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RFC 2119 keyword, line 112: '...The XML namespace [XML-ns] URI that MUST be used by implementations of...' RFC 2119 keyword, line 141: '...definition of the entity Key.ANY SHOULD replace the one in [XMLDSIG]:...' RFC 2119 keyword, line 200: '...[X9.62], [FIPS-186-2] or [SEC2], the OIDs of these curves SHOULD be used...' Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (April 2003) is 6975 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) == Missing Reference: 'FIPS186-2' is mentioned on line 84, but not defined == Missing Reference: 'NIST-ECC' is mentioned on line 476, but not defined -- Possible downref: Non-RFC (?) normative reference: ref. 'FIPS-180-1' -- Possible downref: Non-RFC (?) normative reference: ref. 'FIPS-186-2' -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE1363' -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE1363a' -- Possible downref: Non-RFC (?) normative reference: ref. 'KEYS' ** Downref: Normative reference to an Informational RFC: RFC 3061 -- Possible downref: Non-RFC (?) normative reference: ref. 'SEC1' -- Possible downref: Non-RFC (?) normative reference: ref. 'SEC2' -- Possible downref: Non-RFC (?) normative reference: ref. 'XML' -- Possible downref: Non-RFC (?) normative reference: ref. 'XMLDSIG' -- Possible downref: Non-RFC (?) normative reference: ref. 'XML-ns' -- Possible downref: Non-RFC (?) normative reference: ref. 'XML-schema' Summary: 9 errors (**), 0 flaws (~~), 4 warnings (==), 13 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 INTERNET-DRAFT S. Blake-Wilson, BCI 2 G. Karlinger, CIO Austria 3 T. Kobayashi, NTT 4 Y. Wang, UNCC 5 Expires: October 2003 April 2003 7 ECDSA with XML-Signature Syntax 8 10 Status of this Memo 12 This document is an Internet-Draft and is in full conformance with all 13 provisions of Section 10 of RFC2026. Internet-Drafts are working 14 documents of the Internet Engineering Task Force (IETF), its areas, 15 and its working groups. Note that other groups may also distribute 16 working documents as Internet-Drafts. 18 Internet-Drafts are draft documents valid for a maximum of six months 19 and may be updated, replaced, or obsoleted by other documents at any 20 time. It is inappropriate to use Internet-Drafts as reference material 21 or to cite them other than as "work in progress." 23 The list of current Internet-Drafts may be found at 24 http://www.ietf.org/ietf/1id-abstracts.txt 26 The list of Internet-Draft Shadow Directories may be found at 27 http://www.ietf.org/shadow.html. 29 Abstract 31 This document specifies how to use ECDSA (Elliptic Curve Digital 32 Signature Algorithm) with XML Signatures [XMLDSIG]. The mechanism 33 specified provides integrity, message authentication, and/or signer 34 authentication services for data of any type, whether located 35 within the XML that includes the signature or included by reference. 37 Table of Contents 39 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 40 2 ECDSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 41 3 Specifying ECDSA within XMLDSIG . . . . . . . . . . . . . . . . 3 42 3.1 Version, Namespaces and Identifiers . . . . . . . . . . . . 3 43 3.2 XML Schema Preamble and DTD Replacement . . . . . . . . . . 4 44 3.2.1 XML Schema Preamble . . . . . . . . . . . . . . . . . 4 45 3.2.2 DTD Replacement . . . . . . . . . . . . . . . . . . . 4 46 3.3 ECDSA Signatures . . . . . . . . . . . . . . . . . . . . . 4 47 3.4 ECDSA Key Values . . . . . . . . . . . . . . . . . . . . . 4 48 3.4.1 Key Value Root Element . . . . . . . . . . . . . . . 4 49 3.4.2 EC Domain Parameters . . . . . . . . . . . . . . . . 5 50 3.4.2.1 Field Parameters . . . . . . . . . . . . . 6 51 3.4.2.2 Curve Parameters . . . . . . . . . . . . . 8 52 3.4.2.3 Base Point Parameters . . . . . . . . . . . 8 53 3.4.3 EC Points . . . . . . . . . . . . . . . . . . . . . 9 55 4 Security Considerations . . . . . . . . . . . . . . . . . . . . 10 56 5 Intellectual Property Rights . . . . . . . . . . . . . . . . . . 10 57 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 58 7 Authors' addresses . . . . . . . . . . . . . . . . . . . . . . . 12 59 8 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12 60 9 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 12 62 Appendix A: Aggregate XML Schema . . . . . . . . . . . . . . . . . 