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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M. Blanchet 3 Internet-Draft Viagenie 4 Intended status: Informational A. Sullivan 5 Expires: June 12, 2011 December 9, 2010 7 Stringprep Revision Problem Statement 8 draft-ietf-precis-problem-statement-01.txt 10 Abstract 12 Using Unicode codepoints in protocol strings that expect comparison 13 with other strings requires preparation of the string that contains 14 the Unicode codepoints. Internationalizing Domain Names in 15 Applications (IDNA2003) defined and used Stringprep and Nameprep. 16 Other protocols subsequently defined Stringprep profiles. A new 17 approach different from Stringprep and Nameprep is used for a 18 revision of IDNA2003 (called IDNA2008). Other Stringprep profiles 19 need to be similarly updated or a replacement of Stringprep needs to 20 be designed. This document outlines the issues to be faced by those 21 designing a Stringprep replacement. 23 Status of this Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on June 12, 2011. 40 Copyright Notice 42 Copyright (c) 2010 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 This document may contain material from IETF Documents or IETF 56 Contributions published or made publicly available before November 57 10, 2008. The person(s) controlling the copyright in some of this 58 material may not have granted the IETF Trust the right to allow 59 modifications of such material outside the IETF Standards Process. 60 Without obtaining an adequate license from the person(s) controlling 61 the copyright in such materials, this document may not be modified 62 outside the IETF Standards Process, and derivative works of it may 63 not be created outside the IETF Standards Process, except to format 64 it for publication as an RFC or to translate it into languages other 65 than English. 67 Table of Contents 69 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 70 2. Issues raised during newprep BOF . . . . . . . . . . . . . . . 5 71 3. Major Topics for Consideration . . . . . . . . . . . . . . . . 6 72 3.1. Comparison . . . . . . . . . . . . . . . . . . . . . . . . 6 73 3.1.1. Comparison methods . . . . . . . . . . . . . . . . . . 6 74 3.1.2. Effect of comparison . . . . . . . . . . . . . . . . . 7 75 3.2. Dealing with characters . . . . . . . . . . . . . . . . . 7 76 3.2.1. Case folding, case sensitivity, and case 77 preservation . . . . . . . . . . . . . . . . . . . . . 7 78 3.2.2. Stringprep and NFKC . . . . . . . . . . . . . . . . . 7 79 3.2.3. Character mapping . . . . . . . . . . . . . . . . . . 8 80 3.2.4. Prohibited characters . . . . . . . . . . . . . . . . 8 81 3.2.5. Internal structure, delimiters, and special 82 characters . . . . . . . . . . . . . . . . . . . . . . 8 83 3.3. Where the data comes from and where it goes . . . . . . . 9 84 3.3.1. User input and the source of protocol elements . . . . 9 85 3.3.2. User output . . . . . . . . . . . . . . . . . . . . . 9 86 3.3.3. Operations . . . . . . . . . . . . . . . . . . . . . . 10 87 4. Considerations for Stringprep replacement . . . . . . . . . . 10 88 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 89 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 90 7. Discussion home for this draft . . . . . . . . . . . . . . . . 11 91 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 92 9. Informative References . . . . . . . . . . . . . . . . . . . . 11 93 Appendix A. Protocols known to be using Stringprep . . . . . . . 15 94 Appendix B. Changes between versions . . . . . . . . . . . . . . 15 95 B.1. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 96 B.2. 01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 97 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 99 1. Introduction 101 Internationalizing Domain Names in Applications (IDNA2003) [RFC3490], 102 [RFC3491], [RFC3492], [RFC3454] described a mechanism for encoding 103 Unicode labels making up Internationalized Domain Names (IDNs) as 104 standard DNS labels. The labels were processed using a method called 105 Nameprep [RFC3491] and Punycode [RFC3492]. That method was specific 106 to IDNA2003, but is generalized as Stringprep [RFC3454]. The general 107 mechanism can be used to help other protocols with similar needs, but 108 with different constraints than IDNA2003. 