Signature algorithm identifiers appear as the Algorithm attribute of SignatureMethod elements, as shown in Figure 18-3. They take two implicit parameters: their keying material and the octet stream output by CanonicalizationMethod. MAC and signature algorithms are syntactically identical, but a signature implies public key cryptography.
DSA Identifier: http://www.w3.org/2000/09/xmldsig#dsa-sha1
The DSA algorithm [DSS] is mandatory to implement for XML Digital Signature applications. It takes no explicit parameters. An example of a DSA SignatureMethod element follows:
The output of the DSA algorithm is a pair of integers usually ...