13 63 Appendix B: Aggregate DTD . . . . . . . . . . . . . . . . . . . . . 16 65 1. Introduction 67 This document specifies how to use the Elliptic Curve Digital Signature 68 Algorithm (ECDSA) with XML signatures as specified in [XMLDSIG]. Therein 69 only two digital signature methods are defined: RSA signatures and DSA 70 (DSS) signatures. This document introduces ECDSA signatures as an 71 additional method. 73 This document uses both XML Schemas [XML-schema] (normative) and DTDs 74 [XML] (informational) for specifying the corresponding XML structures. 76 2. ECDSA 78 The Elliptic Curve Digital Signature Algorithm (ECDSA) is the elliptic 79 curve analogue of the DSA (DSS) signature method [FIPS186-2]. It is 80 defined in the ANSI X9.62 standard [X9.62]. Other compatible 81 specifications include FIPS 186-2 [FIPS186-2], IEEE 1363 [IEEE1363], 82 IEEE 1363a [IEEE1363a], and SEC1 [SEC1]. [RFC3279] describes the means 83 to carry ECDSA keys in X.509 certificates. Recommended elliptic curve 84 domain parameters for use with ECDSA are given in [FIPS186-2], [SEC2], 85 and [X9.62]. 87 Like DSA, ECDSA incorporates the use of a hash function. Currently,the 88 only hash function defined for use with ECDSA is the SHA-1 message 89 digest algorithm [FIPS-180-1]. 91 ECDSA signatures are smaller than RSA signatures of similar 92 cryptographic strength. ECDSA public keys (and certificates) are smaller 93 than similar strength DSA keys, resulting in improved communications 94 efficiency. Furthermore, on many platforms ECDSA operations can be 95 computed faster than similar strength RSA or DSA operations (see [KEYS] 96 for a security analysis of key sizes across public key algorithms). 97 These advantages of signature size, bandwidth, and computational 98 efficiency may make ECDSA an attractive choice for XMLDSIG 99 implementations. 101 3. Specifying ECDSA within XMLDSIG 103 This section specifies the details of how to use ECDSA with XML 104 Signature Syntax and Processing [XMLDSIG]. It relies heavily on the 105 syntax and namespace defined therein. 107 3.1 Version, Namespaces and Identifiers 109 No provision is made for an explicit version number in this syntax. If 110 a future version is needed, it will use a different namespace. 112 The XML namespace [XML-ns] URI that MUST be used by implementations of 113 this (dated) specification is: 114 http://www.w3.org/2001/04/xmldsig-more# 116 Elements in the namespace of the [XMLDSIG] specification are marked as 117 such by using the namespace prefix "dsig" in the remaining sections of 118 this document. 120 The identifier for the ECDSA signature algorithm is: 121 http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha1 123 3.2 XML Schema Preamble and DTD Replacement 125 3.2.1 XML Schema Preamble 127 The subsequent preamble is to be used with the XML Schema definitions 128 given in the remaining sections of this document. 130 131 138 3.2.2 DTD Replacement 140 In order to include ECDSA in XML-signature syntax, the following 141 definition of the entity Key.ANY SHOULD replace the one in [XMLDSIG]: 143 145 3.3 ECDSA Signatures 147 The input to the ECDSA algorithm is the canonicalized representation of 148 the dsig:SignedInfo element as specified in Section 3 of [XMLDSIG]. 150 The output of the ECDSA algorithm consists of a pair of integers usually 151 referred by the pair (r, s). The signature value (text value of element 152 dsig:SignatureValue - see section 4.2 of [XMLDSIG]) consists of the 153 base64 encoding of the concatenation of two octet-streams that 154 respectively result from the octet-encoding of the values r and s. This 155 concatenation is described in section E3.1 of [IEEE1363]. 157 3.4 ECDSA Key Values 159 The syntax used for ECDSA key values closely follows the ASN.1 syntax 160 defined in ANSI X9.62 [X9.62]. 162 3.4.1 Key Value Root Element 164 The element ECDSAKeyValue is used for encoding ECDSA public keys. For 165 use with XMLDSIG simply use this element inside dsig:KeyValue, such as 166 the predefined elements dsig:RSAKeyValue or dsig:DSAKeyValue. 168 The element consists of an optional subelement DomainParameters and the 169 mandatory subelement PublicKey. If Domainparameters is missing in an 170 instance, this means that the application knows about them from other 171 means (implicitly). 