Network Working Group D. Eastlake 3rd Request for Comments: 4051 Motorola Laboratories Category: Standards Track April 2005 Additional XML Security Uniform Resource Identifiers (URIs) Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2005). Abstract A number of Uniform Resource Identifiers (URIs) intended for use with XML Digital Signatures, Encryption, and Canonicalization are defined. These URIs identify algorithms and types of keying information. Table of Contents 1. Introduction.................................................. 2 2. Algorithms.................................................... 3 2.1. DigestMethod Algorithms................................. 3 2.1.1. MD5............................................. 3 2.1.2. SHA-224......................................... 3 2.1.3. SHA-384......................................... 4 2.2. SignatureMethod Message Authentication Code Algorithms.. 4 2.2.1. HMAC-MD5........................................ 4 2.2.2. HMAC SHA Variations............................. 5 2.2.3. HMAC-RIPEMD160.................................. 6 2.3. SignatureMethod Public Key Signature Algorithms......... 6 2.3.1. RSA-MD5......................................... 6 2.3.2. RSA-SHA256...................................... 7 2.3.3. RSA-SHA384...................................... 7 2.3.4. RSA-SHA512...................................... 7 2.3.5. RSA-RIPEMD160................................... 8 2.3.6. ECDSA-SHA*...................................... 8 2.3.7. ESIGN-SHA1...................................... 8 2.4. Minimal Canonicalization................................ 9 2.5. Transform Algorithms.................................... 9 2.5.1. XPointer........................................ 9 Eastlake 3rd Standards Track [Page 1] RFC 4051 Additional XML Security URIs April 2005 2.6. EncryptionMethod Algorithms............................. 10 2.6.1. ARCFOUR Encryption Algorithm.................... 10 2.6.2. Camellia Block Encryption....................... 10 2.6.3. Camellia Key Wrap............................... 11 2.6.4. PSEC-KEM........................................ 11 3. KeyInfo....................................................... 12 3.1. PKCS #7 Bag of Certificates and CRLs.................... 12 3.2. Additional RetrievalMethod Type Values.................. 12 4. IANA Considerations........................................... 13 5. Security Considerations....................................... 13 Acknowledgements.................................................. 13 Normative References.............................................. 13 Informative References............................................ 15 Author's Address.................................................. 16 Full Copyright Statement.......................................... 17 1. Introduction XML Digital Signatures, Canonicalization, and Encryption have been standardized by the W3C and the joint IETF/W3C XMLDSIG working group. All of these are now W3C Recommendations and IETF Informational or Standards Track documents. They are available as follows: IETF level W3C REC Topic ----------- ------- ----- [RFC3275] Draft Std [XMLDSIG] XML Digital Signatures [RFC3076] Info [CANON] Canonical XML - - - - - - [XMLENC] XML Encryption [RFC3741] Info [EXCANON] Exclusive XML Canonicalization All of these standards and recommendations use URIs [RFC2396] to identify algorithms and keying information types. This document provides a convenient reference list of URIs and descriptions for algorithms in which there is substantial interest, but which cannot or have not been included in the main documents. Note that raising XML digital signature to a Draft Standard in the IETF required removal of any algorithms for which interoperability from the main standards document has not been demonstrated. This required removal of the Minimal Canonicalization algorithm, in which there appears to be a continued interest, to be dropped from the standards track specification. It is included here. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Eastlake 3rd Standards Track [Page 2] RFC 4051 Additional XML Security URIs April 2005 2. Algorithms The URI [RFC2396] being dropped from the standard because of the transition from Proposed Standard to Draft Standard is included in Section 2.4 with its original prefix so as to avoid changing the XMLDSIG standard's namespace. http://www.w3.org/2000/09/xmldsig# Additional algorithms are given URIs that start with: http://www.w3.org/2001/04/xmldsig-more# An "xmldsig-more" URI does not imply any official W3C status for these algorithms or identifiers or that they are only useful in digital signatures. Currently, dereferencing such URIs may or may not produce a temporary placeholder document. Permission to use this URI prefix has been given by the W3C. 2.1. DigestMethod Algorithms These algorithms are usable wherever a DigestMethod element occurs. 2.1.1. MD5 Identifier: http://www.w3.org/2001/04/xmldsig-more#md5 The MD5 algorithm [RFC1321] takes no explicit parameters. An example of an MD5 DigestAlgorithm element is: An MD5 digest is a 128-bit string. The content of the DigestValue element shall be the base64 [RFC2405] encoding of this bit string viewed as a 16-octet octet stream. 2.1.2. SHA-224 Identifier: http://www.w3.org/2001/04/xmldsig-more#sha224 The SHA-224 algorithm [FIPS-180-2change, RFC3874] takes no explicit parameters. An example of a SHA-224 DigestAlgorithm element is: Eastlake 3rd Standards Track [Page 3] RFC 4051 Additional XML Security URIs April 2005 A SHA-224 digest is a 224 bit string. The content of the DigestValue element shall be the base64 [RFC2405] encoding of this string viewed as a 28-octet stream. Because it takes roughly the same amount of effort to compute a SHA-224 message digest as a SHA-256 digest, and terseness is usually not a criteria in an XML application, consideration should be given to the use of SHA-256 as an alternative. 2.1.3. SHA-384 Identifier: http://www.w3.org/2001/04/xmldsig-more#sha384 The SHA-384 algorithm [FIPS-180-2] takes no explicit parameters. An example of a SHA-384 DigestAlgorithm element is: A SHA-384 digest is a 384 bit string. The content of the DigestValue element shall be the base64 [RFC2405] encoding of this string viewed as a 48-octet stream. Because it takes roughly the same amount of effort to compute a SHA-384 message digest as a SHA-512 digest and terseness is usually not a criteria in XML application, consideration should be given to the use of SHA-512 as an alternative. 2.2. SignatureMethod Message Authentication Code Algorithms Note: Some text in this section is duplicated from [RFC3275] for the convenience of the reader. RFC 3275 is normative in case of conflict. 2.2.1. HMAC-MD5 Identifier: http://www.w3.org/2001/04/xmldsig-more#hmac-md5 The HMAC algorithm [RFC2104] takes the truncation length in bits as a parameter; if the parameter is not specified then all the bits of the hash are output. An example of an HMAC-MD5 SignatureMethod element is as follows: Eastlake 3rd Standards Track [Page 4] RFC 4051 Additional XML Security URIs April 2005 112 The output of the HMAC algorithm is ultimately the output (possibly truncated) of the chosen digest algorithm. This value shall be base64 [RFC2405] encoded in the same straightforward fashion as the output of the digest algorithms. For example, the SignatureValue element for the HMAC-MD5 digest 9294727A 3638BB1C 13F48EF8 158BFC9D from the test vectors in [RFC2104] would be kpRyejY4uxwT9I74FYv8nQ== Schema Definition: DTD: The Schema Definition and DTD immediately shown above are taken from [RFC3275]. Although some cryptographic suspicions have recently been cast on MD5 for use in signatures such as RSA-MD5 below, this does not effect use of MD5 in HMAC. 2.2.2. HMAC SHA Variations Identifiers: http://www.w3.org/2001/04/xmldsig-more#hmac-sha224 http://www.w3.org/2001/04/xmldsig-more#hmac-sha256 http://www.w3.org/2001/04/xmldsig-more#hmac-sha384 http://www.w3.org/2001/04/xmldsig-more#hmac-sha512 SHA-224, SHA-256, SHA-384, and SHA-512 [FIPS-180-2, FIPS-180-2change, RFC3874] can also be used in HMAC as described in section 2.2.1 for HMAC-MD5. Eastlake 3rd Standards Track [Page 5] RFC 4051 Additional XML Security URIs April 2005 2.2.3. HMAC-RIPEMD160 Identifier: http://www.w3.org/2001/04/xmldsig-more#hmac-ripemd160 RIPEMD-160 [RIPEMD-160] can also be used in HMAC as described in section 2.2.1 for HMAC-MD5. 2.3. SignatureMethod Public Key Signature Algorithms These algorithms are distinguished from those in Section 2.2 in that they use public key methods. The verification key is different from and not feasibly derivable from the signing key. 2.3.1. RSA-MD5 Identifier: http://www.w3.org/2001/04/xmldsig-more#rsa-md5 RSA-MD5 implies the PKCS#1 v1.5 padding algorithm described in [RFC3447]. An example of use is The SignatureValue content for an RSA-MD5 signature is the base64 [RFC2405] encoding of the octet string computed as per [RFC3447], section 8.1.1, signature generation for the RSASSA-PKCS1-v1_5 signature scheme. As specified in the EMSA-PKCS1-V1_5-ENCODE function in [RFC3447, section 9.2.1], the value input to the signature function MUST contain a pre-pended algorithm object identifier for the hash function, but the availability of an ASN.1 parser and recognition of OIDs are not required of a signature verifier. The PKCS#1 v1.5 representation appears as: CRYPT (PAD (ASN.1 (OID, DIGEST (data)))) Note that the padded ASN.1 will be of the following form: 01 | FF* | 00 | prefix | hash Vertical bar ("|") represents concatenation. "01", "FF", and "00" are fixed octets of the corresponding hexadecimal value and the asterisk ("*") after "FF" indicates repetition. "hash" is the MD5 digest of the data. "prefix" is the ASN.1 BER MD5 algorithm designator prefix required in PKCS #1 [RFC3447], that is: hex 30 20 30 0c 06 08 2a 86 48 86 f7 0d 02 05 05 00 04 10 Eastlake 3rd Standards Track [Page 6] RFC 4051 Additional XML Security URIs April 2005 This prefix is included to facilitate the use of standard cryptographic libraries. The FF octet MUST be repeated enough times that the value of the quantity being CRYPTed is exactly one octet shorter than the RSA modulus. Due to increases in computer processor power and advances in cryptography, use of RSA-MD5 is NOT RECOMMENDED. 2.3.2. RSA-SHA256 Identifier: http://www.w3.org/2001/04/xmldsig-more#rsa-sha256 This implies the PKCS#1 v1.5 padding algorithm [RFC3447] as described in section 2.3.1, but with the ASN.1 BER SHA-256 algorithm designator prefix. An example of use is: 2.3.3 RSA-SHA384 Identifier: http://www.w3.org/2001/04/xmldsig-more#rsa-sha384 This implies the PKCS#1 v1.5 padding algorithm [RFC3447] as described in section 2.3.1, but with the ASN.1 BER SHA-384 algorithm designator prefix. An example of use is: Because it takes about the same effort to calculate a SHA-384 message digest as a SHA-512 message digest, it is suggested that RSA-SHA512 be used in preference to RSA-SHA384 where possible. 2.3.4. RSA-SHA512 Identifier: http://www.w3.org/2001/04/xmldsig-more#rsa-sha512 This implies the PKCS#1 v1.5 padding algorithm [RFC3447] as described in section 2.3.1, but with the ASN.1 BER SHA-512 algorithm designator prefix. An example of use is: Eastlake 3rd Standards Track [Page 7] RFC 4051 Additional XML Security URIs April 2005 2.3.5. RSA-RIPEMD160 Identifier: http://www.w3.org/2001/04/xmldsig-more/rsa-ripemd160 This implies the PKCS#1 v1.5 padding algorithm [RFC3447], as described in section 2.3.1, but with the ASN.1 BER RIPEMD160 algorithm designator prefix. An example of use is: 2.3.6. ECDSA-SHA* Identifiers http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha1 http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha224 http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha256 http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha384 http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha512 The Elliptic Curve Digital Signature Algorithm (ECDSA) [FIPS-186-2] is the elliptic curve analogue of the DSA (DSS) signature method. For detailed specifications on how to use it with SHA hash functions and XML Digital Signature, please see [X9.62] and [ECDSA]. 