110 Stringprep defines a framework within which protocols define their 111 Stringprep profiles. Known IETF specifications using Stringprep are 112 listed below: 113 o The Nameprep profile [RFC3490] for use in Internationalized Domain 114 Names (IDNs); 115 o NFSv4 [RFC3530] and NFSv4.1 [RFC5661]; 116 o The iSCSI profile [RFC3722] for use in Internet Small Computer 117 Systems Interface (iSCSI) Names; 118 o EAP [RFC3748]; 119 o The Nodeprep and Resourceprep profiles [RFC3920] for use in the 120 Extensible Messaging and Presence Protocol (XMPP), and the XMPP to 121 CPIM mapping [RFC3922]; 122 o The Policy MIB profile [RFC4011] for use in the Simple Network 123 Management Protocol (SNMP); 124 o The SASLprep profile [RFC4013] for use in the Simple 125 Authentication and Security Layer (SASL), and SASL itself 126 [RFC4422]; 127 o TLS [RFC4279]; 128 o IMAP4 using SASLprep [RFC4314]; 129 o The trace profile [RFC4505] for use with the SASL ANONYMOUS 130 mechanism; 131 o The LDAP profile [RFC4518] for use with LDAP [RFC4511] and its 132 authentication methods [RFC4513]; 133 o Plain SASL using SASLprep [RFC4616]; 134 o NNTP using SASLprep [RFC4643]; 135 o PKIX subject identification using LDAPprep [RFC4683]; 136 o Internet Application Protocol Collation Registry [RFC4790]; 137 o SMTP Auth using SASLprep [RFC4954]; 138 o POP3 Auth using SASLprep [RFC5034]; 139 o TLS SRP using SASLprep [RFC5054]; 140 o IRI and URI in XMPP [RFC5122]; 141 o PKIX CRL using LDAPprep [RFC5280]; 142 o IAX using Nameprep [RFC5456]; 143 o SASL SCRAM using SASLprep [RFC5802]; 144 o Remote management of Sieve using SASLprep [RFC5804]; 145 o The i;unicode-casemap Unicode Collation [RFC5051]. 147 There turned out to be some difficulties with IDNA2003, documented in 148 [RFC4690]. These difficulties led to a new IDN specification, called 149 IDNA2008 [RFC5890], [RFC5891], [RFC5892], [RFC5893]. Additional 150 background and explanations of the decisions embodied in IDNA2008 is 151 presented in [RFC5894]. One of the effects of IDNA2008 is that 152 Nameprep and Stringprep are not used at all. Instead, an algorithm 153 based on Unicode properties of codepoints is defined. That algorithm 154 generates a stable and complete table of the supported Unicode 155 codepoints. This algorithm is based on an inclusion-based approach, 156 instead of the exclusion-based approach of Stringprep/Nameprep. 158 This document lists the shortcomings and issues found by protocols 159 listed above that defined Stringprep profiles. It also lists some 160 early conclusions and requirements for a potential replacement of 161 Stringprep. 163 2. Issues raised during newprep BOF 165 During IETF 77, a BOF discussed the current state of the protocols 166 that have defined Stringprep profiles [NEWPREP]. The main 167 conclusions are: 168 o Stringprep is bound to a specific version of Unicode: 3.2. 169 Stringprep has not been updated to new versions of Unicode. 170 Therefore, the protocols using Stringprep are stuck to Unicode 171 3.2. 172 o The protocols need to be updated to support new versions of 173 Unicode. The protocols would like to not be bound to a specific 174 version of Unicode, but rather have better Unicode agility in the 175 way of IDNA2008. This is important partly because it is usually 176 impossible for an application to require Unicode 3.2; the 177 application gets whatever version of Unicode is available on the 178 host. 179 o The protocols require better bidirectional support (bidi) than 180 currently offered by Stringprep. 181 o If the protocols are updated to use a new version of Stringprep or 182 another framework, then backward compatibility is an important 183 requirement. For example, Stringprep is based on and may use NFKC 184 [UAX15], while IDNA2008 mostly uses NFC [UAX15]. 