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Williams 3 Internet-Draft Sun 4 Intended status: Standards Track March 25, 2009 5 Expires: September 26, 2009 7 Extended Generic Security Service Mechanism Inquiry APIs 8 draft-ietf-kitten-extended-mech-inquiry-05.txt 10 Status of this Memo 12 This Internet-Draft is submitted to IETF in full conformance with the 13 provisions of BCP 78 and BCP 79. 15 Internet-Drafts are working documents of the Internet Engineering 16 Task Force (IETF), its areas, and its working groups. Note that 17 other groups may also distribute working documents as Internet- 18 Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six months 21 and may be updated, replaced, or obsoleted by other documents at any 22 time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt. 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 This Internet-Draft will expire on September 26, 2009. 33 Copyright Notice 35 Copyright (c) 2009 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents in effect on the date of 40 publication of this document (http://trustee.ietf.org/license-info). 41 Please review these documents carefully, as they describe your rights 42 and restrictions with respect to this document. 44 Abstract 46 This document introduces new application programming interfaces 47 (APIs) to the Generic Security Services API (GSS-API) for extended 48 mechanism attribute inquiry. These interfaces are primarily intended 49 to reduce instances of hardcoding of mechanism identifiers in GSS 50 applications. 52 These interfaces include: mechanism attributes and attribute sets, a 53 function for inquiring the attributes of a mechanism, a function for 54 indicating mechanisms that posses given attributes, and a function 55 for displaying mechanism attributes. 57 Table of Contents 59 1. Conventions used in this document . . . . . . . . . . . . 3 60 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 61 3. New GSS-API Interfaces . . . . . . . . . . . . . . . . . . 3 62 3.1. Mechanism Attributes and Attribute Sets . . . . . . . . . 3 63 3.2. List of Known Mechanism Attributes . . . . . . . . . . . . 4 64 3.3. Mechanism Attribute Sets of Existing Mechs . . . . . . . . 6 65 3.4. New GSS-API Function Interfaces . . . . . . . . . . . . . 7 66 3.4.1. Mechanism Attribute Criticality . . . . . . . . . . . . . 8 67 3.4.2. GSS_Indicate_mechs_by_attr() . . . . . . . . . . . . . . . 8 68 3.4.3. GSS_Inquire_attrs_for_mech() . . . . . . . . . . . . . . . 9 69 3.4.4. GSS_Display_mech_attr() . . . . . . . . . . . . . . . . . 9 70 3.4.5. New Major Status Values . . . . . . . . . . . . . . . . . 10 71 3.4.6. C-Bindings . . . . . . . . . . . . . . . . . . . . . . . . 10 72 4. Requirements for Mechanism Designers . . . . . . . . . . . 11 73 5. IANA Considerations . . . . . . . . . . . . . . . . . . . 11 74 6. Security considerations . . . . . . . . . . . . . . . . . 11 75 7. References . . . . . . . . . . . . . . . . . . . . . . . . 12 76 7.1. Normative References . . . . . . . . . . . . . . . . . . . 12 77 7.2. Informative References . . . . . . . . . . . . . . . . . . 12 78 Author's Address . . . . . . . . . . . . . . . . . . . . . 12 80 1. Conventions used in this document 82 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 83 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 84 document are to be interpreted as described in [RFC2119]. 