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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (July 4, 2007) is 5435 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Looks like a reference, but probably isn't: '12' on line 301 ** Obsolete normative reference: RFC 4346 (ref. 'TLS') (Obsoleted by RFC 5246) ** Obsolete normative reference: RFC 4366 (ref. 'TLS-EXT') (Obsoleted by RFC 5246, RFC 6066) -- Obsolete informational reference (is this intentional?): RFC 3588 (ref. 'Diameter') (Obsoleted by RFC 6733) == Outdated reference: draft-ietf-emu-eap-gpsk has been published as RFC 5433 == Outdated reference: draft-ietf-eap-keying has been published as RFC 5247 -- Obsolete informational reference (is this intentional?): RFC 4306 (Obsoleted by RFC 5996) Summary: 3 errors (**), 0 flaws (~~), 3 warnings (==), 10 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 TLS Working Group Y. Nir 3 Internet-Draft Y. Sheffer 4 Intended status: Standards Track Check Point 5 Expires: January 5, 2008 H. Tschofenig 6 NSN 7 P. Gutmann 8 University of Auckland 9 July 4, 2007 11 TLS using EAP Authentication 12 draft-nir-tls-eap-01.txt 14 Status of this Memo 16 By submitting this Internet-Draft, each author represents that any 17 applicable patent or other IPR claims of which he or she is aware 18 have been or will be disclosed, and any of which he or she becomes 19 aware will be disclosed, in accordance with Section 6 of BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF), its areas, and its working groups. Note that 23 other groups may also distribute working documents as Internet- 24 Drafts. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 The list of current Internet-Drafts can be accessed at 32 http://www.ietf.org/ietf/1id-abstracts.txt. 34 The list of Internet-Draft Shadow Directories can be accessed at 35 http://www.ietf.org/shadow.html. 37 This Internet-Draft will expire on January 5, 2008. 39 Copyright Notice 41 Copyright (C) The IETF Trust (2007). 43 Abstract 45 This document describes an extension to the TLS protocol to allow TLS 46 clients to authenticate with legacy credentials using the Extensible 47 Authentication Protocol (EAP). 49 This work follows the example of IKEv2, where EAP has been added to 50 the IKEv2 protocol to allow clients to use different credentials such 51 as passwords, token cards, and shared secrets. 53 When TLS is used with EAP, additional records are sent after the 54 ChangeCipherSpec protocol message and before the Finished message, 55 effectively creating an extended handshake before the application 56 layer data can be sent. Each EapMsg handshake record contains 57 exactly one EAP message. Using EAP for client authentication allows 58 TLS to be used with various AAA back-end servers such as RADIUS or 59 Diameter. 61 TLS with EAP may be used for securing a data connection such as HTTP 62 or POP3. We believe it has three main benefits: 63 o The ability of EAP to work with backend servers can remove that 64 burden from the application layer. 65 o Moving the user authentication into the TLS handshake protects the 66 presumably less secure application layer from attacks by 67 unauthenticated parties. 68 o Using mutual authentication methods within EAP can help thwart 69 certain classes of phishing attacks. 71 Table of Contents 73 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 74 1.1. EAP Applicability . . . . . . . . . . . . . . . . . . . . 5 75 1.2. Conventions Used in This Document . . . . . . . . . . . . 5 76 2. Operating Environment . . . . . . . . . . . . . . . . . . . . 6 77 3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 78 3.1. The tee_supported Extension . . . . . . . . . . . . . . . 8 79 3.2. The InterimAuth Handshake Message . . . . . . . . . . . . 8 80 3.3. The EapMsg Handshake Message . . . . . . . . . . . . . . . 8 81 3.4. Calculating the Finished message . . . . . . . . . . . . . 9 82 4. Security Considerations . . . . . . . . . . . . . . . . . . . 10 83 4.1. InterimAuth vs. Finished . . . . . . . . . . . . . . . . . 10 84 4.2. Identity Protection . . . . . . . . . . . . . . . . . . . 10 85 4.3. Mutual Authentication . . . . . . . . . . . . . . . . . . 11 86 5. Performance Considerations . . . . . . . . . . . . . . . . . . 12 87 6. Operational Considerations . . . . . . . . . . . . . . . . . . 13 88 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 89 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15 90 9. Changes from Previous Versions . . . . . . . . . . . . . . . . 16 91 9.1. Changes in version -01 . . . . . . . . . . . . . . . . . . 16 92 9.2. Changes from the protocol model draft . . . . . . . . . . 16 93 10. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 17 94 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 95 11.1. Normative References . . . . . . . . . . . . . . . . . . . 