185 o Protocols use each other; for example, a protocol can use user 186 identifiers that are later passed to SASL, LDAP or another 187 authentication mechanism. Therefore, common set of rules or 188 classes of strings are preferred over specific rules for each 189 protocol. 191 Protocols that use Stringprep profiles use strings for different 192 purposes: 193 o XMPP uses a different Stringprep profile for each part of the XMPP 194 address (JID): a localpart which is similar to a username and used 195 for authentication, a domainpart which is a domain name and a 196 resource part which is less restrictive than the localpart. 197 o iSCSI uses a Stringprep profile for the IQN, which is very similar 198 to (often is) a DNS domain name. 199 o SASL and LDAP uses a Stringprep profile for usernames. 200 o LDAP uses a set of Stringprep profiles. 202 During the newprep BOF, it was the consensus of the attendees that it 203 would be highly desirable to have a replacement of Stringprep, with 204 similar characteristics to IDNA2008. That replacement should be 205 defined so that the protocols could use internationalized strings 206 without a lot of specialized internationalization work, since 207 internationalization expertise is not available in the respective 208 protocols or working groups. 210 3. Major Topics for Consideration 212 This section provides an overview of major topics that a Stringprep 213 replacement needs to address. The headings correspond roughly with 214 categories under which known Stringprep-using protocol RFCs have been 215 evaluated. For the details of those evaluations, see Appendix A. 217 3.1. Comparison 219 3.1.1. Comparison methods 221 Identifiers can be conveniently organized into three classes or 222 "buckets": 224 1. Identifiers that must compare equally byte for byte. [[anchor4: 225 In the Jabber discussion from Beijing, Ted Hardie asked that (1) 226 actually be "codepoint for codepoint". Is that what's intended? 227 It seems to me that that is already a case of (2), because 228 there's an algorithm to compare (say) my UTF-16 and your UCS-4. 229 Discussion would be helpful, please. --ajs@crankycanuck.ca]] 230 2. Identifiers that do not compare equally byte for byte, but that 231 can always be compared for equality based on an algorithm 232 everyone can agree on. 233 3. Identifiers for which there is no single comparison algorithm on 234 which everyone can agree. (For instance, there may be locale- 235 sensitive comparison rules for identifiers.) 237 A subclass of case (3) is one in which, within some constrained 238 population, the comparison rules are clear even though such rules are 239 not universally applicable. So, for instance, users of US-ASCII may 240 all agree on a comparison function, but the set of US-ASCII users and 241 Turkish users may not all agree about the same comparison function. 242 For the purposes of the precis work, it is not plain whether this 243 subclass case is relevant, so categorization will include it. 245 In the section treating the existing known cases, Appendix A, these 246 "buckets" will be called Type 1, Type 2, Type 3, and Type 3a. 248 3.1.2. Effect of comparison 250 The comparisons outlined in Section 3.1.1 may have different effects 251 when applied. It is necessary to evaluate the effects if a 252 comparison results in a false positive, and what the effects are if a 253 comparison results in a false negative. It is particularly important 254 to evaluate the effects on security of these answers. 256 3.2. Dealing with characters 258 3.2.1. Case folding, case sensitivity, and case preservation 260 In IDNA2003, labels are always mapped to lower case before the 261 Punycode transformation. In IDNA2003, there is no mapping at all: 262 input is either a valid U-label or it is not. At the same time, 263 upper-case characters are by definition not valid U-labels, because 264 they fall into the Unstable category (category B) of [RFC5892]. 266 If there are protocols that require upper and lower cases be 267 preserved, then the analogy with IDNA2008 will break down. 268 Accordingly, existing protocols are to be evaluated according to the 269 following criteria: 271 1. Does the protocol use case folding? For all blocks of code 272 points, or just for certain subsets? 