the shared key can be derived from the IKEv2 SA, O/ 24 TWAMP can support certificate-based key exchange, which would allow 25 for more operational flexibility and efficiency. The key derivation 26 presented in this document can also facilitate automatic key 27 management. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on December 7, 2014. 46 Copyright Notice 48 Copyright (c) 2014 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 64 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 65 3. O/TWAMP Security . . . . . . . . . . . . . . . . . . . . . . 3 66 3.1. O/TWAMP-Control Security . . . . . . . . . . . . . . . . 4 67 3.2. O/TWAMP-Test Security . . . . . . . . . . . . . . . . . . 5 68 3.3. O/TWAMP Security Root . . . . . . . . . . . . . . . . . . 6 69 4. O/TWAMP for IPsec Networks . . . . . . . . . . . . . . . . . 6 70 4.1. Shared Key Derivation . . . . . . . . . . . . . . . . . . 6 71 4.2. Server Greeting Message Update . . . . . . . . . . . . . 7 72 4.3. Set-Up-Response Update . . . . . . . . . . . . . . . . . 9 73 4.4. O/TWAMP over an IPsec tunnel . . . . . . . . . . . . . . 10 74 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 75 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 76 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 77 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 78 8.1. Normative References . . . . . . . . . . . . . . . . . . 11 79 8.2. Informative References . . . . . . . . . . . . . . . . . 11 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 82 1. Introduction 84 The One-way Active Measurement Protocol (OWAMP) [RFC4656] and the 85 Two-Way Active Measurement Protocol (TWAMP) [RFC5357] can be used to 86 measure network performance parameters, such as latency, bandwidth, 87 and packet loss by sending probe packets and monitoring their 88 experience in the network. In order to guarantee the accuracy of 89 network measurement results, security aspects must be considered. 90 Otherwise, attacks may occur and the authenticity of the measurement 91 results may be violated. For example, if no protection is provided, 92 an adversary in the middle may modify packet timestamps, thus 93 altering the measurement results. 95 The currently-standardized O/TWAMP security mechanism [RFC4656] 96 [RFC5357] requires that endpoints (i.e. both the client and the 97 server) possess a shared secret. In today's network deployments, 98 however, the use of pre-shared keys is far from optimal. For 99 example, in wireless infrastructure networks, certain network 100 elements, which can be seen as the two endpoints from an O/TWAMP 101 perspective, support certificate-based security. For instance, 102 consider the case in which one wants to measure IP performance 103 between an eNB and SeGW. Both eNB and SeGW are 3GPP LTE nodes and 104 support certificate mode and IKEv2. Since the currently standardized 105 O/TWAMP security mechanism only supports pre-shared key mode, large 106 scale deployment of O/TWAMP is hindered significantly. Furthermore, 107 deployment and management of "shared secrets" for massive equipment 108 installation consumes a tremendous amount of effort and is prone to 109 human error. 111 With IKEv2 widely used, employing keys derived from IKEv2 SA as 112 shared key can be considered as a viable alternative. In mobile 113 telecommunication networks, the deployment rate of IPsec exceeds 95% 114 with respect to the LTE serving network. In older-technology 115 cellular networks, such as UMTS and GSM, IPsec use penetration is 116 lower, but still quite significant. If the shared key can be derived 117 from the IKEv2 SA, O/TWAMP can support cert-based key exchange and 118 make it more flexible in practice and more efficient. The use of 119 IKEv2 also makes it easier to extend automatic key management. In 120 general, O/TWAMP measurement packets can be transmitted inside the 121 IPsec tunnel, as it occurs with typical user traffic, or transmitted 122 outside the IPsec tunnel. This may depend on the operator's policy 123 and is orthogonal to the mechanism described in this document. 125 The remainder of this document is organized as follows. Section 3 126 summarizes O/TWAMP protocol operation with respect to security. 