86 2. Introduction 88 GSS-API [RFC2743] mechanisms have a number of properties that may be 89 of interest to applications. The lack of APIs for inquiring about 90 available mechanisms' properties has meant that many GSS-API 91 applications must hardcode mechanism OIDs. Ongoing work may result 92 in a variety of new GSS-API mechanisms. Applications should not have 93 to hardcode their OIDs. 95 For example, the SSHv2 protocol [RFC4251] supports the use of GSS-API 96 mechanisms for authentication [RFC4462], but it explicitly prohibits 97 the use of SPNEGO [RFC4178]. Future mechanisms that negotiate 98 mechanisms would have to be forbidden as well, but there is no way to 99 implement applications that inquire what mechanisms are available and 100 then programmatically exclude mechanisms "like SPNEGO". 102 3. New GSS-API Interfaces 104 We introduce a new concept: that of mechanism attributes. By 105 allowing applications to query the set of attributes associated with 106 individual mechanisms and to find out which mechanisms support a 107 given set of attributes we allow applications to select mechanisms 108 based on their attributes yet without having to hardcode mechanism 109 OIDs. 111 Section 3.1 describes the mechanism attributes concept. Sections 112 3.4.2, 3.4.3 and 3.4.4 describe three new interfaces that deal in 113 mechanisms and attribute sets: 115 o GSS_Indicate_mechs_by_attrs() 116 o GSS_Inquire_attrs_for_mech() 117 o GSS_Display_mech_attr() 119 3.1. Mechanism Attributes and Attribute Sets 121 An abstraction for the features provided by mechanisms and pseudo- 122 mechanisms is needed in order to facilitate the programmatic 123 selection of mechanisms. Pseudo-mechanisms are mechanisms which make 124 reference to other mechanisms in order to provide their services. 125 For example, SPNEGO is a pseudo-mechanism, for without other 126 mechanisms SPNEGO is useless. 128 Two data types are needed: one for individual mechanism attributes 129 and one for mechanism attribute sets. To simplify the mechanism 130 attributes interfaces we reuse the 'OID' and 'OID set' data types and 131 model individual mechanism attribute types as OIDs. 133 To this end we define an open namespace of mechanism attributes and 134 assign them arcs off of this OID: 136 [1.3.6.1.5.5.13 appears to be available; see 137 http://www.iana.org/assignments/smi-numbers] 139 Each mechanism has a set of mechanism attributes that it supports as 140 described in its specification. 142 3.2. List of Known Mechanism Attributes 144 +-------------------------+---------+-------------------------+ 145 | Mech Attr Name | OID Arc | Arc Name | 146 +-------------------------+---------+-------------------------+ 147 | GSS_C_MA_MECH_CONCRETE | (1) | concrete-mech | 148 | GSS_C_MA_MECH_PSEUDO | (2) | pseudo-mech | 149 | GSS_C_MA_MECH_COMPOSITE | (3) | composite-mech | 150 | GSS_C_MA_MECH_NEGO | (4) | mech-negotiation-mech | 151 | GSS_C_MA_MECH_GLUE | (5) | mech-glue | 152 | GSS_C_MA_NOT_MECH | (6) | not-mech | 153 | GSS_C_MA_DEPRECATED | (7) | mech-deprecated | 154 | GSS_C_MA_NOT_DFLT_MECH | (8) | mech-not-default | 155 | GSS_C_MA_ITOK_FRAMED | (9) | initial-is-framed | 156 | GSS_C_MA_AUTH_INIT | (10) | auth-init-princ | 157 | GSS_C_MA_AUTH_TARG | (11) | auth-targ-princ | 158 | GSS_C_MA_AUTH_INIT_INIT | (12) | auth-init-princ-initial | 159 | GSS_C_MA_AUTH_TARG_INIT | (13) | auth-targ-princ-initial | 160 | GSS_C_MA_AUTH_INIT_ANON | (14) | auth-init-princ-anon | 161 | GSS_C_MA_AUTH_TARG_ANON | (15) | auth-targ-princ-anon | 162 | GSS_C_MA_DELEG_CRED | (16) | deleg-cred | 163 | GSS_C_MA_INTEG_PROT | (17) | integ-prot | 164 | GSS_C_MA_CONF_PROT | (18) | conf-prot | 165 | GSS_C_MA_MIC | (19) | mic | 166 | GSS_C_MA_WRAP | (20) | wrap | 167 | GSS_C_MA_PROT_READY | (21) | prot-ready | 168 | GSS_C_MA_REPLAY_DET | (22) | replay-detection | 169 | GSS_C_MA_OOS_DET | (23) | oos-detection | 170 | GSS_C_MA_CBINDINGS | (24) | channel-bindings | 171 | GSS_C_MA_PFS | (25) | pfs | 172 | GSS_C_MA_COMPRESS | (26) | compress | 173 | GSS_C_MA_CTX_TRANS | (27) | context-transfer | 174 | | (28..) | | 175 +-------------------------+---------+-------------------------+ 177 Table 1 179 +-------------------------+-----------------------------------------+ 180 | Mech Attr Name | Purpose | 181 +-------------------------+-----------------------------------------+ 182 | GSS_C_MA_MECH_CONCRETE | Indicates that a mech is neither a | 183 | | pseudo- mechanism nor a composite | 184 | | mechanism. | 185 | GSS_C_MA_MECH_PSEUDO | Indicates that a mech is a | 186 | | pseudo-mechanism. | 187 | GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite of | 188 | | other mechanisms. This is reserved for | 189 | | a specification of "stackable" | 190 | | pseudo-mechanisms. | 191 | GSS_C_MA_MECH_NEGO | Indicates that a mech negotiates other | 192 | | mechs (e.g., SPNEGO has this | 193 | | attribute). | 194 | GSS_C_MA_MECH_GLUE | Indicates that the OID is not for a | 195 | | mechanism but for the GSS-API itself. | 196 | GSS_C_MA_NOT_MECH | Indicates that the OID is known, yet | 197 | | also known not to be the OID of any | 198 | | GSS-API mechanism (or the GSS-API | 199 | | itself). | 200 | GSS_C_MA_DEPRECATED | Indicates that a mech (or its OID) is | 201 | | deprecated and MUST NOT be used as a | 202 | | default mechanism. | 203 | GSS_C_MA_NOT_DFLT_MECH | Indicates that a mech (or its OID) MUST | 204 | | NOT be used as a default mechanism. | 205 | GSS_C_MA_ITOK_FRAMED | Indicates that the given mechanism's | 206 | | initial context tokens are properly | 207 | | framed as per-section 3.1 of rfc2743. | 208 | GSS_C_MA_AUTH_INIT | Indicates support for authentication of | 209 | | initiator to acceptor. | 210 | GSS_C_MA_AUTH_TARG | Indicates support for authentication of | 211 | | acceptor to initiator. | 212 | GSS_C_MA_AUTH_INIT_INIT | Indicates support for "initial" | 213 | | authentication of initiator to | 214 | | acceptor. "Initial authentication" | 215 | | refers to the use of passwords, or keys | 216 | | stored on tokens, for authentication. | 217 | | Whether a mechanism supports initial | 218 | | authentication may depend on IETF | 219 | | consensus (see Security | 220 | | Considerations). | 221 | GSS_C_MA_AUTH_TARG_INIT | Indicates support for initial | 222 | | authentication of acceptor to | 223 | | initiator. | 224 | GSS_C_MA_AUTH_INIT_ANON | Indicates support for | 225 | | GSS_C_NT_ANONYMOUS as an initiator | 226 | | principal name. | 227 | GSS_C_MA_AUTH_TARG_ANON | Indicates support for | 228 | | GSS_C_NT_ANONYMOUS as a target | 229 | | principal name. | 230 | GSS_C_MA_DELEG_CRED | Indicates support for credential | 231 | | delegation. | 232 | GSS_C_MA_INTEG_PROT | Indicates support for per-message | 233 | | integrity protection. | 234 | GSS_C_MA_CONF_PROT | Indicates support for per-message | 235 | | confidentiality protection. | 236 | GSS_C_MA_MIC | Indicates support for MIC tokens. | 237 | GSS_C_MA_WRAP | Indicates support for WRAP tokens. | 238 | GSS_C_MA_PROT_READY | Indicates support for per-message | 239 | | protection prior to full context | 240 | | establishment. | 241 | GSS_C_MA_REPLAY_DET | Indicates support for replay detection. | 242 | GSS_C_MA_OOS_DET | Indicates support for out-of-sequence | 243 | | detection. | 244 | GSS_C_MA_CBINDINGS | Indicates support for channel bindings. | 245 | GSS_C_MA_PFS | Indicates support for Perfect Forward | 246 | | Security. | 247 | GSS_C_MA_COMPRESS | Indicates support for compression of | 248 | | data inputs to GSS_Wrap(). | 249 | GSS_C_MA_CTX_TRANS | Indicates support for security context | 250 | | export/import. | 251 +-------------------------+-----------------------------------------+ 253 Table 2 255 3.3. Mechanism Attribute Sets of Existing Mechs 257 The Kerberos V mechanism [RFC1964] provides