273 2. Is the system or protocol case sensitive? 274 3. Does the system or protocol preserve case? 276 3.2.2. Stringprep and NFKC 278 Stringprep profiles may use normalization. If they do, they use NFKC 279 [UAX15]. It is not clear that NFKC is the right normalization to use 280 in all cases. In [UAX15], there is the following observation 281 regarding Normalization Forms KC and KD: "It is best to think of 282 these Normalization Forms as being like uppercase or lowercase 283 mappings: useful in certain contexts for identifying core meanings, 284 but also performing modifications to the text that may not always be 285 appropriate." For things like the spelling of users' names, then, 286 NFKC may not be the best form to use. At the same time, one of the 287 nice things about NFKC is that it deals with the width of characters 288 that are otherwise similar, by canonicalizing half-width to full- 289 width. This mapping step can be crucial in practice. The WG will 290 need to analyze the different use profiles and consider whether NFKC 291 or NFC is a better normalization for each profile. 293 For the purposes of evaluating an existing example of Stringprep use, 294 it is helpful to know whether it uses no normalization, NFKC, or NFC. 296 3.2.3. Character mapping 298 Along with the case mapping issues raised in Section 3.2.1, there is 299 the question of whether some characters are mapped either to other 300 characters or to nothing during Stringprep. [RFC3454], Section 3, 301 outlines a number of characters that are mapped to nothing, and also 302 permits Stringprep profiles to define their own mappings. 304 3.2.4. Prohibited characters 306 Along with case folding and other character mappings, many protocols 307 have characters that are simply disallowed. For example, control 308 characters and special characters such as "@" or "/" may be 309 prohibited in a protocol. 311 One of the primary changes of IDNA2008 is in the way it approaches 312 Unicode code points. IDNA2003 created an explicit list of excluded 313 or mapped-away characters; anything in Unicode 3.2 that was not so 314 listed could be assumed to be allowed under the protocol. IDNA2008 315 begins instead from the assumption that code points are disallowed, 316 and then relies on Unicode properties to derive whether a given code 317 point actually is allowed in the protocol. 319 Moreover, there is more than one class of "allowed in the protocol". 320 While some code points are disallowed outright, some are allowed only 321 in certain contexts. The reasons for the context-dependent rules 322 have to do with the way some characters are used. For instance, the 323 ZERO WIDTH JOINER and ZERO WIDTH NON-JOINER (ZWJ, U+200D and ZWNJ, 324 U+200C) are allowed with contextual rules because they are required 325 in some circumstances, yet are considered punctuation by Unicode and 326 would therefore be DISALLOWED under the usual IDNA2008 derivation 327 rules. 329 3.2.5. Internal structure, delimiters, and special characters 331 IDNA2008 has a special problem with delimiters, because the delimiter 332 "character" in the DNS wire format is not really part of the data. 333 In DNS, the wire format indicates label length. When the label is 334 presented in presentation format as part of a fully qualified domain 335 name, the label separator FULL STOP, U+002E (.) is used. But because 336 that label separator does not travel with the wire format of the 337 domain name, there is no way to encode a different, 338 "internationalized" separator in IDNA2008. 