127 Section 4 presents a method of binding O/TWAMP and IKEv2 for network 128 measurements between the client and the server which both support 129 IKEv2. Finally, Section 5 discusses the security considerations 130 arising from the proposed mechanisms. 132 2. Terminology 134 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 135 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 136 document are to be interpreted as described in [RFC2119]. 138 3. O/TWAMP Security 140 Security for O/TWAMP-Control and O/TWAMP-Test are briefly reviewed in 141 the following subsections. 143 3.1. O/TWAMP-Control Security 145 O/TWAMP uses a simple cryptographic protocol which relies on 147 o AES in Cipher Block Chaining (AES-CBC) for confidentiality 149 o HMAC-SHA1 truncated to 128 bits for message authentication 151 Three modes of operation are supported in the OWAMP-Control protocol: 152 unauthenticated, authenticated, and encrypted. In addition to these 153 modes, the TWAMP-Control protocol also supports a mixed mode, i.e. 154 the TWAMP-Control protocol operates in encrypted mode while TWAMP- 155 Test protocol operates in unauthenticated mode. The authenticated, 156 encrypted and mixed modes require that endpoints possess a shared 157 secret, typically a passphrase. The secret key is derived from the 158 passphrase using a password-based key derivation function PBKDF2 159 (PKCS#5) [RFC2898]. 161 In the unauthenticated mode, the security parameters are left unused. 162 In the authenticated, encrypted and mixed modes, the security 163 parameters are negotiated during the control connection 164 establishment. 166 Figure 1 illustrates the initiation stage of the O/TWAMP-Control 167 protocol between a client and the server. In short, the client opens 168 a TCP connection to the server in order to be able to send O/TWAMP- 169 Control commands. The server responds with a Server Greeting, which 170 contains the Modes, Challenge, Salt, Count, and MBZ fields (see 171 Section 3.1 of [RFC4656]). If the client-preferred mode is 172 available, the client responds with a Set-Up- Response message, 173 wherein the selected Mode, as well as the KeyID, Token and Client IV 174 are included. The Token is the concatenation of a 16-octet 175 Challenge, a 16-octet AES Session-key used for encryption, and a 176 32-octet HMAC-SHA1 Session-key used for authentication. The Token is 177 encrypted using AES-CBC. 179 +--------+ +--------+ 180 | Client | | Server | 181 +--------+ +--------+ 182 | | 183 |<---- TCP Connection ----->| 184 | | 185 |<---- Greeting message ----| 186 | | 187 |----- Set-Up-Response ---->| 188 | | 189 |<---- Server-Start --------| 190 | | 192 Figure 1: Initiation of O/TWAMP-Control 194 Encryption uses a key derived from the shared secret associated with 195 KeyID. In the authenticated, encrypted and mixed modes, all further 196 communication is encrypted using the AES Session-key and 197 authenticated with the HMAC Session-key. After receiving Set-Up- 198 Response the server responds with a Server-Start message containing 199 Server-IV. The client encrypts everything it transmits through the 200 just-established O/TWAMP-Control connection using stream encryption 201 with Client- IV as the IV. Correspondingly, the server encrypts its 202 side of the connection using Server-IV as the IV. The IVs themselves 203 are transmitted in cleartext. Encryption starts with the block 204 immediately following that containing the IV. 206 The AES Session-key and HMAC Session-key are generated randomly by 207 the client. The HMAC Session-key is communicated along with the AES 208 Session-key during O/TWAMP-Control connection setup. The HMAC 209 Session-key is derived independently of the AES Session-key. 211 3.2. O/TWAMP-Test Security 213 The O/TWAMP-Test protocol runs over UDP, using the client and server 214 IP and port numbers that were negotiated during the Request-Session 215 exchange. O/TWAMP- Test has the same mode with O/TWAMP-Control and 216 all O/TWAMP-Test sessions inherit the corresponding O/TWAMP-Control 217 session mode except when operating in mixed mode. 219 The O/TWAMP-Test packet format is the same in authenticated and 220 encrypted modes. The encryption and authentication operations are, 221 however, different. Similarly with the respective O/TWAMP-Control 222 session, each O/TWAMP-Test session has two keys: an AES Session-key 223 and an HMAC Session-key. However, there is a difference in how the 224 keys are obtained: 226 O/TWAMP-Control: the keys are generated by the client and 227 communicated to the server during the control connection 228 establishment with the Set-Up-Response message (as part of 229 the Token). 