173 Schema Definition: 175 177 178 179 181 182 183 185 DTD Definition: 187 188 189 190 191 192 194 3.4.2 EC Domain Parameters 196 Domain parameters can be encoded either explicitly using element 197 ExplicitParams, or by reference using element NamedCurve. The latter 198 simply consists of an attribute named URN, which bears a uniform 199 resource name as its value. For the named curves of standards like 200 [X9.62], [FIPS-186-2] or [SEC2], the OIDs of these curves SHOULD be used 201 in this attribute, e. g. URN="urn:oid:1.2.840.10045.3.1.1". The 202 mechanism for encoding OIDs in URNs is shown in [RFC3061]. 204 Schema Definition: 206 207 208 210 211 212 213 214 215 216 218 DTD Definition: 220 221 222 224 The element ExplicitParams is used for explicit encoding of domain 225 parameters. It contains three subelements: FieldParams describes the 226 underlying field, CurveParams describes the elliptic curve, and 227 BasePointParams describes the base point of the elliptic curve. 229 Schema Definition: 231 232 233 234 235 237 238 240 DTD Definition: 242 244 3.4.2.1 Field Parameters 246 The element FieldParams is used for encoding field parameters. The 247 corresponding XML Schema type FieldParamsType is declared abstract and 248 will be extended by specialized types for prime field, characteristic 249 two field and odd characteristic extension fields parameters. 251 The XML Schema type PrimeFieldParamsType is derived from FieldParamsType 252 and is used for for encoding prime field parameters. The type contains 253 as its single subelement P, the order of the prime field. 255 The XML Schema type CharTwoFieldParamsType is derived from 256 FieldParamsType as well and is used for encoding parameters of a 257 characteristic two field. It is again an abstract type and will be 258 extended by specialized types for trinomial base fields and pentanomial 259 base fields. F2m Gaussian Normal Base fields are not supported by this 260 specification to relieve interoperability. Common to both specialized 261 types is the element M, the extension degree of the field. 263 The XML Schema type TnBFieldParamsType is derived from 264 CharTwoFieldParamsType and is used for encoding trinomial base fields. 265 It adds the single element K, which represents the integer k, where 266 x^m + x^k + 1 is the reduction polynomial. 268 The XML Schema type PnBFieldParamsType is derived from 269 CharTwoFieldParamsType as well and is used for encoding pentanomial base 270 fields. It adds the three elements K1, K2 and K3, which represent the 271 integers k1, k2 and k3 respectively, where x^m + x^k3 + x^k2 + x^k1 + 1 272 is the reduction polynomial. 274 The XML Schema type OddCharExtensionFieldParamsType is derived from 275 FieldParamsType as well and is used for encoding parameters of an 276 odd characteristic extension field. The type contains two elements M, 277 which represents the extension degree of the field m, and W, which 278 represents the integer w, where x^m - w is the reduction polynomial. 280 Schema Definition: 282 284 285 286 287 288 289 290 291 292 294 295 296 297 298 299 300 301 302 304 305 306 307 308 309 310 311 312 313 315 316 317 318 319 320 321 322 323 325 326 327 328 329 330 331 333 334 335 336 338 DTD Definition: 340 341 342 343 344 345 346 347 349 3.4.2.2 Curve Parameters 351 The element CurveParams is used for encoding parameters of the elliptic 352 curve. The corresponding XML Schema type CurveParamsType bears the 353 elements A and B representing the coefficients a and b of the elliptic 354 curve, while the optional element Seed contains the value used to derive 355 the coefficients of a randomly generated elliptic curve, according to 356 the algorithm specified in annex A3.3 of [X9.62]. 358 Schema Definition: 360 361 362 363 364 365 366 368 DTD Definition: 370 371 372 373 374 375 377 3.4.2.3 Base Point Parameters 379 The element BasePointParams is used for encoding parameters regarding 380 the base point of the elliptic curve. BasePoint represents the base 381 point itself, Order provides the order of the base point, and Cofactor 382 optionally provides the cofactor of the base point. 