340 Other protocols may include characters with similar special meaning 341 within the protocol. Common characters for these purposes include 342 FULL STOP, U+002E (.); COMMERCIAL AT, U+0040 (@); HYPHEN-MINUS, 343 U+002D (-); SOLIDUS, U+002F (/); and LOW LINE, U+005F (_). The mere 344 inclusion of such a character in the protocol is not enough for it to 345 be considered similar to another protocol using the same character; 346 instead, handling of the character must be taken into consideration 347 as well. 349 An important issue to tackle here is whether it is valuable to map to 350 or from these special characters as part of the Stringprep 351 replacement. In some locales, the analogue to FULL STOP, U+002E is 352 some other character, and users may expect to be able to substitute 353 their normal stop for FULL STOP. 355 3.3. Where the data comes from and where it goes 357 3.3.1. User input and the source of protocol elements 359 Some protocol elements are provided by users, and others are not. 360 Those that are not may presumably be subject to greater restrictions, 361 whereas those that users provide likely need to permit the broadest 362 range of code points. The following questions are helpful: 364 1. Do users input the strings directly? 365 2. If so, how? (keyboard, stylus, voice, copy-paste, etc.) 366 3. Where do we place the dividing line between user interface and 367 protocol? (see [RFC5895]) 369 3.3.2. User output 371 Just as only some protocol elements are expected to be entered 372 directly by users, only some protocol elements are intended to be 373 consumed directly by users. It is important to know how users are 374 expected to be able to consume the protocol elements, because 375 different environments present different challenges. An element that 376 is only ever delivered as part of a vCard remains in machine-readable 377 format, so the problem of visual confusion is not a great one. Is 378 the protocol element published as part of a vCard, a web directory, 379 on a business card, or on "the side of a bus"? Do users use the 380 protocol element as an identifier (which means that they might enter 381 it again in some other context)? 383 3.3.3. Operations 385 Some strings are useful as part of the protocol but are not used as 386 input to other operations (for instance, purely informative or 387 descriptive text). Other strings are used directly as input to other 388 operations (such as cryptographic hash functions), or are used 389 together with other strings to (such as concatenating a string with 390 some others to form a unique identifier). 392 3.3.3.1. String classes 394 Strings often have a similar function in different protocols. For 395 instance, many different protocols contain user identifiers or 396 passwords. A single profile for all such uses might be desirable. 398 Often, a string in a protocol is effectively a protocol element from 399 another protocol. For instance, different systems might use the same 400 credentials database for authentication. 402 3.3.3.2. Community considerations 404 A Stringprep replacement that does anything more than just update 405 Stringprep to the latest version of Unicode will probably entail some 406 changes. It is important to identify the willingness of the 407 protocol-using community to accept backwards-incompatible changes. 408 By the same token, it is important to evaluate the desire of the 409 community for features not available under Stringprep. 411 4. Considerations for Stringprep replacement 413 The above suggests the following direction for the working group: 414 o A stringprep replacement should be defined. 415 o The replacement should take an approach similar to IDNA2008, in 416 that it enables Unicode agility. 417 o Protocols share similar characteristics of strings. Therefore, 418 defining i18n preparation algorithms for a (small) set of string 419 classes may be sufficient for most cases and provides the 420 coherence among a set of protocol friends. 421 o The sets of string classes need to be evaluated according to the 422 considerations that make up the headings in Section 3 423 o It is reasonable to limit scope to Unicode code points, and rule 424 the mapping of data from other character encodings outside the 425 scope of this effort. 427 Existing deployments already depend on Stringprep profiles. 