231 O/TWAMP-Test: the keys are derived from the O/TWAMP-Control keys and 232 the session identifier (SID), which serve as inputs of the 233 key derivation function (KDF). The O/TWAMP-Test AES Session- 234 key is generated using the O/TWAMP- Control AES Session-key, 235 with the 16-octet session identifier (SID), for encrypting 236 and decrypting the packets of the particular O/TWAMP-Test 237 session. The O/TWAMP-Test HMAC Session-key is generated 238 using the O/TWAMP-Control HMAC Session-key, with the 16-octet 239 session identifier (SID), for authenticating the packets of 240 the particular O/TWAMP-Test session. 242 3.3. O/TWAMP Security Root 244 As discussed above, the AES Session-key and HMAC Session-key used by 245 the O/TWAMP-Test protocol are derived from the AES Session-key and 246 HMAC Session-key which are used in O/TWAMP-Control protocol. The AES 247 Session-key and HMAC Session-key used in the O/TWAMP-Control protocol 248 are generated randomly by the client, and encrypted with the shared 249 secret associated with KeyID. Therefore, the security root is the 250 shared secret key. Thus, for large deployments, key provision and 251 management may become overly complicated. Comparatively, a 252 certificate-based approach using IKEv2 can automatically manage the 253 security root and solve this problem, as we explain in Section 4. 255 4. O/TWAMP for IPsec Networks 257 This section presents a method of binding O/TWAMP and IKEv2 for 258 network measurements between a client and a server which both support 259 IPsec. In short, the shared key used for securing O/TWAMP traffic is 260 derived using IKEv2 [RFC5996]. 262 4.1. Shared Key Derivation 264 In the authenticated, encrypted and mixed modes, the shared secret 265 key can be derived from the IKEv2 Security Association (SA). Note 266 that we explicitly opt to derive the shared secret key from the IKEv2 267 SA, rather than the child SA, since the use case whereby an IKEv2 SA 268 can be created without generating any child SA is possible [RFC6023]. 270 If the shared secret key is derived from the IKEv2 SA, SKEYSEED must 271 be generated first. SKEYSEED and its derivatives MUST be computed as 272 per [RFC5996], where prf is a pseudorandom function: 274 SKEYSEED = prf( Ni | Nr, g^ir ) 276 Ni and Nr are, respectively, the initiator and responder nonces, 277 which are negotiated during the initial exchange (see Section 1.2 of 278 [RFC5996]). g^ir is the shared secret from the ephemeral Diffie- 279 Hellman exchange and is represented as a string of octets. 281 The shared secret key MUST be generated as follows: 283 Shared secret key = PRF( SKEYSEED, "IPPM" ) 285 Wherein the string "IPPM" comprises four ASCII characters. It is 286 recommended that the shared secret key is derived in the IPsec layer. 287 This way, the IPsec keying material is not exposed to the O/TWAMP 288 client. Note, however, that the interaction between the O/TWAMP and 289 IPsec layers is host-internal and implementation-specific. 290 Therefore, this is clearly outside the scope of this document, which 291 focuses on the interaction between the O/TWAMP client and server. 292 That said, one possible way could be the following: at the client 293 side, the IPSec layer can perform a lookup in the Security 294 Association Database (SAD) using the IP address of the server and 295 thus match the corresponding IKEv2 SA. At the server side, the IPSec 296 layer can look up the corresponding IKEv2 SA by using the SPIs sent 297 by the client, and therefore extract the shared secret key. In case 298 that both client and server do support IKEv2 but there is no current 299 IKEv2 SA, two alternative ways could be considered. First, the O/ 300 TWAMP client initiates the establishment of the IKEv2 SA, logs this 301 operation, and selects the mode which supports IKEv2. Alternatively, 302 the O/TWAMP client does not initiate the establishment of the IKEv2 303 SA, logs an error for operational management purposes, and proceeds 304 with the modes defined in [RFC4656][RFC5618]. Again, although both 305 alternatives are feasible, they are in fact implementation-specific. 