18 96 11.2. Informative References . . . . . . . . . . . . . . . . . . 18 97 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 98 Intellectual Property and Copyright Statements . . . . . . . . . . 21 100 1. Introduction 102 This document describes a new extension to [TLS]. This extension 103 allows a TLS client to authenticate using [EAP] instead of performing 104 the authentication at the application level. The extension follows 105 [TLS-EXT]. For the remainder of this document we will refer to this 106 extension as TEE (TLS with EAP Extension). 108 TEE extends the TLS handshake beyond the regular setup, to allow the 109 EAP protocol to run between the TLS server (called an "authenticator" 110 in EAP) and the TLS client (called a "supplicant"). This allows the 111 TLS architecture to handle client authentication before exposing the 112 server application software to an unauthenticated client. In doing 113 this, we follow the approach taken for IKEv2 in [RFC4306]. However, 114 similar to regular TLS, we protect the user identity by only sending 115 the client identity after the server has authenticated. In this our 116 solution differs from that of IKEv2. 118 Currently used applications that rely on non-certificate user 119 credentials use TLS to authenticate the server only. After that, the 120 application takes over, and presents a login screen where the user is 121 expected to present their credentials. 123 This creates several problems. It allows a client to access the 124 application before authentication, thus creating a potential for 125 anonymous attacks on non-hardened applications. Additionally, web 126 pages are not particularly well suited for long shared secrets and 127 for interfacing with certain devices such as USB tokens. 129 TEE allows full mutual authentication to occur for all these 130 applications within the TLS exchange. The application receives 131 control only when the user is identified and authenticated. The 132 authentication can be built into the server infrastructure by 133 connecting to an AAA server. The client side can be integrated into 134 client software such as web browsers and mail clients. An EAP 135 infrastructure is already built into some operating systems providing 136 a user interface for each authentication method within EAP. 138 We intend TEE to be used for various protocols that use TLS such as 139 HTTPS, in cases where certificate based client authentication is not 140 practical. This includes web-based mail services, online banking, 141 premium content websites and mail clients. 143 Another class of applications that may see benefit from TEE are TLS 144 based VPN clients used as part of so-called "SSL VPN" products. No 145 such client protocols have so far been standardized. 147 1.1. EAP Applicability 149 Section 1.3 of [EAP] states that EAP is only applicable for network 150 access authentication, rather than for "bulk data transfer". It then 151 goes on to explain why the transport properties of EAP indeed make it 152 unsuitable for bulk data transfer, e.g. for large file transport. 153 Our proposed use of EAP falls squarely within the applicability as 154 defined, since we make no further use of EAP beyond access 155 authentication. 157 1.2. Conventions Used in This Document 159 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 160 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 161 document are to be interpreted as described in [RFC2119]. 163 2. Operating Environment 165 TEE will work between a client application and a server application, 166 performing either client authentication or mutual authentication 167 within the TLS exchange. 169 Client Server 170 +-------------------------+ +------------------------+ 171 | |GUI| | Client | |TLS+-+-----+-+TLS| |Server | | 172 | +-^-+ |Software| +-^-+ | +-+-^-+ |Application | | 173 | | +--------+ | | | | |Software | | 174 | | | | | | +------------+ | 175 | +-v----------------v-+ | | | | 176 | | EAP | | +---|--------------------+ 177 | | Infrastructure | | | 178 | +--------------------+ | | +--------+ 179 +-------------------------+ | | AAA | 180 | | Server | 181 +----- | 182 +--------+ 184 The above diagram shows the typical deployment. The client has 185 software that either includes a UI for some EAP methods, or else is 186 able to invoke some operating system EAP infrastructure that takes 187 care of the user interaction. The server is configured with the 188 address and protocol of the AAA server. Typically the AAA server 189 communicates using the RADIUS protocol with EAP ([RADIUS] and 190 [RAD-EAP]), or the Diameter protocol ([Diameter] and [Dia-EAP]). 192 As stated in the introduction, we expect TEE to be used in both 193 browsers and applications. Further uses may be authentication and 194 key generation for other protocols, and tunneling clients, which so 195 far have not been standardized. 