428 Therefore, the working group will need to consider the effects of any 429 new strategy on existing deployments. By way of comparison, it is 430 worth noting that some characters were acceptable in IDNA labels 431 under IDNA2003, but are not protocol-valid under IDNA2008 (and 432 conversely). Different implementers may make different decisions 433 about what to do in such cases; this could have interoperability 434 effects. The working group will need to trade better support for 435 different linguistic environments against the potential side effects 436 of backward incompatibility. 438 5. Security Considerations 440 This document merely states what problems are to be solved, and does 441 not define a protocol. There are undoubtedly security implications 442 of the particular results that will come from the work to be 443 completed. 445 6. IANA Considerations 447 This document has no actions for IANA. 449 7. Discussion home for this draft 451 This document is intended to define the problem space discussed on 452 the precis@ietf.org mailing list. 454 8. Acknowledgements 456 This document is the product of the PRECIS IETF Working Group, and 457 participants in that Working Group were helpful in addressing issues 458 with the text. 460 Specific contributions came from Alan DeKok, Alexey Melnikov, Peter 461 Saint-Andre, Dave Thaler, and Yoshiro Yoneya. 463 Dave Thaler provided the "buckets" insight in Section 3.1.1, central 464 to the organization of the problem. 466 9. Informative References 468 [NEWPREP] "Newprep BoF Meeting Minutes", March 2010. 470 [RFC3454] Hoffman, P. and M. Blanchet, "Preparation of 471 Internationalized Strings ("stringprep")", RFC 3454, 472 December 2002. 474 [RFC3490] Faltstrom, P., Hoffman, P., and A. Costello, 475 "Internationalizing Domain Names in Applications (IDNA)", 476 RFC 3490, March 2003. 478 [RFC3491] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep 479 Profile for Internationalized Domain Names (IDN)", 480 RFC 3491, March 2003. 482 [RFC3492] Costello, A., "Punycode: A Bootstring encoding of Unicode 483 for Internationalized Domain Names in Applications 484 (IDNA)", RFC 3492, March 2003. 486 [RFC3530] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., 487 Beame, C., Eisler, M., and D. Noveck, "Network File System 488 (NFS) version 4 Protocol", RFC 3530, April 2003. 490 [RFC3722] Bakke, M., "String Profile for Internet Small Computer 491 Systems Interface (iSCSI) Names", RFC 3722, April 2004. 493 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. 494 Levkowetz, "Extensible Authentication Protocol (EAP)", 495 RFC 3748, June 2004. 497 [RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence 498 Protocol (XMPP): Core", RFC 3920, October 2004. 500 [RFC3922] Saint-Andre, P., "Mapping the Extensible Messaging and 501 Presence Protocol (XMPP) to Common Presence and Instant 502 Messaging (CPIM)", RFC 3922, October 2004. 504 [RFC4011] Waldbusser, S., Saperia, J., and T. Hongal, "Policy Based 505 Management MIB", RFC 4011, March 2005. 507 [RFC4013] Zeilenga, K., "SASLprep: Stringprep Profile for User Names 508 and Passwords", RFC 4013, February 2005. 510 [RFC4279] Eronen, P. and H. Tschofenig, "Pre-Shared Key Ciphersuites 511 for Transport Layer Security (TLS)", RFC 4279, 512 December 2005. 514 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 515 RFC 4314, December 2005. 517 [RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and 518 Security Layer (SASL)", RFC 4422, June 2006. 520 [RFC4505] Zeilenga, K., "Anonymous Simple Authentication and 521 Security Layer (SASL) Mechanism", RFC 4505, June 2006. 523 [RFC4511] Sermersheim, J., "Lightweight Directory Access Protocol 524 (LDAP): The Protocol", RFC 4511, June 2006. 526 [RFC4513] Harrison, R., "Lightweight Directory Access Protocol 527 (LDAP): Authentication Methods and Security Mechanisms", 528 RFC 4513, June 2006. 530 [RFC4518] Zeilenga, K., "Lightweight Directory Access Protocol 531 (LDAP): Internationalized String Preparation", RFC 4518, 532 June 2006. 534 [RFC4616] Zeilenga, K., "The PLAIN Simple Authentication and 535 Security Layer (SASL) Mechanism", RFC 4616, August 2006. 537 [RFC4643] Vinocur, J. and K. Murchison, "Network News Transfer 538 Protocol (NNTP) Extension for Authentication", RFC 4643, 539 October 2006. 