INTERNET-DRAFT Donald E. Eastlake 3rd
Motorola Laboratories
Expires: July 2004 January 2004
Additional XML Security URIs
---------- --- -------- ----
<draft-eastlake-xmldsig-uri-05.txt>
Donald E. Eastlake 3rd
Status of This Document
Distribution of this document is unlimited. Comments should be sent
to the author and the XML Digital Signature mailing list <w3c-ietf-
xmldsig@w3.org>. This document is an Internet-Draft and is in full
conformance with all provisions of Section 10 of RFC 2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract
A number of URIs intended for use with XML Digital Signatures,
Encryption, and Canonnicalization are defined. These URIs identify
algorithms and types of keying information,
Acknowledgements
Glenn Adams, Merlin Hughs, Gregor Karlinger, Brian LaMachia, Shiho
Moriai, and Joseph Reagle.
D. Eastlake 3rd [Page 1]
INTERNET-DRAFT Additional XML Security URIs
Table of Contents
Status of This Document....................................1
Abstract...................................................1
Acknowledgements...........................................1
Table of Contents..........................................2
1. Introduction............................................3
2. Algorithms and Identifiers..............................4
2.1 DigestMethod Algorithms................................4
2.1.1 MD5..................................................4
2.1.2 SHA-384..............................................4
2.2 SignatureMethod Message Authentication Code Algorithms.5
2.2.1 HMAC-MD5.............................................5
2.2.2 HMAC SHA Variations..................................6
2.2.3 HMAC-RIPEMD160.......................................6
2.3 SignatureMethod Public Key Signature Algorithms........6
2.3.1 RSA-MD5..............................................7
2.3.2 RSA-SHA256...........................................8
2.3.3 RSA-SHA384...........................................8
2.3.4 RSA-SHA512...........................................8
2.3.5 RSA-RIPEMD160........................................8
2.3.6 ECDSA-SHA1...........................................9
2.3.7 ESIGN-SHA1...........................................9
2.4 Minimal Canonicalization...............................9
2.5 Transform Algorithms..................................10
2.5.1 XPointer............................................10
2.6 EncryptionMethod Algorithms...........................10
2.6.1 ARCFOUR Encryption Algorithm........................10
2.6.2 Camellia Block Encryption...........................11
2.6.3 Camellia Key Wrap...................................11
2.6.4 PSEC-KEM............................................12
3. KeyInfo................................................12
3.1 PKCS #7 Bag of Certificates and CRLs..................12
3.2 Additional RetrievalMethod Type Values................13
4. IANA Considerations....................................14
5. Security Considerations................................14
Normative References......................................15
Informative References....................................16
Author's Address..........................................17
Expiration and File Name..................................17
D. Eastlake 3rd [Page 2]
INTERNET-DRAFT Additional XML Security URIs
1. Introduction
XML Digital Signatures, Canonicalization, and Encryption have been
standardized by the W3C and by the joint IETF/W3C XMLDSIG working
group [W3C]. All of these are now W3C Recommendations and IETF
Inforamtional or Standards Track documents. They are available as
follows:
IETF level W3C REC Topic
----------- ------- -----
[RFC 3275] Draft Std [XMLDSIG] XML Digital Signatures
[RFC 3076] Info [CANON] Canonical XML
- - - - - - [XMLENC] XML Encryption
[EXCANON2] Info [EXCANON] Exclusive XML Canonicalization
All of these standards and recommendations use URIs to identify
algorithms and keying information types. This document is intended
to be a convenient reference list of URIs and descriptions for
algorithms in which there is substantial interest but which can not
or have not been included in the main documents for some reason.
Note in particular that raising XML digital signature to Draft
Standard in the IETF requires remove of any algorithms for which
there is not demonstrated interoperability from the main standards
document. This requires removal of the Minimal Canonicalization
algorithm, in which there appears to be continued interest, to be
dropped from the standards track specification. It is included here.
