Hola, la dll, que uso me define estos parametros, no seran buenos verdad.
Código:
public static DigestMethod SHA1 = new DigestMethod("SHA1", "http://www.w3.org/2000/09/xmldsig#sha1", "1.3.14.3.2.26");
public static DigestMethod SHA256 = new DigestMethod("SHA256", "http://www.w3.org/2001/04/xmlenc#sha256", "2.16.840.1.101.3.4.2.1");
public static DigestMethod SHA512 = new DigestMethod("SHA512", "http://www.w3.org/2001/04/xmlenc#sha512", "2.16.840.1.101.3.4.2.3");