XML Security URIs: Additional XML Security Uniform Resource Identifiers (URIs)

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

       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].

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:

   <DigestAlgorithm
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#md5"/>

   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:

   <DigestAlgorithm
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#sha224" />

   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:

   <DigestAlgorithm
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#sha384" />

   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:

   <SignatureMethod
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#hmac-md5">
      <HMACOutputLength>112</HMACOutputLength>
   </SignatureMethod>

   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:

      <simpleType name="HMACOutputLength">
         <restriction base="integer" />
      </simpleType>

   DTD:

      <!ELEMENT HMACOutputLength (#PCDATA) >

   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.

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

   <SignatureMethod
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-md5" />

   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
   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:

   <SignatureMethod
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256" />

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:

   <SignatureMethod
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha384" />

   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:

   <SignatureMethod
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha512" />

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:

   <SignatureMethod
     Algorithm="http://www.w3.org/2001/04/xmldsig-more/rsa-ripemd160" />

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:

   <SignatureMethod
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#esign-sha1" />

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]:

   <Transform
      Algorithm="http://www.w3.org/2001/04/xmldsig-more/xptr">
      <XPointer
         xmlns="http://www.w3.org/2001/04/xmldsig-more/xptr">
            xpointer(id("foo")) xmlns(bar=http://foobar.example)
            xpointer(//bar:Zab[@Id="foo"])
      </XPointer>
   </Transform>

   Schema Definition:

      <element name="XPointer" type="string">

   DTD:

      <!ELEMENT XPointer (#PCDATA) >

   Input to this transform is an octet stream (which is then parsed into
   XML).

   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

   <EncryptionMethod
      Algorithm="http://www.w3.org/2001/04/xmldsig-more#arcfour">
      <KeySize>40</KeySize>
   </EncryptionMethod>

   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:

   <EncryptionMethod
      Algorithm=
      "http://www.w3.org/2001/04/xmldsig-more#camellia128-cbc" />

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:

   <EncryptionMethod
      Algorithm=
      "http://www.w3.org/2001/04/xmldsig-more#kw-camellia128" />

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:

   <EncryptionMethod
      Algorithm="http://www.w3.org/2001/04/xmlenc#psec-kem">
      <ECParameters>
         <Version>version</Version>
         <FieldID>id</FieldID>
         <Curve>curve</Curve>
         <Base>base</Base>
         <Order>order</Order>
         <Cofactor>cofactor</Cofactor>
      </ECParameters>
   </EncryptionMethod>

   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]:

   <foo:PKCS7signedData
      xmlns:foo="http://www.w3.org/2001/04/xmldsig-more">
      ...
   </foo:PKCS7signedData>

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

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.

   [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.

   [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.
                      <http://www.w3.org/TR/xmldsig-core/>

   [XMLENC]           "XML Encryption Syntax and Processing", J. Reagle,
                      D.  Eastlake, December 2002.
                      <http://www.w3.org/TR/2001/RED-xmlenc-core-
                      20021210/>

   [XPointer]         "XML Pointer Language (XPointer) Version 1.0", W3C
                      working draft, Steve DeRose, Eve Maler, Ron Daniel
                      Jr., January 2001.
                      <http://www.w3.org/TR/2001/WD-xptr-20010108>

Informative References

   [CANON]            "Canonical XML Version 1.0", John Boyer.
                      <http://www.w3.org/TR/2001/REC-xml-c14n-20010315>.

   [EXCANON]          "Exclusive XML Canonicalization Version 1.0", D.
                      Eastlake, J. Reagle, 18 July 2002.
                      <http://www.w3.org/TR/REC-xml-enc-c14n-20020718/>.

   [RFC3076]          Boyer, J., "Canonical XML Version 1.0", RFC 3076,
                      March 2001.

   [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

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