D. Eastlake 3rd [Page 3]
INTERNET-DRAFT Additional XML Security URIs
2. Algorithms and Identifiers
The URI being dropped from the standard due to the transition from
Proposed Standard to Draft Stanard is included herein with its
original
http://www.w3.org/2000/09/xmldsig#
prefix so as to avoid changing the XMLDSIG standard's namespace.
Additional algorithms, particularly those based on USA Government and
W3C standards, 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 nor does it imply that they are only
useful in digital signatures. Currently, dereferencing such URIs may
or may not produce a temporary placeholder document. Permission to
use these 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 [RFC 1321] takes no explicit parameters. An example
of an MD5 DigestAlgorithm element is:
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 [RFC 2045] encoding of this bit string
viewed as a 16-octet octet stream.
2.1.2 SHA-384
Identifier:
http://www.w3.org/2001/04/xmldsig-more#sha384
D. Eastlake 3rd [Page 4]
INTERNET-DRAFT Additional XML Security URIs
The SHA-384 algorithm [FIPS 180-2] takes no explicit parameters. An
example of a SHA-384 DigestAlgorithm element is:
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 [RFC2045] 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 [RFC 3275] for the
convenience of the reader.
2.2.1 HMAC-MD5
Identifier:
http://www.w3.org/2001/04/xmldsig-more#hmac-md5
The HMAC algorithm [RFC 2104] 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:
<SigntureMethod
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
[RFC 2405] encoded in the same straightforward fashion as the output
of the digest algorithms. Example: the SignatureValue element for the
HMAC-MD5 digest
9294727A 3638BB1C 13F48EF8 158BFC9D
from the test vectors in [RFC 2104] would be
kpRyejY4uxwT9I74FYv8nQ==
Schema Definition:
D. Eastlake 3rd [Page 5]
INTERNET-DRAFT Additional XML Security URIs
<simpleType name="HMACOutputLength">
<restriction base="integer">
</simpleType>
DTD:
<!ELEMENT HMACOutputLength (#PCDATA) >
The Schema Definition and DTD immediately above are copied from [RFC
3275].
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]
can also be used in HMAC as described in section 2.2.1 above 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 above for HMAC-MD5.
2.3 SignatureMethod Public Key Signature Algorithms
These algorithms are distinguished from those in Section 2.2 above in
that they use public key methods. That is to say, the verification
key is different from and not feasibly derivable from the signing
key.
D. Eastlake 3rd [Page 6]
INTERNET-DRAFT Additional XML Security URIs
2.3.1 RSA-MD5
Identifier:
http://www.w3.org/2001/04/xmldsig-more#rsa-md5
This implies the PKCS#1 v1.5 padding algorithm described in [RFC
2437].
An example of use is
<SignatureMethod
Algorthm="http://www.w3.org/2001/04/xmldsig-more#rsa-md5" />
The SignatureValue content for an RSA-MD5 signature is the base64
[RFC 2405] encoding of the octet string computed as per [RFC 2437],
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 [RFC 2437,
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 is 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
where "|" is concatentation, "01", "FF", and "00" are fixed octets of
the corresponding hexadecimal value, "hash" is the MD5 digest of the
data, and "prefix" is the ASN.1 BER MD5 algorithm designator prefix
required in PKCS #1 [RFC 2437], 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 make it easier to use standard
cryptographic libraries. The FF octet MUST be repeated the maximum
number of times such that the value of the quantity being CRYPTed is
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.
D. Eastlake 3rd [Page 7]
INTERNET-DRAFT Additional XML Security URIs
2.3.2 RSA-SHA256
Identifier:
http://www.w3.org/2001/04/xmldsig-more#rsa-sha256
An example of use is
<SignatureMethod
Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256" />
2.3.3 RSA-SHA384
Identifier:
ttp://www.w3.org/2001/04/xmldsig-more#rsa-sha384
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 it does 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
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 siganture method uses PKCS#1 padding as described in section
2.3.1. An example of use is
<SignatureMethod
Algorithm="http://www.w3.org/2001/04/xmldsig-more/rsa-ripemd160"
D. Eastlake 3rd [Page 8]
INTERNET-DRAFT Additional XML Security URIs
/>
2.3.6 ECDSA-SHA1
Identifier
http://www.w3.org/2001/04/xmldsig-more#ecdsa-sha1
The Elliptic Curve Digital Signature Algorith (ECDSA) [FIPS 186-2] is
the elliptic curve analogue of the DSA (DSS) signature method. For a
detailed specification of how to use it with XML Digital Signature,
please see [ECDSA].
