6.4.1 DSA
- Identifier:
- http://www.w3.org/2000/09/xmldsig#dsa-sha1
The DSA algorithm [DSS] takes no explicit
parameters. An example of a DSA SignatureMethod element is:
<SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"/>
The output of the DSA algorithm consists of a pair of integers usually
referred by the pair (r, s). The signature value consists of the base64
encoding of the concatenation of two octet-streams that respectively result
from the octet-encoding of the values r and s in that order.
Integer to octet-stream
conversion must be done according to the I2OSP operation defined in the RFC 2437 [PKCS1] specification with a l parameter
equal to 20. For example, the SignatureValue element for a DSA signature
(r, s) with values specified in hexadecimal:
r = 8BAC1AB6 6410435C B7181F95 B16AB97C 92B341C0s = 41E2345F 1F56DF24 58F426D1 55B4BA2D B6DCD8C8
from the example in Appendix 5 of the DSS standard would be
<SignatureValue>i6watmQQQ1y3GB+VsWq5fJKzQcBB4jRfH1bfJFj0JtFVtLotttzYyA==</SignatureValue>