541 [RFC4683] Park, J., Lee, J., Lee, H., Park, S., and T. Polk, 542 "Internet X.509 Public Key Infrastructure Subject 543 Identification Method (SIM)", RFC 4683, October 2006. 545 [RFC4690] Klensin, J., Faltstrom, P., Karp, C., and IAB, "Review and 546 Recommendations for Internationalized Domain Names 547 (IDNs)", RFC 4690, September 2006. 549 [RFC4790] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet 550 Application Protocol Collation Registry", RFC 4790, 551 March 2007. 553 [RFC4954] Siemborski, R. and A. Melnikov, "SMTP Service Extension 554 for Authentication", RFC 4954, July 2007. 556 [RFC5034] Siemborski, R. and A. Menon-Sen, "The Post Office Protocol 557 (POP3) Simple Authentication and Security Layer (SASL) 558 Authentication Mechanism", RFC 5034, July 2007. 560 [RFC5051] Crispin, M., "i;unicode-casemap - Simple Unicode Collation 561 Algorithm", RFC 5051, October 2007. 563 [RFC5054] Taylor, D., Wu, T., Mavrogiannopoulos, N., and T. Perrin, 564 "Using the Secure Remote Password (SRP) Protocol for TLS 565 Authentication", RFC 5054, November 2007. 567 [RFC5122] Saint-Andre, P., "Internationalized Resource Identifiers 568 (IRIs) and Uniform Resource Identifiers (URIs) for the 569 Extensible Messaging and Presence Protocol (XMPP)", 570 RFC 5122, February 2008. 572 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 573 Housley, R., and W. Polk, "Internet X.509 Public Key 574 Infrastructure Certificate and Certificate Revocation List 575 (CRL) Profile", RFC 5280, May 2008. 577 [RFC5456] Spencer, M., Capouch, B., Guy, E., Miller, F., and K. 578 Shumard, "IAX: Inter-Asterisk eXchange Version 2", 579 RFC 5456, February 2010. 581 [RFC5661] Shepler, S., Eisler, M., and D. Noveck, "Network File 582 System (NFS) Version 4 Minor Version 1 Protocol", 583 RFC 5661, January 2010. 585 [RFC5802] Newman, C., Menon-Sen, A., Melnikov, A., and N. Williams, 586 "Salted Challenge Response Authentication Mechanism 587 (SCRAM) SASL and GSS-API Mechanisms", RFC 5802, July 2010. 589 [RFC5804] Melnikov, A. and T. Martin, "A Protocol for Remotely 590 Managing Sieve Scripts", RFC 5804, July 2010. 592 [RFC5890] Klensin, J., "Internationalized Domain Names for 593 Applications (IDNA): Definitions and Document Framework", 594 RFC 5890, August 2010. 596 [RFC5891] Klensin, J., "Internationalized Domain Names in 597 Applications (IDNA): Protocol", RFC 5891, August 2010. 599 [RFC5892] Faltstrom, P., "The Unicode Code Points and 600 Internationalized Domain Names for Applications (IDNA)", 601 RFC 5892, August 2010. 603 [RFC5893] Alvestrand, H. and C. Karp, "Right-to-Left Scripts for 604 Internationalized Domain Names for Applications (IDNA)", 605 RFC 5893, August 2010. 607 [RFC5894] Klensin, J., "Internationalized Domain Names for 608 Applications (IDNA): Background, Explanation, and 609 Rationale", RFC 5894, August 2010. 611 [RFC5895] Resnick, P. and P. Hoffman, "Mapping Characters for 612 Internationalized Domain Names in Applications (IDNA) 613 2008", RFC 5895, September 2010. 615 [UAX15] "Unicode Standard Annex #15: Unicode Normalization Forms", 616 UAX 15, September 2009. 618 Appendix A. Protocols known to be using Stringprep 620 [[anchor21: This is where I'm supposed to have put the stuff already 621 in trac. --ajs@crankycanuck.ca]] 623 Appendix B. Changes between versions 625 Note to RFC Editor: This section should be removed prior to 626 publication. 628 B.1. 00 630 First WG version. Based on 631 draft-blanchet-precis-problem-statement-00. 633 B.2. 01 635 o Made clear that the document is talking only about Unicode code 636 points, and not any particular encoding. 637 o Substantially reorganized the document along the lines of the 638 review template at . 640 o Included specific questions for each topic for consideration. 641 o Moved spot for individual protocol review to appendix. Not 642 populated yet. 644 Authors' Addresses 646 Marc Blanchet 647 Viagenie 648 2600 boul. Laurier, suite 625 649 Quebec, QC G1V 4W1 650 Canada 652 Email: Marc.Blanchet@viagenie.ca 653 URI: http://viagenie.ca 655 Andrew Sullivan 656 519 Maitland St. 657 London, ON N6B 2Z5 658 Canada 660 Email: ajs@crankycanuck.ca