the following mechanism 258 attributes: 260 o GSS_C_MA_MECH_CONCRETE 261 o GSS_C_MA_ITOK_FRAMED 262 o GSS_C_MA_AUTH_INIT 263 o GSS_C_MA_AUTH_TARG 264 o GSS_C_MA_DELEG_CRED 265 o GSS_C_MA_INTEG_PROT 266 o GSS_C_MA_CONF_PROT 267 o GSS_C_MA_MIC 268 o GSS_C_MA_WRAP 269 o GSS_C_MA_PROT_READY 270 o GSS_C_MA_REPLAY_DET 271 o GSS_C_MA_OOS_DET 272 o GSS_C_MA_CBINDINGS 273 o GSS_C_MA_CTX_TRANS (some implementations, using implementation- 274 specific exported context token formats) 276 The Kerberos V mechanism also has a deprecated OID which has the same 277 mechanism attributes as above, and GSS_C_MA_DEPRECATED. 279 The mechanism attributes of the SPKM [RFC2025] family of mechanisms 280 will be provided in a separate document as SPKM is current being 281 reviewed for possibly significant changes due to problems in its 282 specifications. 284 The LIPKEY mechanism [RFC2847] offers the following attributes: 286 o GSS_C_MA_MECH_CONCRETE 287 o GSS_C_MA_ITOK_FRAMED 288 o GSS_C_MA_AUTH_INIT_INIT 289 o GSS_C_MA_AUTH_TARG (from SPKM-3) 290 o GSS_C_MA_AUTH_TARG_ANON (from SPKM-3) 291 o GSS_C_MA_INTEG_PROT 292 o GSS_C_MA_CONF_PROT 293 o GSS_C_MA_REPLAY_DET 294 o GSS_C_MA_OOS_DET 295 o GSS_C_MA_CTX_TRANS (some implementations, using implementation- 296 specific exported context token formats) 298 (LIPKEY should also provide GSS_C_MA_CBINDINGS, but SPKM-3 299 requires clarifications on this point.) 301 The SPNEGO mechanism [RFC4178] provides the following attributes: 302 o GSS_C_MA_MECH_NEGO 303 o GSS_C_MA_ITOK_FRAMED 305 All other mechanisms' attributes will be described elsewhere. 307 3.4. New GSS-API Function Interfaces 309 Several new interfaces are given by which, for example, GSS-API 310 applications may determine what features are provided by a given 311 mechanism and what mechanisms provide what features. 313 These new interfaces are all OPTIONAL. 315 Applications should use GSS_Indicate_mechs_by_attr() instead of 316 GSS_Indicate_mechs() wherever possible. 318 Applications can use GSS_Indicate_mechs_by_attr() to determine what, 319 if any, mechanisms provide a given set of features. 321 GSS_Indicate_mechs_by_attr() can also be used to indicate (as in 322 GSS_Indicate_mechs()) the set of available mechanisms of each type 323 (concrete, mechanism negotiation pseudo-mechanism, etc.). 325 3.4.1. Mechanism Attribute Criticality 327 Mechanism attributes may be added at any time. Not only may 328 attributes be added to the list of known mechanism attributes at any 329 time, but the set of mechanism attributes supported by a mechanism 330 can be changed at any time. 332 For example, new attributes might be added to reflect whether a 333 mechanism's initiator must contact online infrastructure, and/or 334 whether the acceptor must do so. In this example the Kerberos V 335 mechanism would gain a new attribute even though the mechanism itself 336 is not modified. 338 Applications making use of attributes not defined herein then would 339 have no way of knowing whether a GSS-API implementation and its 340 mechanisms know about new mechanism attributes. To address this 341 problem GSS_Indicate_mechs_by_attr() and GSS_Indicate_mechs_by_attr() 342 support a notion of critical mechanism attributes. Applications can 343 search for mechanisms that understand mechanism attributes that are 344 critical to the application, and the application may ask what 345 mechanism attributes are understood by a given mechanism. 