2.3.7. ESIGN-SHA1 Identifier http://www.w3.org/2001/04/xmldsig-more#esign-sha1 http://www.w3.org/2001/04/xmldsig-more#esign-sha224 http://www.w3.org/2001/04/xmldsig-more#esign-sha256 http://www.w3.org/2001/04/xmldsig-more#esign-sha384 http://www.w3.org/2001/04/xmldsig-more#esign-sha512 The ESIGN algorithm specified in [IEEE-P1363a] is a signature scheme based on the integer factorization problem. It is much faster than previous digital signature schemes so ESIGN can be implemented on smart cards without special co-processors. An example of use is: Eastlake 3rd Standards Track [Page 8] RFC 4051 Additional XML Security URIs April 2005 2.4. Minimal Canonicalization Thus far two independent interoperable implementations of Minimal Canonicalization have not been announced. Therefore, when XML Digital Signature was advanced from Proposed Standard [RFC3075] to Draft Standard [RFC3275], Minimal Canonicalization was dropped from the standards track documents. However, there is still interest in Minimal Canonicalization, indicating its possible future use. For its definition, see [RFC3075], Section 6.5.1. For reference, its identifier remains: http://www.w3.org/2000/09/xmldsig#minimal 2.5. Transform Algorithms Note that all CanonicalizationMethod algorithms can also be used as transform algorithms. 2.5.1. XPointer Identifier: http://www.w3.org/2001/04/xmldsig-more/xptr This transform algorithm takes an [XPointer] as an explicit parameter. An example of use is [RFC3092]: xpointer(id("foo")) xmlns(bar=http://foobar.example) xpointer(//bar:Zab[@Id="foo"]) Schema Definition: DTD: Input to this transform is an octet stream (which is then parsed into XML). Eastlake 3rd Standards Track [Page 9] RFC 4051 Additional XML Security URIs April 2005 Output from this transform is a node set; the results of the XPointer are processed as defined in the XMLDSIG specification [RFC3275] for a same document XPointer. 2.6. EncryptionMethod Algorithms This subsection gives identifiers and information for several EncryptionMethod Algorithms. 2.6.1. ARCFOUR Encryption Algorithm Identifier: http://www.w3.org/2001/04/xmldsig-more#arcfour ARCFOUR is a fast, simple stream encryption algorithm that is compatible with RSA Security's RC4 algorithm. An example of the EncryptionMethod element using ARCFOUR is 40 Note that Arcfour makes use of the generic KeySize parameter specified and defined in [XMLENC]. 2.6.2. Camellia Block Encryption Identifiers: http://www.w3.org/2001/04/xmldsig-more#camellia128-cbc http://www.w3.org/2001/04/xmldsig-more#camellia192-cbc http://www.w3.org/2001/04/xmldsig-more#camellia256-cbc Camellia is an efficient and secure block cipher with the same interface as the AES [Camellia, RFC3713], that is 128-bit block size and 128, 192, and 256 bit key sizes. In XML Encryption, Camellia is used in the same way as the AES: It is used in the Cipher Block Chaining (CBC) mode with a 128-bit initialization vector (IV). The resulting cipher text is prefixed by the IV. If included in XML output, it is then base64 encoded. An example Camellia EncryptionMethod is as follows: Eastlake 3rd Standards Track [Page 10] RFC 4051 Additional XML Security URIs April 2005 2.6.3. Camellia Key Wrap Identifiers: http://www.w3.org/2001/04/xmldsig-more#kw-camellia128 http://www.w3.org/2001/04/xmldsig-more#kw-camellia192 http://www.w3.org/2001/04/xmldsig-more#kw-camellia256 The Camellia [Camellia, RFC3713] key wrap is identical