WDIFF

draft-eastlake-xmldsig-uri-00.txt --> draft-eastlake-xmldsig-uri-01.txt

INTERNET-DRAFT Donald Eastlake 3rd
Motorola
Expires: October 2001 April 2001

Additional XML Digital Signature URIs
---------- --- ------- --------- ----
<draft-eastlake-xmldsig-uri-00.txt>
<draft-eastlake-xmldsig-uri-01.txt>

Status of This Document

Distribution of this draft, which draft is unlimited. It is intended to become an
Informational RFC, is unlimited. RFC and will probably also be published as a W3C Note.
Comments should be sent to the author or the XMLDSIG working group
<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 algorithm URIs intended for use with XML Digital
Signatures [RFC 3075] are defined.

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Acknowledgements

Glenn Adams, Merlin Hughs, Brian LaMachia, Joseph Reagle

Table of Contents

Status of This Document....................................1
Copyright Notice...........................................1
Abstract...................................................1

Acknowledgements...........................................2
Table of Contents..........................................2

1. Introduction............................................3
2. URIs....................................................3
2.1 Message Digests........................................3 DigestMethod Algorithms................................3
2.1.1 MD5..................................................3
2.1.2 SHA-256..............................................4
2.1.3 SHA-512..............................................4
2.1.4 SHA-384..............................................4
2.1.4 SHA-512..............................................4
2.2 SignatureMethod Message Authentication Codes...........................5 Code Algorithms.5
2.2.1 HMAC-MD5.............................................5
2.2.2 HMAC-SHA-256.........................................6
2.2.3 HMAC-SHA-512.........................................6
2.2.4 HMAC-SHA-384.........................................6
2.2.4 HMAC-SHA-512.........................................6
2.3 SignatureMethod Public Key Signature Algorithms...................................7 Algorithms........6
2.3.1 RSA-MD5..............................................7
2.3.2 RSA-SHA-256..........................................7 RSA-SHA256...........................................8
2.3.3 RSA-SHA-512..........................................7 RSA-SHA384...........................................8
2.3.4 RSA-SHA-384..........................................7 RSA-SHA512...........................................8
2.4 Canonicalizaton Algorithms.............................7 CanonicalizatonMethod Algorithms.......................8
2.4.1 Minimal Canonicalization.............................7 Canonicalization.............................8
2.5 Transform Algorithms...................................8 Algorithms...................................9
2.5.1 XPointer.............................................9
3. IANA Considerations.....................................8 KeyInfo Elements.......................................10
3.1 PKCS #7 Bag of Certificates and CRLs..................10
4. IANA Considerations....................................10
5. Security Considerations.................................8

References.................................................9
Authors Addresses..........................................9

Full Copyright Statement..................................10 Considerations................................10

References................................................11

Author's Address..........................................12
Expiration and File Name..................................10 Name..................................12

Full Copyright Statement..................................13

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1. Introduction

XML Digital Signatures have been standardized by the joint IETF/W3C
XMLDSIG working group. The Proposed Standard is specified in [RFC
3075]. In addition, Canonical XML, which is used by many digital
signatures, has been standardized by the W3C and is documented in
Informational [RFC 3076].

[RFC 3075] specifies URIs to identify algorithms. However, this
ppotocol
protocol is likely to be raised to Draft Standard soon, which
requires two independent interoperable implementations to exist.
This may require algorithms in which there appears to be substantial continued
interest to be dropped. dropped from the standards track specification. This
document is intended as a convenient reference list of URIs and
descriptions for any dropped from the Proposed Standard due to lack
of implementations plus additional suggested algorithms in which
there appears to be substantial interest.

2. URIs

The sections below parallel those in Section 6 of RFC 3075 which
group various algorithms by there their use in XML Digital Sigantures.
URIs being dropped from the standard due to the transition from
Proposed Standard to Draft Stanard are included herein. Additional
non-proprietary algorithms, particularly those based on USA
Government and W3C standards, are given URIs that start with

http://www.w3.org/2001/04/xmldsig-more

This does not imply any official W3C status for these algorithms.
Currently, dereferencing such URIs produces, at best, a temporary
placeholder document. Permission to use these URIs was tentatively
given by W3C staff.

2.1 Message Digests DigestMethod Algorithms

2.1.1 MD5

Identifier:
http://md.xmldsig.ietf.arpa#md5
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:

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<DigestMethod Algorithm="http://md.xmldsig.ietf.arpa#md5"/>
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 [RFC 2045] encoding of this bit string
viewed as a 16-octet octet stream.