347 3.4.2. GSS_Indicate_mechs_by_attr() 349 Inputs: 350 o desired_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* 351 OIDs that the mechanisms indicated in the mechs output parameter 352 MUST offer 353 o except_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* 354 OIDs that the mechanisms indicated in the mechs output parameter 355 MUST NOT offer 356 o critical_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* 357 OIDs that the mechanisms indicated in the mechs output parameter 358 MUST understand (i.e., mechs must know whether critical attributes 359 are or are not supported) 361 Outputs: 362 o major_status INTEGER 363 o minor_status INTEGER 364 o mechs SET OF OBJECT IDENTIFIER -- set of mechanisms that support 365 the given desired_mech_attrs but not the except_mech_attrs, and 366 all of which understand the given critical_mech_attrs (the caller 367 must release this output with GSS_Release_oid_set()) 369 Return major_status codes: 370 o GSS_S_COMPLETE indicates success; the output mechs parameter MAY 371 be the empty set (GSS_C_NO_OID_SET). 372 o GSS_S_FAILURE indicates that the request failed for some other 373 reason. 375 GSS_Indicate_mechs_by_attrs() returns the set of OIDs corresponding 376 to mechanisms that offer at least the desired_mech_attrs but none of 377 the except_mech_attrs, and which understand all of the attributes 378 listed in critical_mech_attrs. 380 When all three set of OID input parameters are the empty set this 381 function acts as a version of GSS_indicate_mechs() that outputs the 382 set of all supported mechanisms. 384 3.4.3. GSS_Inquire_attrs_for_mech() 386 Inputs: 387 o mech OBJECT IDENTIFIER -- mechanism OID 389 Outputs: 390 o major_status INTEGER 391 o minor_status INTEGER 392 o mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs OIDs 393 (GSS_C_MA_*) supported by the mechanism (the caller must release 394 this output with GSS_Release_oid_set()) 395 o known_mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs 396 OIDs known to the mechanism implementation (the caller must 397 release this output with GSS_Release_oid_set()). 399 Return major_status codes: 400 o GSS_S_COMPLETE indicates success; the output mech_attrs parameter 401 MAY be the empty set (GSS_C_NO_OID_SET). 402 o GSS_S_BAD_MECH indicates that the mechanism named by the mech 403 parameter does not exist or that mech is GSS_C_NO_OID and no 404 default mechanism could be determined. 405 o GSS_S_FAILURE indicates that the request failed for some other 406 reason. 408 GSS_Inquire_mech_attrs_for_mech() indicates the set of mechanism 409 attributes supported by a given mechanism. 411 3.4.4. GSS_Display_mech_attr() 413 Inputs: 415 o mech_attr OBJECT IDENTIFIER -- mechanism attribute OID 417 Outputs: 418 o major_status INTEGER 419 o minor_status INTEGER 420 o name OCTET STRING, -- name of mechanism attribute (e.g., 421 GSS_C_MA_*) 422 o short_desc OCTET STRING, -- a short description of the mechanism 423 attribute (the caller must release this output with 424 GSS_Release_buffer()) 425 o long_desc OCTET STRING -- a longer description of the mechanism 426 attribute (the caller must release this output with 427 GSS_Release_buffer()) 429 Return major_status codes: 430 o GSS_S_COMPLETE indicates success. 431 o GSS_S_BAD_MECH_ATTR indicates that the mechanism attribute 432 referenced by the mech_attr parameter is unknown to the 433 implementation. 434 o GSS_S_FAILURE indicates that the request failed for some other 435 reason. 437 This function can be used to obtain human-readable descriptions of 438 GSS-API mechanism attributes. 440 3.4.5. New Major Status Values 442 A single new major status code is added for GSS_Display_mech_attr(): 443 o GSS_S_BAD_MECH_ATTR 444 roughly corresponding to GSS_S_BAD_MECH, but applicable to mechanism 445 attribute OIDs, rather than to mechanism OIDs. 447 For the C-bindings of the GSS-API [RFC2744] GSS_S_BAD_MECH_ATTR shall 448 have a routine error number of 19 (this is shifted to the left by 449 GSS_C_ROUTINE_ERROR_OFFSET). 