197 3. Protocol Overview 199 The TEE extension defines the following: 200 o A new extension type called tee_supported, used to indicate that 201 the communicating application (either client or server) supports 202 this extension. 203 o A new message type for the handshake protocol, called InterimAuth, 204 which is used to sign previous messages. 205 o A new message type for the handshake protocol, called EapMsg, 206 which is used to carry a single EAP message. 208 The diagram below outlines the protocol structure. For illustration 209 purposes only, we use the GPSK EAP method [EAP-GPSK]. 211 Client Server 212 ------ ------ 214 ClientHello(*) --------> 215 ServerHello(*) 216 (Certificate) 217 ServerKeyExchange 218 EapMsg(Identity-Request) 219 <-------- ServerHelloDone 220 ClientKeyExchange 221 (CertificateVerify) 222 ChangeCipherSpec 223 InterimAuth 224 EapMsg(Identity-Reply) --------> 225 ChangeCipherSpec 226 InterimAuth 227 EapMsg(GPSK-Request) 228 <-------- 229 EapMsg(GPSK-Reply) --------> 230 EapMsg(GPSK-Request) 231 <-------- 232 EapMsg(GPSK-Reply) --------> 233 EapMsg(Success) 234 <-------- Finished 235 Finished --------> 237 (*) The ClientHello and ServerHello include the tee_supported 238 extension to indicate support for TEE 240 The client indicates in the first message its support for TEE. The 241 server sends an EAP identity request in the reply. The client sends 242 the identity reply after the handshake completion. The EAP request- 243 response sequence continues until the client is either authenticated 244 or rejected. 246 3.1. The tee_supported Extension 248 The tee_supported extension is a ClientHello and ServerHello 249 extension as defined in section 2.3 of [TLS-EXT]. The extension_type 250 field is TBA by IANA. The extension_data is zero-length. 252 3.2. The InterimAuth Handshake Message 254 The InterimAuth message is identical in syntax to the Finished 255 message described in section 7.4.9 of [TLS]. It is calculated in 256 exactly the same way. 258 The semantics, however, are somewhat different. The "Finished" 259 message indicates that application data may now be sent. The 260 "InterimAuth" message does not indicate this. Instead, further 261 handshake messages are needed. 263 The HandshakeType value for the InterimAuth handshake message is TBA 264 by IANA. 266 3.3. The EapMsg Handshake Message 268 The EapMsg handshake message carries exactly one EAP message as 269 defined in [EAP]. 271 The HandshakeType value for the EapMsg handshake message is TBA by 272 IANA. 274 The EapMsg message is used to tunnel EAP messages between the 275 authentication server, which may be co-located with the TLS server, 276 or else may be a separate AAA server, and the supplicant, which is 277 co-located with the TLS client. TLS on either side receives the EAP 278 data from the EAP infrastructure, and treats it as opaque. TLS does 279 not make any changes to the EAP payload or make any decisions based 280 on the contents of an EapMsg handshake message. 282 Note that it is expected that the authentication server notifies the 283 TLS server about authentication success or failure, and so TLS need 284 not inspect the eap_payload within the EapMsg to detect success or 285 failure. 287 struct { 288 opaque eap_payload[4..65535]; 289 } EapMsg; 291 eap_payload is defined in section 4 of RFC 3748. It includes 292 the Code, Identifier, Length and Data fields of the EAP 293 packet. 295 3.4. Calculating the Finished message 297 If the EAP method is key-generating (see [I-D.ietf-eap-keying]), the 298 Finished message is calculated as follows: 300 struct { 301 opaque verify_data[12]; 302 } Finished; 304 verify_data 305 PRF(MSK, finished_label, MD5(handshake_messages) + 306 SHA-1(handshake_messages)) [0..11]; 308 The finished_label and the PRF are as defined in section 7.4.9 of 309 [TLS]. 311 The handshake_messages field, unlike regular TLS, does not sign all 312 the data in the handshake. Instead it signs all the data that has 313 not been signed by the previous InterimAuth message. The 314 handshake_messages field includes all of the octets beginning with 315 and including the InterimAuth message, up to but not including this 316 Finished message. This is the concatenation of all the Handshake 317 structures exchanged thus far, and not yet signed, as defined in 318 section 7.4 of [TLS]and in this document. 320 The Master Session Key (MSK) is derived by the AAA server and by the 321 client if the EAP method is key-generating. On the server-side, it 322 is typically received from the AAA server over the RADIUS or Diameter 323 protocol. On the client-side, it is passed to TLS by some other 324 method. 