2.3.7 ESIGN-SHA1
Identifier
http://www.w3.org/2001/04/xmldsig-more#esign-sha1
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 Siganture was advanced from Proposed Standard [RFC 3075] to
Draft Standard [RFC 3275], Minimal Canonicalization was dropped from
the standard track documents. However, there is still interest and
indicates of possible future use for Minimal Canonicalization. For
its definition, see [RFC 3075], Section 6.5.1.
For reference, it's identifier remains:
http://www.w3.org/2000/09/xmldsig#minimal
D. Eastlake 3rd [Page 9]
INTERNET-DRAFT Additional XML Security URIs
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:
<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=urn:baz)
xpointer(//bar:Zab[@Id="foo"])
</XPointer>
</Transform>
Schema Definition:
<element name="XPointer" type="string">
DTD:
<!ELEMENT XPointer (#PCDATA) >
Input to this transfrom 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 [RFC 3275] for
a same-document XPointer.
2.6 EncryptionMethod Algorithms
2.6.1 ARCFOUR Encryption Algorithm
Identifier:
http://www.w3.org/2001/04/xmldsgi-more#arcfour
D. Eastlake 3rd [Page 10]
INTERNET-DRAFT Additional XML Security URIs
ARCFOUR is a fast, simple stream encryption algorithm that is
compatible with RSA Security's RC4 algorithm. An example
EncryptionMethod element using ARCFOUR is
<EncryptionMethod
Algorithm="http://www.w3.org/2001/04/xmldsgi-more#arcfour">
<KeySize>40<KeySize>
</EncryptionMethod>
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 [RFC xxx3], 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
Camellia key wrap is identical to the AES key wrap algorithm [RFC
xxx4] specified in the XML Encryption standard with "AES" replaced by
"Camellia".
The algorithm is the same whatever 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 as to which combinations of KEK size and
wrapped key size are required to be supported and which are optional
to be supported should be followed. That is to say, if Camellia key
D. Eastlake 3rd [Page 11]
INTERNET-DRAFT Additional XML Security URIs
wrap is supported, they 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.
2.6.4 PSEC-KEM
Identifier:
http://www.w3.org/2001/04/xmldsgi-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>
3. KeyInfo
In section 3.1 below 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 [RFC 2315] "signedData" can also be used as a bag of
certificates and/or certificate revocation lists (CRLs). The
PKCS7signedData element is defined to accomodate such structures
within KeyInfo. The binary PKCS #7 strucuture is base64 [RFC 2405]
encoded. Any signer information present is ignored. The following
is a example, elliding the base64 data:
D. Eastlake 3rd [Page 12]
INTERNET-DRAFT Additional XML Security URIs
<foo:PKCS7signedData
xmlns="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 de-referencing 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 attibute because they are not unambiguously parseable.
Identifiers:
http://www.w3.org/2000/09/xmldsig-more#KeyValue
http://www.w3.org/2000/09/xmldsig-more#RetrievalMethod
http://www.w3.org/2000/09/xmldsig-more#KeyName
http://www.w3.org/2000/09/xmldsig-more#rawX509CRL
http://www.w3.org/2000/09/xmldsig-more#rawPGPKeyPacket
http://www.w3.org/2000/09/xmldsig-more#rawSPKISexp
http://www.w3.org/2000/09/xmldsig-more#PKCS7signedData
http://www.w3.org/2000/09/xmldsig-more#rawPKCS7signedData
D. Eastlake 3rd [Page 13]
INTERNET-DRAFT Additional XML Security URIs
4. IANA Considerations
None. As it is easy for people to construct their own unique URIs
and, possible, if appropriate, to obtain a URI from the W3C, it is
not intended that any additional "http://www.w3.org/2000/09/xmldsig-
more#" URIs be created.