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2.1.2 SHA-256

Identifier:
http://md.xmldsig.ietf.arpa#sha256
http://www.w3.org/2001/04/xmldsig-more#sha256

The SHA-256 algorithm [SHA-256] takes no explicit parameters. An
example of a SHA-256 DigestAlgorithm element is:

<DigestMethod Algorithm="http://md.xmldsig.ietf.arpa#sha256/>
Algorithm="http://www.w3.org/2001/04/xmldsig-more#sha256/>

A SHA-256 disgest is a 256 bit string. The content of the
DigestValue element shall be the base64 [RFC 2045] encoding of this
string viewed as a 32-octet stream.

2.1.3 SHA-512 SHA-384

Identifier:
http://md.xmldsig.ietf.arpa#sha512
http://www.w3.org/2001/04/xmldsig-more#sha384

The SHA-512 SHA-384 algorithm [SHA-512] [SHA-384] takes an optional truncation
parameter, SHAtruncation, in the range 0 to 512. no explicit parameters. An
example of a
SHA-512 DigestAlgorithm SHA-384 DigestAlforithm element with such a parameter is:

<DigestMethod Algorith="http://md.xmldsig.ietf.arpa#sha512">
<SHAtruncation>400</SHAtruncation> </DigestMethod>
Algorith="http://www.w3.org/2001/04/xmldsig-more#sha384"/>

A SHA-512 SHA-384 digest is a 512 384 bit string except that, if string. The content of the
SHA512truncation parameter is present specifying truncation to n
bits, it is DigestValue
element shall be the left most n bits base64 [RFC2045] encoding of that string. In effect, the
truncation parameter defaults to 512.

Schema Definition:

DTD:

<!ELEMENT SHAtruncation (#PCDATA)> this string viewed
as a 48-octet stream.

2.1.4 SHA-384 SHA-512

Identifier:
http://md.xmldsig.ietf.arpa#sha384
http://www.w3.org/2001/04/xmldsig-more#sha512

The SHA-384 SHA-512 algorithm [SHA-384] [SHA-512] takes an optional truncation no explicit parameters. An
example of a SHA-512 DigestAlgorithm elementis:

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parameter, SHAtruncation, in the range 0 to 512. An example of a
SHA-384 DigestAlforithm element without such a parameter is:

<DigestMethod Algorith="http://md.xmldsig.ietf.arpa#sha384"/>
Algorithm="http://www.w3.org/2001/04/xmldsig-more#sha512"/>

A SHA-384 SHA-512 digest is the leftmost 384 bits of the a 512 bit string that
the algorithm calculates internally except that, if the SHAtruncation
parameter is present specifying truncation to n bits, it is the left
most n bits of that string. In effect, the truncation parameter
defaults to 384. (The SHA-384 algorithm has The content of the same internal
structure as DigestValue
element shall be the SHA-512 algorithm but a few different constants are
used, resulting in base64 [RFC2045] encoding of this string viewed
as a different 512 bit hasj value, and it is normally
truncated to 384 bits.

See Schema Definition and DTD for SHA-512 above. 64-octet stream.

2.2 SignatureMethod Message Authentication Codes Code Algorithms

Some text in this section is duplicated from RFC 3075 for the
convenience of the reader.

2.2.1 HMAC-MD5

Identifier:
http://mac.xmldsig.ietf.arpa#hmac-md5
http://www.w3.org/2001/04/xmldsig-more#hmac-md5

The HMAC algorithm (RFC2104 [HMAC]) [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 HMAC-MD5 SignatureMethod
element:
element is as follows:

<SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-
md5">
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
HMAC-MD5 digest

9294727A 3638BB1C 13F48EF8 158BFC9D

from the test vectors in [RFC 2104] would be

<SignatureValue>kpRyejY4uxwT9I74FYv8nQ==</SignatureValue>

Schema Definition:

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<SignatureValue>kpRyejY4uxwT9I74FYv8nQ==</SignatureValue>

Schema Definition:

DTD:

<!ELEMENT HMACOutputLength (#PCDATA)>

The Schema Definition and DTD immediately above are copied from RFC
3075.

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-256

Identifier:
http://mac.xmldsig.ietf.arpa#hmac-sha256
http://www.w3.org/2001/04/xmldsig-more#hmac-sha256

SHA-256 [SHA-256] can also be used in HMAC as described in section
2.2.1 above. above for HMAC-MD5.

