update: support other hashing algorithms than SHA-1

src/misc/update_crypto.c

@@ -285,9 +285,6 @@ static int parse_signature_packet( signature_packet_t *p_sig,
     if( p_sig->public_key_algo != GCRY_PK_DSA )
         goto error;
 
-    if( p_sig->digest_algo != GCRY_MD_SHA1 )
-        goto error;
-
     switch( p_sig->type )
     {
         case BINARY_SIGNATURE:
@@ -454,6 +451,10 @@ int verify_signature( signature_packet_t *sign, public_key_packet_t *p_key,
         goto problem;
 
     int i_hash_len = gcry_md_get_algo_dlen (sign->digest_algo);
+    if (sign->public_key_algo == GCRY_PK_DSA) {
+        if (i_hash_len > 20)
+            i_hash_len = 20;
+    }
     if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
         gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
         goto problem;