326 If the EAP method is not key-generating, then the master_secret is 327 used to sign the messages instead of the MSK. For a discussion on 328 the use of such methods, see Section 4.1. 330 4. Security Considerations 332 4.1. InterimAuth vs. Finished 334 In regular TLS, the Finished message provides two functions: it signs 335 all preceding messages, and it signals that application data can now 336 be sent. In TEE, it only signs those messages that have not yet been 337 signed. 339 Some EAP methods, such as EAP-TLS, EAP-IKEv2 and EAP-SIM generate 340 keys in addition to authenticating clients. Such methods are said to 341 be resistant to man-in-the-middle (MITM) attacks as discussed in 342 [MITM]. Such methods are called key-generating methods. 344 To realize the benefit of such methods, we need to verify the key 345 that was generated within the EAP method. This is referred to as the 346 MSK in EAP. In TEE, the InterimAuth message signs all previous 347 messages with the master_secret, just like the Finished message in 348 regular TLS. The Finished message signs the rest of the messages 349 using the MSK if such exists. If not, then the messages are signed 350 with the master_secret as in regular TLS. 352 The need for signing twice arises from the fact that we need to use 353 both the master_secret and the MSK. It was possible to use just one 354 Finished record and blend the MSK into the master_secret. However, 355 this would needlessly complicate the protocol and make security 356 analysis more difficult. Instead, we have decided to follow the 357 example of IKEv2, where two AUTH payloads are exchanged. 359 It should be noted that using non-key-generating methods may expose 360 the client to a MITM attack if the same method and credentials are 361 used in some other situation, in which the EAP is done outside of a 362 protected tunnel with an authenticated server. Unless it can be 363 determined that the EAP method is never used in such a situation, 364 non-key-generating methods SHOULD NOT be used. This issue is 365 discussed extensively in [Compound-Authentication]. 367 4.2. Identity Protection 369 Unlike [TLS-PSK], TEE provides identity protection for the client. 370 The client's identity is hidden from a passive eavesdropper using TLS 371 encryption. Active attacks are discussed in Section 4.3. 373 We could save one round-trip by having the client send its identity 374 within the Client Hello message. This is similar to TLS-PSK. 375 However, we believe that identity protection is a worthy enough goal, 376 so as to justify the extra round-trip. 378 4.3. Mutual Authentication 380 In order to achieve our security goals, we need to have both the 381 server and the client authenticate. Client authentication is 382 obviously done using the EAP method. The server authentication can 383 be done in either of two ways: 384 1. The client can verify the server certificate. This may work well 385 depending on the scenario, but implies that the client or its 386 user can recognize the right DN or alternate name, and 387 distinguish it from plausible alternatives. The introduction to 388 [I.D.Webauth-phishing] shows that at least in HTTPS, this is not 389 always the case. 390 2. The client can use a mutually authenticated (MA) EAP method such 391 as GPSK. In this case, server certificate verification does not 392 matter, and the TLS handshake may as well be anonymous. Note 393 that in this case, the client identity is sent to the server 394 before server authentication. 396 To summarize: 397 o Clients MUST NOT propose anonymous ciphersuites, unless they 398 support MA EAP methods. 399 o Clients MUST NOT accept non-MA methods if the ciphersuite is 400 anonymous. 401 o Clients MUST NOT accept non-MA methods if they are not able to 402 verify the server credentials. Note that this document does not 403 define what verification involves. If the server DN is known and 404 stored on the client, verifying certificate signature and checking 405 revocation may be enough. For web browsers, the case is not as 406 clear cut, and MA methods SHOULD be used. 408 5. Performance Considerations 410 Regular TLS adds two round-trips to a TCP connection. However, 411 because of the stream nature of TCP, the client does not really need 412 to wait for the server's Finished message, and can begin sending 413 application data immediately after its own Finished message. In 414 practice, many clients do so, and TLS only adds one round-trip of 415 delay. 417 TEE adds as many round-trips as the EAP method requires. For 418 example, EAP-MD5 requires 1 round-trip, while EAP-GPSK requires 2 419 round-trips. Additionally, the client MUST wait for the EAP-Success 420 message before sending its own Finished message, so we need at least 421 3 round-trips for the entire handshake. The best a client can do is 422 two round-trips plus however many round-trips the EAP method 423 requires. 