307 If rekeying for the IKEv2 SA or deletion of the IKEv2 SA occurs, the 308 corresponding shared secret key generated from the SA can continue to 309 be used until the lifetime of the shared secret key expires. 311 4.2. Server Greeting Message Update 313 To achieve a binding association between the key generated from IKEv2 314 and the O/TWAMP shared secret key, Server Greeting Message should be 315 updated as in Figure 2. 317 0 1 2 3 318 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 1 319 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 320 | | 321 | Unused (12 octets) | 322 | | 323 |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 | Modes | 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 326 | | 327 | Challenge (16 octets) | 328 | | 329 | | 330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 331 | | 332 | Salt (16 octets) | 333 | | 334 | | 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 | Count (4 octets) | 337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 338 | | 339 | MBZ (12 octets) | 340 | | 341 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 343 Figure 2: Server Greeting format 345 The Modes field in Figure 2 will need to allow for support of key 346 derivation as discussed in Section 4.1. As such, the Modes value 347 extension MUST be supported by implementations compatible with this 348 document, indicating support for deriving shared key from IKEv2 SA. 349 Three new Modes including authenticated mode over IKEv2(IANA.TBA.O/ 350 TWAMP.IKEAuth),encrypted mode over IKEv2(IANA.TBA.O/TWAMP.IKEEnc) and 351 mixed mode over IKEv2(IANA.TBA.TWAMP.IKEMix) are proposed. 353 Authenticated mode over IKEv2 means that the client and server 354 operate in authenticated mode with the shared secret key derived from 355 IKEv2 SA. Encrypted mode over IKEv2 means that the client and server 356 operate in encrypted mode with the shared secret key derived from 357 IKEv2 SA. Mixed mode over IKEv2 means that the client and server 358 operate in encrypted mode for the O/TWAMP-Control protocol while 359 operating in unauthenticated mode for the O/TWAMP-Test protocol with 360 shared secret key derived from IKEv2 SA. 362 The choice of this set of Modes values poses the least backwards 363 compatibility problems to existing O/TWAMP clients. Robust client 364 implementations of [RFC4656] would disregard the fact that the first 365 29 Modes bits in the Server Greeting is set. If the server supports 366 other Modes, as one would assume, the client would then indicate any 367 of the Modes defined in [RFC4656] and effectively indicate that it 368 does not support key derivation from IKEv2. At this point, the 369 Server would need to use the Modes defined in [RFC4656] only. 371 4.3. Set-Up-Response Update 373 The Set-Up-Response Message should be updated as in Figure 3. 375 0 1 2 3 376 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 1 377 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 378 | Mode | 379 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 380 | | 381 | Key ID (80 octets) | 382 | | 383 | | 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | | 386 | Token (16 octets) | 387 | | 388 | | 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 | | 391 | Client-IV (12 octets) | 392 | | 393 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 Figure 3: Set-Up-Response Message 397 The Security Parameter Index (SPI)(see [RFC4301] [RFC5996]) can 398 uniquely identify the Security Association (SA). If the client 399 supports the derivation of shared secret key from IKEv2 SA, it will 400 choose the corresponding mode value and carry SPIi and SPIr in the 401 Key ID field. SPIi and SPIr are included in the Key ID field of Set- 402 Up- Response Message to indicate the IKEv2 SA from which the O/TWAMP 403 shared secret key derived from. The length of SPI is 4 octets. 