Allow to choose algorithms when creating metadata

Signature and digest algorithms can now be selected with the following
command line arguments

  -S <sign alg>   (default: http://www.w3.org/2000/09/xmldsig#rsa-sha1)
  -D <digest alg> (default: http://www.w3.org/2000/09/xmldsig#sha1)

Example:

  $ ../../tools/make_metadata.py \
    -s -x /usr/bin/xmlsec1 \
    -k pki/mykey.pem -c pki/mycert.pem \
    -S http://www.w3.org/2001/04/xmldsig-more#rsa-sha384 \
    -D http://www.w3.org/2001/04/xmlenc#sha512 \
    sp_conf

tools/make_metadata.py

@@ -34,6 +34,12 @@
                     help="xmlsec binaries to be used for the signing")
 parser.add_argument('-w', dest='wellknown',
                     help="Use wellknown namespace prefixes")
+parser.add_argument('-S', dest='signalg',
+                    default='http://www.w3.org/2000/09/xmldsig#rsa-sha1',
+                    help="Algorithm to sign the metadata")
+parser.add_argument('-D', dest='digestalg',
+                    default='http://www.w3.org/2000/09/xmldsig#sha1',
+                    help="Algorithm to compute the digest of the metadata")
 parser.add_argument(dest="config", nargs="+")
 args = parser.parse_args()
 
@@ -76,7 +82,10 @@
         if args.sign:
             assert conf.key_file
             assert conf.cert_file
-            eid, xmldoc = sign_entity_descriptor(eid, args.id, secc)
+            sign_alg = args.signalg
+            digest_alg = args.digestalg
+            eid, xmldoc = sign_entity_descriptor(eid, args.id, secc, sign_alg,
+                                                 digest_alg)
         else:
             xmldoc = None