425 It should be noted, though, that these extra round-trips save 426 processing time at the application level. Two extra round-trips take 427 a lot less time than presenting a log-in web page and processing the 428 user's input. 430 It should also be noted, that TEE reverses the order of the Finished 431 messages. In regular TLS the client sends the Finished message 432 first. In TEE it is the server that sends the Finished message 433 first. This should not affect performance, and it is clear that the 434 client may send application data immediately after the Finished 435 message. 437 6. Operational Considerations 439 Section 4.3 defines a dependency between the TLS state and the EAP 440 state in that it mandates that certain EAP methods should not be used 441 with certain TLS ciphersuites. To avoid such dependencies, there are 442 two approaches that implementations can take. They can either not 443 use any anonymous ciphersuites, or else they can use only MA EAP 444 methods. 446 Where certificate validation is problematic, such as in browser-based 447 HTTPS, we recommend the latter approach. 449 In cases where the use of EAP within TLS is not known before opening 450 the connection, it is necessary to consider the implications of 451 requiring the user to type in credentials after the connection has 452 already started. TCP sessions may time out, because of security 453 considerations, and this may lead to session setup failure. 455 7. IANA Considerations 457 IANA is asked to assign an extension type value from the 458 "ExtensionType Values" registry for the tee_supported extension. 460 IANA is asked to assign two handshake message types from the "TLS 461 HandshakeType Registry", one for "EapMsg" and one for "InterimAuth". 463 8. Acknowledgments 465 The authors would like to thank Josh Howlett for his comments. 467 The TLS Inner Application Extension work ([TLS/IA]) has inspired the 468 authors to create this simplified work. TLS/IA provides a somewhat 469 different approach to integrating non-certificate credentials into 470 the TLS protocol, in addition to several other features available 471 from the RADIUS namespace. 473 The authors would also like to thank the various contributors to 474 [RFC4306] whose work inspired this one. 476 9. Changes from Previous Versions 478 9.1. Changes in version -01 480 o Changed the construction of the Finished message 481 o Replaced MS-CHAPv2 with GPSK in examples. 482 o Added open issues section. 483 o Added reference to [Compound-Authentication] 484 o Fixed reference to MITM attack 486 9.2. Changes from the protocol model draft 488 o Added diagram for EapMsg 489 o Added discussion of EAP applicability 490 o Added discussion of mutually-authenticated EAP methods vs other 491 methods in the security considerations. 492 o Added operational considerations. 493 o Other minor nits. 495 10. Open Issues 497 Some have suggested that since the protocol is identical to regular 498 TLS up to the InterimAuth message, we should call that the Finished 499 message, and call the last message in the extended handshake 500 something like "EapFinished". This has the advantage that the 501 construction of Finished is already well defined and will not change. 502 However, the Finished message has a specific meaning as indicated by 503 its name. It means that the handshake is over and that application 504 data can now be sent. This is not true of what is in this draft 505 called InterimAuth. We'd like the opinions of reviewrs about this 506 issue. 508 The MSK from the EAP exchange is only used to sign the Finished 509 message. It is not used again in the data encryption. In this we 510 followed the example of IKEv2. The reason is that TLS already has 511 perfectly good ways of exchanging keys, and we do not need this 512 capability from EAP methods. Also, using the MSK in keys would 513 require an additional ChangeCipherSpec and would complicate the 514 protocol. We'd like the opinions of reviewrs about this issue. 516 Another response we got was that we should have a MUST requirement 517 that only mutually authenticated and key-generating methods be used 518 in TEE. This would simplify the security considerations section. 519 While we agree that this is a good idea, most EAP methods in common 520 use are not compliant. Additionally, such requirements assume that 521 EAP packets are visible to a passive attacker. As EAP is used in 522 protected tunnels such as in L2TP, in IKEv2 and here, this assumption 523 may not be required. If we consider the server authenticated by its 524 certificate, it may be acceptable to use a non-MA method. 