404 Therefore, the first 4 octets of Key ID field carry SPIi and the 405 second 4 octets carry SPIr. The remaining bits of the Key ID field 406 are set to zero. 408 A O/TWAMP server which supports the specification of this document, 409 can obtain the SPIi and SPIr from the first 8 octets and ignore the 410 rest octets of the Key ID field. Then, the client and the server can 411 derive the shared secret key based on the mode value and SPI. If the 412 O/TWAMP server cannot find the IKEv2 SA corresponding to the SPIi and 413 SPIr received, it MUST log the event for operational management 414 purposes. In addition, the O/TWAMP server SHOULD set the Accept 415 field of the Server-Start message to the value 6 to indicate that 416 server is not willing to conduct further transactions in this O/ 417 TWAMP-Control session since it can not find the corresponding IKEv2 418 SA. 420 4.4. O/TWAMP over an IPsec tunnel 422 IPsec AH [RFC4302] and ESP [RFC4303] provide confidentiality and 423 data integrity to IP datagrams. Thus and IPsec tunnel can be used to 424 provide the protection needed for O/TWAMP Control and Test packets, 425 even if the peers choose the unauthenticated mode of operation. If 426 the two endpoints are already connected through an IPSec tunnel it is 427 RECOMMENDED that the O/TWAMP measurement packets are forwarded over 428 the IPSec tunnel if the peers choose the unauthenticated mode in 429 order to ensure authenticity and security. 431 5. Security Considerations 433 As the shared secret key is derived from the IKEv2 SA, the key 434 derivation algorithm strength and limitations are as per [RFC5996]. 435 The strength of a key derived from a Diffie-Hellman exchange using 436 any of the groups defined here depends on the inherent strength of 437 the group, the size of the exponent used, and the entropy provided by 438 the random number generator employed. The strength of all keys and 439 implementation vulnerabilities, particularly Denial of Service (DoS) 440 attacks are as defined in [RFC5996]. 442 As a more general note, the IPPM community may want to revisit the 443 arguments listed in [RFC4656], Sec. 6.6. Other widely-used Internet 444 security mechanisms, such as TLS and DTLS, may also be considered for 445 future use over and above of what is already specified in [RFC4656] 446 [RFC5357]. 448 6. IANA Considerations 450 IANA will need to allocate additional values for the Modes options 451 presented in this document. 453 7. Acknowledgments 455 Emily Bi contributed to an earlier version of this document. 457 We thank Eric Chen, Yakov Stein, Brian Trammell, and John Mattsson 458 for their comments on this draft, and Al Morton for the discussion 459 and pointers to related earlier work in IPPM WG. 461 8. References 463 8.1. Normative References 465 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 466 Requirement Levels", BCP 14, RFC 2119, March 1997. 468 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, December 469 2005. 471 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 472 4303, December 2005. 474 [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. 475 Zekauskas, "A One-way Active Measurement Protocol 476 (OWAMP)", RFC 4656, September 2006. 478 [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. 479 Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", 480 RFC 5357, October 2008. 482 [RFC5618] Morton, A. and K. Hedayat, "Mixed Security Mode for the 483 Two-Way Active Measurement Protocol (TWAMP)", RFC 5618, 484 August 2009. 486 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 487 "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 488 5996, September 2010. 490 8.2. Informative References 492 [RFC2898] Kaliski, B., "PKCS #5: Password-Based Cryptography 493 Specification Version 2.0", RFC 2898, September 2000. 495 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 496 Internet Protocol", RFC 4301, December 2005. 498 [RFC6023] Nir, Y., Tschofenig, H., Deng, H., and R. Singh, "A 499 Childless Initiation of the Internet Key Exchange Version 500 2 (IKEv2) Security Association (SA)", RFC 6023, October 501 2010. 503 Authors' Addresses 504 Kostas Pentikousis (editor) 505 EICT GmbH 506 EUREF-Campus Haus 13 507 Torgauer Strasse 12-15 508 10829 Berlin 509 Germany 511 Email: k.pentikousis@eict.de 513 Yang Cui 514 Huawei Technologies 515 Otemachi First Square 1-5-1 Otemachi 516 Chiyoda-ku, Tokyo 100-0004 517 Japan 519 Email: cuiyang@huawei.com 521 Emma Zhang 522 Huawei Technologies 523 Huawei Building, Q20, No.156, Rd. BeiQing 524 Haidian District , Beijing 100095 525 P. R. China 527 Email: emma.zhanglijia@huawei.com