384 Schema Definition: 386 387 388 389 390 392 393 395 DTD Definition: 397 398 399 400 402 3.4.3 EC Points 404 The XML Schema type ECPointType is used for encoding a point on the 405 elliptic curve. It consists of the subelements X and Y, providing the 406 x and y coordinates of the point. Point compression representation is 407 not supported by this specification for the sake of simple design. 409 The point at infinity is encoded by omitting both elements X and Y. 411 The subelements X and Y are of type FieldElemType. This is an abstract 412 type for encoding elements of the elliptic curves underlying field and 413 is extended by specialized types for prime field elements and 414 characteristic two field elements. 416 The XML Schema type PrimeFieldElemType is used for encoding prime field 417 elements. It contains a single attribute named Value, whose value 418 represents the field element as an integer. 420 The XML Schema type CharTwoFieldElemType is used for encoding 421 characteristic two field elements. It contains a single attribute named 422 Value, whose value represents the field element as an octet string. The 423 octet string must be composed as shown in paragraph 2 of section 4.3.3 424 of [X9.62]. 426 The XML Schema type OddCharExtensionFieldElemType is used for encoding 427 odd characteristic extension field elements. It contains a single 428 attribute named Value, whose value represents the field element as an 429 integer. The integer must be composed as shown in section 430 5.3.3 of [IEEE1363a]. 432 Schema Definition: 434 435 436 437 438 439 440 442 443 444 445 447 448 449 451 452 453 454 456 457 458 460 461 462 463 465 466 467 469 4. Security Considerations 471 Implementers should ensure that appropriate security measures are in 472 place when they deploy ECDSA within XMLDSIG. In particular, the security 473 of ECDSA requires the careful selection of both key sizes and elliptic 474 curve domain parameters. Selection guidelines for these parameters and 475 some specific recommended curves that are considered safe are provided 476 in [X9.62], [NIST-ECC], and [SEC2]. For further security discussion, 477 see [XMLDSIG]. 479 5. Intellectual Property Rights 481 The IETF has been notified of intellectual property rights claimed in 482 regard to the specification contained in this document. 483 For more information, consult the online list of claimed rights 484 (http://www.ietf.org/ipr.html). 486 The IETF takes no position regarding the validity or scope of any 487 intellectual property or other rights that might be claimed to 488 pertain to the implementation or use of the technology described in 489 this document or the extent to which any license under such rights 490 might or might not be available; neither does it represent that it 491 has made any effort to identify any such rights. Information on the 492 IETF's procedures with respect to rights in standards-track and 493 standards-related documentation can be found in BCP-11. Copies of 494 claims of rights made available for publication and any assurances of 495 licenses to be made available, or the result of an attempt made to 496 obtain a general license or permission for the use of such 497 proprietary rights by implementers or users of this specification can 498 be obtained from the IETF Secretariat. 500 6. References 502 [FIPS-180-1] Federal Information Processing Standards Publication 503 (FIPS PUB) 180-1, Secure Hash Standard, April 1995. 505 [FIPS-186-2] Federal Information Processing Standards Publication 506 (FIPS PUB) 186-2, Digital Signature Standard, January 507 2000. 509 [IEEE1363] Institute for Electrical and Electronics Engineers (IEEE) 510 Standard 1363-2000, Standard Specifications for Public Key 511 Cryptography, January 2000. 513 [IEEE1363a] Institute for Electrical and Electronics Engineers (IEEE) 514 Standard 1363, Draft Standard Specifications for Public 515 Key Cryptography -- Amendment 1: Additional Techniques, 516 October 2002. 518 [KEYS] Lenstra, A.K. and Verheul, E.R., Selecting Cryptographic Key 519 Sizes. October 1999. Presented at Public Key Cryptography 520 Conference, Melbourne, Australia, January 2000. 521 http://www.cryptosavvy.com/ 523 [RFC3061] Mealling, M., RFC 3061, A URN Namespace of Object 524 Identifiers. IETF Informational RFC, February 2001. 525 http://www.ietf.org/rfc/rfc3061.txt 527 [RFC3279] Bassham, L., Housley, R., and Polk, W., RFC 3279, Algorithms 528 and Identifiers for the Internet X.509 Public Key 529 Infrastructure Certificate and Certificate Revocation List 530 (CRL) Profile. IETF Proposed Standard, April 2002. 