to the AES key wrap algorithm [RFC3394] specified in the XML Encryption standard with "AES" replaced by "Camellia". As with AES key wrap, the check value is 0xA6A6A6A6A6A6A6A6. The algorithm is the same regardless of the size of the Camellia key used in wrapping (called the key encrypting key or KEK). The implementation of Camellia is OPTIONAL. However, if it is supported, the same implementation guidelines of which combinations of KEK size and wrapped key size should be required to be supported and which are optional to be supported should be followed as for AES. That is to say, if Camellia key wrap is supported, then wrapping 128-bit keys with a 128-bit KEK and wrapping 256-bit keys with a 256-bit KEK are REQUIRED and all other combinations are OPTIONAL. An example of use is: 2.6.4. PSEC-KEM Identifier: http://www.w3.org/2001/04/xmldsig-more#psec-kem The PSEC-KEM algorithm, specified in [ISO/IEC-18033-2], is a key encapsulation mechanism using elliptic curve encryption. An example of use is: version id curve base order cofactor Eastlake 3rd Standards Track [Page 11] RFC 4051 Additional XML Security URIs April 2005 See [ISO/IEC-18033-2] for information on the parameters above. 3. KeyInfo In section 3.1 a new KeyInfo element child is specified, while in section 3.2 additional KeyInfo Type values for use in RetrievalMethod are specified. 3.1. PKCS #7 Bag of Certificates and CRLs A PKCS #7 [RFC2315] "signedData" can also be used as a bag of certificates and/or certificate revocation lists (CRLs). The PKCS7signedData element is defined to accommodate such structures within KeyInfo. The binary PKCS #7 structure is base64 [RFC2405] encoded. Any signer information present is ignored. The following is an example, eliding the base64 data [RFC3092]: ... 3.2. Additional RetrievalMethod Type Values The Type attribute of RetrievalMethod is an optional identifier for the type of data to be retrieved. The result of dereferencing a RetrievalMethod reference for all KeyInfo types with an XML structure is an XML element or document with that element as the root. The various "raw" key information types return a binary value. Thus, they require a Type attribute because they are not unambiguously parseable. Identifiers: http://www.w3.org/2001/04/xmldsig-more#KeyValue http://www.w3.org/2001/04/xmldsig-more#RetrievalMethod http://www.w3.org/2001/04/xmldsig-more#KeyName http://www.w3.org/2001/04/xmldsig-more#rawX509CRL http://www.w3.org/2001/04/xmldsig-more#rawPGPKeyPacket http://www.w3.org/2001/04/xmldsig-more#rawSPKISexp http://www.w3.org/2001/04/xmldsig-more#PKCS7signedData http://www.w3.org/2001/04/xmldsig-more#rawPKCS7signedData Eastlake 3rd Standards Track [Page 12] RFC 4051 Additional XML Security URIs April 2005 4. IANA Considerations As it is easy for people to construct their own unique URIs [RFC2396] and possibly obtain a URI from the W3C if appropriate, it is not intended that any additional "http://www.w3.org/2001/04/xmldsig- more#" URIs be created beyond those enumerated in this document. (W3C Namespace stability rules prohibit the creation of new URIs under "http://www.w3.org/2000/09/xmldsig#".) 5. Security Considerations Due to computer speed and cryptographic advances, the use of MD5 as a DigestMethod and the use of MD5 in the RSA-MD5 SignatureMethod is NOT RECOMMENDED. The concerned cryptographic advances do not effect the security of HMAC-MD5; however, there is little reason not to use one of the SHA series of algorithms. Acknowledgements Glenn Adams, Merlin Hughs, Gregor Karlinger, Brian LaMachia, Shiho Moriai, Joseph Reagle, Russ Housley, and Joel Halpern. Normative References [Camellia] "Camellia: A 128-bit Block Cipher Suitable for Multiple Platforms - Design and Analysis -", K. Aoki, T. Ichikawa, M. Matsui, S. Moriai, J. Nakajima, T. Tokita, In Selected Areas in Cryptography, 7th Annual International Workshop, SAC 2000, August 2000, Proceedings, Lecture