2.2.3 HMAC-SHA-512 HMAC-SHA-384

Identifier:
http://mac.xmldsig.ietf.arpa#hmac-sha512

SHA-512 [SHA-512]
http://www.w3.org/2001/04/xmldsig-more#hmac-sha384

SHA-384 [SHA-384] can also be used in HMAC as describe described in section
2.2.1 above. above for HMAC-MD5.

2.2.4 HMAC-SHA-384 HMAC-SHA-512

Identifier:
http://mac.xmldsig.ietf.arpa#hmac-sha384

SHA-384 [SHA-384]
http://www.w3.org/2001/04/xmldsig-more#hmac-sha512

SHA-512 [SHA-512] can also be used in HMAC as described describe in section
2.2.1 above. above for HMAC-MD5.

2.3 SignatureMethod Public Key Signature Algorithms

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2.3 Signature Algorithms

2.3.1 RSA-MD5

Identifier:
http://sig.xmldsig.ietf.arpa#rsa-md5
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

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. NOT RECOMMENDED.

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2.3.2 RSA-SHA-256 RSA-SHA256

Identifier:
http://sig.xmldsig.ietf.arpa#rsa-sha256
http://www.w3.org/2001/04/xmldsig-more#rsa-sha256

An example of use is

[I think the SHA-256/384/512 RSA signature algorithms should use
PKCS#1 v2, i.e., OAEP.]

2.3.3 RSA-SHA-512 RSA-SHA384

Identifier:
http://sig.xmldsig.ietf.arpa#rsa-sha512
http://www.w3.org/2001/04/xmldsig-more#rsa-sha384

An example of use is

2.3.4 RSA-SHA-384 RSA-SHA512

Identifier:
http://sig.xmldsig.ietf.arpa#rsa-sha384
http://www.w3.org/2001/04/xmldsig-more#rsa-sha512

An example of use is

2.4 Canonicalizaton CanonicalizatonMethod Algorithms

2.4.1 Minimal Canonicalization

At this time there are not two independent interoperable implementations of Minimal Canonicalization.
Canonicalization have not been announced. Therefore, when XML

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Digital Siganture is advanced from Proposed Standard to Draft
Standard, it must be dropped from the standard track documents.
However, there is still substantial interest and indicates of possible future use
for Minimal Canonicalization which can be found
in Canonicalization. For its definition, see [RFC 3075],
Section 6.5.1.

For reference, it's identifier is: remains:
http://www.w3.org/2000/09/xmldsig#minimal

2.5 Transform Algorithms

Note that all CanonicalizationMethod algorithms listed 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 [RFC 3092]:

<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:

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 3075] for
a same-document XPointer.

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http://www.w3.org/2000/09/xmldsig#minimal

2.5 Transform Algorithms

None included at present.

(Java?)

3. KeyInfo Elements

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. The
PKCS7signedData element is defined to accomodate such structures
within KeyInfo. The binary PKCS #7 strucuture is base64 encoded.
Any signer information present is ignored. The following is a
example, elliding the base64 data [RFC 3092]:

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

4. IANA Considerations

TBD.

None. (so far)

5. Security Considerations

TBD.

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.

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References

[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.

[RC 2045]

[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.

[RFC 3075] - "XML-Signature Syntax and Processing", D. Eastlake, J.
Reagle, D. Solo, March 2001. <http://www.w3.org/TR/2000/CR-
xmldsig-core-20001031>

[RFC 3076] - "Canonical XML Version 1.0", J. Boyer, March 2001.
<http://www.w3.org/TR/2001/REC-xml-c14n-20010315>

[RFC 3092] - "Etymology of 'Foo'", D. Eastlake 3rd, C. Manros, E.
Raymond, 1 April 2001.

[SHA-256] -

[SHA-384] -

[SHA-512] -

Authors Addresses

[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>

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Author's Address

Donald E. Eastlake 3rd
Motorola
155 Beaver Street
Milford, MA 01757 USA

Telephone: +1-508-634-2066 (h)
+1-508-261-5434 (w)
FAX: +1-508-261-4447 (w)
EMail: Donald.Eastlake@motorola.com

Expiration and File Name

This draft expires October 2001.

Its file name is draft-eastlake-xmldsig-uri-01.txt.

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Full Copyright Statement

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
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developing Internet standards in which case the procedures for
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followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS 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.

Expiration and File Name

This draft expires October 2001.

Its file name is draft-eastlake-xmldsig-uri-00.txt.

D. Eastlake 3rd [Page 10] 13]

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