526 It has been suggested that identity protection is not important 527 enough to add a roundtrip, and so we should have the client send the 528 username in the ClientHello. We are not sure about how others feel 529 about this, and would like to solicit the reviewers opinion. Note 530 that if this is done, the client sends the user name before ever 531 receiving any indication that the server actually supports TEE. This 532 might be acceptable in an email client, where the server is 533 preconfigured, but it may be unacceptable in other uses, such as web 534 browsers. 536 11. References 538 11.1. Normative References 540 [EAP] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. 541 Levkowetz, "Extensible Authentication Protocol (EAP)", 542 RFC 3748, June 2004. 544 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 545 Requirement Levels", BCP 14, RFC 2119, March 1997. 547 [TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security 548 (TLS) Protocol Version 1.1", RFC 4346, April 2006. 550 [TLS-EXT] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., 551 and T. Wright, "Transport Layer Security (TLS) 552 Extensions", RFC 4366, April 2006. 554 11.2. Informative References 556 [Compound-Authentication] 557 Puthenkulam, J., Lortz, V., Palekar, A., and D. Simon, 558 "The Compound Authentication Binding Problem", 559 draft-puthenkulam-eap-binding-04 (work in progress), 560 October 2003. 562 [Dia-EAP] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible 563 Authentication Protocol (EAP) Application", RFC 4072, 564 August 2005. 566 [Diameter] 567 Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. 568 Arkko, "Diameter Base Protocol", RFC 3588, September 2003. 570 [EAP-GPSK] 571 Clancy, T. and H. Tschofenig, "EAP Generalized Pre-Shared 572 Key (EAP-GPSK)", draft-ietf-emu-eap-gpsk-05 (work in 573 progress), April 2007. 575 [I-D.ietf-eap-keying] 576 Aboba, B., "Extensible Authentication Protocol (EAP) Key 577 Management Framework", draft-ietf-eap-keying-18 (work in 578 progress), February 2007. 580 [I.D.Webauth-phishing] 581 Hartman, S., "Requirements for Web Authentication 582 Resistant to Phishing", draft-hartman-webauth-phishing-03 583 (work in progress), March 2007. 585 [MITM] Asokan, N., Niemi, V., and K. Nyberg, "Man-in-the-Middle 586 in Tunneled Authentication Protocols", IACR ePrint 587 Archive , October 2002. 589 [RAD-EAP] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication 590 Dial In User Service) Support For Extensible 591 Authentication Protocol (EAP)", RFC 3579, September 2003. 593 [RADIUS] Rigney, C., Willens, S., Rubens, A., and W. Simpson, 594 "Remote Authentication Dial In User Service (RADIUS)", 595 RFC 2865, June 2000. 597 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 598 RFC 4306, December 2005. 600 [TLS-PSK] Eronen, P. and H. Tschofenig, "Pre-Shared Key Ciphersuites 601 for Transport Layer Security (TLS)", RFC 4279, 602 December 2005. 604 [TLS/IA] Funk, P., Blake-Wilson, S., Smith, H., Tschofenig, N., and 605 T. Hardjono, "TLS Inner Application Extension (TLS/IA)", 606 draft-funk-tls-inner-application-extension-03 (work in 607 progress), June 2006. 609 Authors' Addresses 611 Yoav Nir 612 Check Point Software Technologies Ltd. 613 5 Hasolelim st. 614 Tel Aviv 67897 615 Israel 617 Email: ynir@checkpoint.com 619 Yaron Sheffer 620 Check Point Software Technologies Ltd. 621 5 Hasolelim st. 622 Tel Aviv 67897 623 Israel 625 Email: yaronf at checkpoint dot com 627 Hannes Tschofenig 628 Nokia Siemens Networks 629 Otto-Hahn-Ring 6 630 Munich, Bavaria 81739 631 Germany 633 Email: Hannes.Tschofenig@siemens.com 634 URI: http://www.tschofenig.com 636 Peter Gutmann 637 University of Auckland 638 Department of Computer Science 639 New Zealand 641 Email: pgut001@cs.auckland.ac.nz 643 Full Copyright Statement 645 Copyright (C) The IETF Trust (2007). 647 This document is subject to the rights, licenses and restrictions 648 contained in BCP 78, and except as set forth therein, the authors 649 retain all their rights. 651 This document and the information contained herein are provided on an 652 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 653 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 654 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 655 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 656 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 657 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 659 Intellectual Property 661 The IETF takes no position regarding the validity or scope of any 662 Intellectual Property Rights or other rights that might be claimed to 663 pertain to the implementation or use of the technology described in 664 this document or the extent to which any license under such rights 665 might or might not be available; nor does it represent that it has 666 made any independent effort to identify any such rights. 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