Notes in Computer Science 2012, pp. 39-56, Springer- Verlag, 2001. [ECDSA] Blake-Wilson, S., Karlinger, G., Kobayashi, T., and Y. Wang, "Using the Elliptic Curve Signature Algorithm (ECDSA) for XML Digital Signatures", RFC 4050, April 2005. [FIPS-180-2] "Secure Hash Standard", (SHA-1/256/384/512) US Federal Information Processing Standard, 1 August 2002. [FIPS-180-2change] "FIPS 180-2, Secure Hash Standard Change Notice 1", adds SHA-224 to [FIPS 180-2], 25 February 2004. [FIPS-186-2] "Digital Signature Standard", National Institute of Standards and Technology, 2000. Eastlake 3rd Standards Track [Page 13] RFC 4051 Additional XML Security URIs April 2005 [IEEE-P1363a] "Standard Specifications for Public Key Cryptography: Additional Techniques", October 2002. [ISO/IEC-18033-2] "Information technology -- Security techniques -- Encryption algorithms -- Part 3: Asymmetric ciphers", CD, October 2002. [RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm ", RFC 1321, April 1992. [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-Hashing for Message Authentication", RFC 2104, February 1997. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [RFC2405] Madson, C. and N. Doraswamy, "The ESP DES-CBC Cipher Algorithm With Explicit IV", RFC 2405, November 1998. [RFC2315] Kaliski, B., "PKCS #7: Cryptographic Message Syntax Version 1.5", RFC 2315, March 1998. [RFC3075] Eastlake 3rd, D., Reagle, J., and D. Solo, "XML- Signature Syntax and Processing", RFC 3075, March 2001. (RFC 3075 was obsoleted by RFC 3275 but is referenced in this document for its description of Minimal Canonicalization which was dropped in RFC 3275.) [RFC3275] Eastlake 3rd, D., Reagle, J., and D. Solo, "(Extensible Markup Language) XML-Signature Syntax and Processing", RFC 3275, March 2002. [RFC3394] Schaad, J. and R. Housley, "Advanced Encryption Standard (AES) Key Wrap Algorithm", RFC 3394, September 2002. Eastlake 3rd Standards Track [Page 14] RFC 4051 Additional XML Security URIs April 2005 [RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications Version 2.1", RFC 3447, February 2003. [RFC3713] Matsui, M., Nakajima, J., and S. Moriai, "A Description of the Camellia Encryption Algorithm", RFC 3713, April 2004. [RFC3874] Housley, R., "A 224-bit One-way Hash Function: SHA-224", RFC 3874, September 2004. [RIPEMD-160] ISO/IEC 10118-3:1998, "Information Technology - Security techniques - Hash-functions - Part3: Dedicated hash- functions", ISO, 1998. [X9.62] X9.62-200X, "Public Key Cryptography for the Financial Services Industry: The Elliptic Curve Digital Signature Algorithm (ECDSA)", Accredited Standards Committee X9, American National Standards Institute. [XMLDSIG] "XML-Signature Syntax and Processing", D. Eastlake 3rd, J. Reagle, & D. Solo, 12 February 2002. [XMLENC] "XML Encryption Syntax and Processing", J. Reagle, D. Eastlake, December 2002. [XPointer] "XML Pointer Language (XPointer) Version 1.0", W3C working draft, Steve DeRose, Eve Maler, Ron Daniel Jr., January 2001. Informative References [CANON] "Canonical XML Version 1.0", John Boyer. . [EXCANON] "Exclusive XML Canonicalization Version 1.0", D. Eastlake, J. Reagle, 18 July 2002. . [RFC3076] Boyer, J., "Canonical XML Version 1.0", RFC 3076, March 2001. Eastlake 3rd Standards Track [Page 15] RFC 4051 Additional XML Security URIs April 2005 [RFC3092] Eastlake 3rd, D., Manros, C., and E. Raymond, "Etymology of "Foo"", RFC 3092, 2001. [RFC3741] Boyer, J., Eastlake 3rd, D., and J. Reagle, "Exclusive XML Canonicalization, Version 1.0", RFC 3741, March 2004. Author's Address Donald E. Eastlake 3rd Motorola Laboratories 155 Beaver Street Milford, MA 01757 USA Phone: +1-508-786-7554 (w) +1-508-634-2066 (h) EMail: Donald.Eastlake@motorola.com Eastlake 3rd Standards Track [Page 16] RFC 4051 Additional XML Security URIs April 2005 Full Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Eastlake 3rd Standards Track [Page 17]