451 3.4.6. C-Bindings 453 #define GSS_S_BAD_MECH_ATTR (19ul << GSS_C_ROUTINE_ERROR_OFFSET) 455 OM_uint32 gss_inquire_mechs_for_attrs( 456 OM_uint32 *minor_status, 457 const gss_OID_set desired_mech_attrs, 458 const gss_OID_set except_mech_attrs, 459 const gss_OID_set critical_mech_attrs, 460 gss_OID_set *mechs); 462 OM_uint32 gss_inquire_attrs_for_mech( 463 OM_uint32 *minor_status, 464 const gss_OID mech, 465 gss_OID_set *mech_attrs, 466 gss_OID_set *known_mech_attrs); 468 OM_uint32 gss_display_mech_attr( 469 OM_uint32 *minor_status, 470 const gss_OID mech_attr, 471 gss_buffer_t name, 472 gss_buffer_t short_desc, 473 gss_buffer_t long_desc); 475 Figure 1 477 Note that output buffers must be released via gss_release_buffer(). 478 Output OID sets must be released via gss_release_oid_set(). 480 4. Requirements for Mechanism Designers 482 All future GSS-API mechanism specifications MUST: 483 o list the set of GSS-API mechanism attributes associated with them 485 5. IANA Considerations 487 The namsepace of programming language symbols with names beginning 488 with GSS_C_MA_* is reserved for allocation by IESG Protocol Action. 489 The IANA should allocate a base OID, as an arc of 1.3.6.1.5.5, for 490 the set of GSS_C_MA_* described herein, and it should register all of 491 the GSS_C_MA_* values described in Section 3.2 493 6. Security considerations 495 This document specifies extensions to a security-related API. It 496 imposes new requirements on future GSS-API mechanisms, and the 497 specification of future protocols that use the GSS-API should make 498 reference to this document where applicable. The ability to inquire 499 about specific properties of mechanisms should improve security. 501 The semantics of each mechanism attribute may include a security 502 component. 504 Application developers must understand that mechanism attributes may 505 be added at any time, both, to the set of known mechanism attributes, 506 as well as to existing mechanism's sets of supported mechanism 507 attributes. Therefore application developers using the APIs 508 described herein must understand what mechanism attributes their 509 applications depend critically on, and must use the mechanism 510 attribute criticality features of these APIs. 512 7. References 514 7.1. Normative References 516 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 517 Requirement Levels", BCP 14, RFC 2119, March 1997. 519 [RFC2743] Linn, J., "Generic Security Service Application Program 520 Interface Version 2, Update 1", RFC 2743, January 2000. 522 [RFC2744] Wray, J., "Generic Security Service API Version 2 : 523 C-bindings", RFC 2744, January 2000. 525 7.2. Informative References 527 [RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", 528 RFC 1964, June 1996. 530 [RFC2025] Adams, C., "The Simple Public-Key GSS-API Mechanism 531 (SPKM)", RFC 2025, October 1996. 533 [RFC2847] Eisler, M., "LIPKEY - A Low Infrastructure Public Key 534 Mechanism Using SPKM", RFC 2847, June 2000. 536 [RFC4178] Zhu, L., Leach, P., Jaganathan, K., and W. Ingersoll, "The 537 Simple and Protected Generic Security Service Application 538 Program Interface (GSS-API) Negotiation Mechanism", 539 RFC 4178, October 2005. 541 [RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) 542 Protocol Architecture", RFC 4251, January 2006. 544 [RFC4462] Hutzelman, J., Salowey, J., Galbraith, J., and V. Welch, 545 "Generic Security Service Application Program Interface 546 (GSS-API) Authentication and Key Exchange for the Secure 547 Shell (SSH) Protocol", RFC 4462, May 2006. 549 Author's Address 551 Nicolas Williams 552 Sun Microsystems 553 5300 Riata Trace Ct 554 Austin, TX 78727 555 US 557 Email: Nicolas.Williams@sun.com