531 http://www.ietf.org/rfc/rfc3279.txt 533 [SEC1] Standards for Efficient Cryptography Group, SEC 1: Elliptic 534 Curve Cryptography, Version 1.0, September 2000. 535 http://www.secg.org 537 [SEC2] Standards for Efficient Cryptography Group, SEC 2: Recommended 538 Elliptic Curve Domain Parameters, Version 1.0, September 2000. 539 http://www.secg.org 541 [X9.62] American National Standards Institute. ANSI X9.62-1998, 542 Public Key Cryptography for the Financial Services Industry: 543 The Elliptic Curve Digital Signature Algorithm. January 1999. 545 [XML] Bray, T., Maler, E., Paoli, J. , and Sperberg-McQueen, C. M., 546 Extensible Markup Language (XML) 1.0 (Second Edition), W3C 547 Recommendation, October 2000. 548 http://www.w3.org/TR/2000/REC-xml-20001006 550 [XMLDSIG] Eastlake, D., Reagle, J., and Solo, D., XML-Signature 551 Syntax and Processing. W3C Recommendation, February 2002. 552 http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/ 554 [XML-ns] Bray, T., Hollander, D., and Layman, A., Namespaces in XML, 555 W3C Recommendation, January 1999. 556 http://www.w3.org/TR/1999/REC-xml-names-19990114/ 558 [XML-schema] Beech, D., Maloney, M., Mendelsohn, N., and Thompson, 559 H., XML Schema Part 1: Structures, W3C Recommendation, 560 May 2001. 561 http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/ 562 Biron, P., and Malhotra, A., ML Schema Part 2: 563 Datatypes, W3C Recommendation, May 2001. 564 http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/ 566 7. Authors' Addresses 568 Simon Blake-Wilson 569 BCI 570 96 Spadina Ave, Unit 606 571 Toronto, ON, M5V 2J6, Canada 572 e-mail: sblakewilson@bcisse.com 574 Gregor Karlinger 575 Chief Information Office Austria 576 Parkring 10/I/5 577 1010 Wien, Austria 578 e-mail: gregor.karlinger@cio.gv.at 580 Tetsutaro Kobayashi 581 NTT Laboratories 582 1-1 Hikarinooka, Yokosuka, 239-0847, Japan 583 e-mail: kotetsu@isl.ntt.co.jp 585 Yongge Wang 586 University of North Carolina at Charlotte 587 9201 University City Blvd 588 Charlotte, NC 28223, USA 589 e-mail: yonwang@uncc.edu 591 8. Acknowledgements 593 The authors would like to acknowledge the many helpful comments of 594 Wolfgang Bauer, Donald Eastlake, Tom Gindin, Chris Hawk, Akihiro Kato, 595 Shiho Moriai, Joseph M. Reagle Jr., and Francois Rousseau. 597 9. Full Copyright Statement 599 Copyright (C) The Internet Society (1999). All Rights Reserved. 601 This document and translations of it may be copied and furnished to 602 others, and derivative works that comment on or otherwise explain 603 it or assist in its implementation may be prepared, copied, 604 published and distributed, in whole or in part, without restriction 605 of any kind, provided that the above copyright notice and this 606 paragraph are included on all such copies and derivative works. 607 However, this document itself may not be modified in any way, such 608 as by removing the copyright notice or references to the Internet 609 Society or other Internet organizations, except as needed for the 610 purpose of developing Internet standards in which case the procedures 611 for copyrights defined in the Internet Standards process must be 612 followed, or as required to translate it into languages other than 613 English. 615 The limited permissions granted above are perpetual and will not be 616 revoked by the Internet Society or its successors or assigns. 618 This document and the information contained herein is provided on an 619 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 620 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 621 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 622 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 623 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 625 Appendix A: Aggregate XML Schema 627 628 637 639 640 641 642 644 645 646 648 650 651 652 654 655 656 657 658 659 660 661 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 710 711 712 713 714 715 716 718 719 720 721 722 723 724 725 726 727 728 729 730 731 733 734 736 738 739 740 741 742 743 745 747 748 749 750 751 753 754 755 756 757 758 759 761 762 763 764 765 766 767 769 770 771 772 774 Appendix B: Aggregate DTD 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803