5. Security Considerations
Due to computer speed and cryptographic advances, the use of MD5 as a
DigestMethod or in the RSA-MD5 SigantureMethod is NOT RECOMMENDED.
The cryrptographic advances concerned do not effect the security of
HMAC-MD5; however, there is little reason not to go for one of the
SHA series of algorithms.
D. Eastlake 3rd [Page 14]
INTERNET-DRAFT Additional XML Security URIs
Normative References
[Camellia] -
- "A Description of the Camellia Encryption Algorithm", M. Matsui, J.
Nakajima, S. Moriai, December 2003. draft-nakajima-camellia-03.txt
- "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 Aras in Cryptography, 7th Annual
International Workshop, SAC 2000, August 2000, Proceedings, Lecture
Notes in Computer Science 2012, pp. 39-56, Springer-Verlag, 2001.
[ECDSA] - "ECDSA with XML-Signature Syntax", S. Blake-Wilson, G.
Karlinger, T. Kobayashi, Y. Want, January 2004. draft-blake-wilson-
xmldsig-ecdsa-08.txt
[FIPS 180-1] - "Secure Hash Standard", (SHA-1) US Federal Information
Processing Standard, 17 April 1995.
[FIPS 180-2] - "Secure Hash Standard", (SHA-1/256/384/512) US Federal
Information Processing Standard, Draft, not yet issued.
[FIPS 180-2change] - "FIPS 180-2, Secure Hash Standard Change Notice
1", proposes adding SHA-224 to [FIPS 180-2].
[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.
[RFC 1321] - "The MD5 Message-Digest Algorithm", R. Rivest, April
1992.
[RFC 2104] - "HMAC: Keyed-Hashing for Message Authentication", H.
Krawczyk, M. Bellare, R. Canetti, February 1997.
[RFC 2405] - "Multipurpose Internet Mail Extensions (MIME) Part One:
Format of Internet Message Bodies", N. Freed, N. Borenstein, November
1996.
[RFC 2437] - "PKCS #1: RSA Cryptography Specifications Version 2.0",
B. Kaliski, J. Staddon, October 1998.
[RFC 2315] - "PKCS #7: Cryptographic Message Syntax Version 1.5", B.
Kaliski, March 1998.
D. Eastlake 3rd [Page 15]
INTERNET-DRAFT Additional XML Security URIs
[RFC 3075] - "XML-Signature Syntax and Processing", D. Eastlake, J.
Reagle, D. Solo, 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.)
[RFC 3275] - "XML-Signature Syntax and Processing", D. Eastlake, J.
Reagle, D. Solo, March 2002.
[RIPEMD-160] - ISO/IEC 10118-3:1998, "Information Technology -
Security techniques - Hash-functions - Part3: Dedicated hash-
functions", ISO, 1998.
[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/>.
[EXCANON2] - "Exclusive XML Canonicalization Version 1.0", D.
Eastlake, J. Reagle, December 2003, draft-ietf-xmldsig-xc14n-02.txt
[RFC 3076] - "Canonical XML Version 1.0", J. Boyer, March 2001.
[RFC 3092] - "Etymology of 'Foo'", D. Eastlake 3rd, C. Manros, E.
Raymond, 1 April 2001.
D. Eastlake 3rd [Page 16]
INTERNET-DRAFT Additional XML Security URIs
Author's Address
Donald E. Eastlake 3rd
Motorola Laboratories
155 Beaver Street
Milford, MA 01757 USA
Telephone: +1-508-786-7554 (w)
+1-508-634-2066 (h)
EMail: Donald.Eastlake@motorola.com
Expiration and File Name
This draft expires in July 2004.
Its file name is draft-eastlake-xmldsig-uri-05.txt
D. Eastlake 3rd [Page 17]
