diff -Naurp gnupg-1.4.12/g10/getkey.c gnupg-1.4.12.oden/g10/getkey.c
--- gnupg-1.4.12/g10/getkey.c	2012-01-20 05:51:15.000000000 -0500
+++ gnupg-1.4.12.oden/g10/getkey.c	2013-10-09 11:15:12.000000000 -0400
@@ -1494,13 +1494,19 @@ parse_key_usage(PKT_signature *sig)
 
       if(flags)
 	key_usage |= PUBKEY_USAGE_UNKNOWN;
+
+      if (!key_usage)
+	key_usage |= PUBKEY_USAGE_NONE;
     }
+  else if (p) /* Key flags of length zero.  */
+    key_usage |= PUBKEY_USAGE_NONE;
 
   /* We set PUBKEY_USAGE_UNKNOWN to indicate that this key has a
      capability that we do not handle.  This serves to distinguish
      between a zero key usage which we handle as the default
      capabilities for that algorithm, and a usage that we do not
-     handle. */
+     handle.  Likewise we use PUBKEY_USAGE_NONE to indicate that
+     key_flags have been given but they do not specify any usage.  */
 
   return key_usage;
 }
diff -Naurp gnupg-1.4.12/g10/keygen.c gnupg-1.4.12.oden/g10/keygen.c
--- gnupg-1.4.12/g10/keygen.c	2012-01-20 05:51:15.000000000 -0500
+++ gnupg-1.4.12.oden/g10/keygen.c	2013-10-09 11:15:12.000000000 -0400
@@ -210,9 +210,6 @@ do_add_key_flags (PKT_signature *sig, un
     if (use & PUBKEY_USAGE_AUTH)
         buf[0] |= 0x20;
 
-    if (!buf[0])
-        return;
-
     build_sig_subpkt (sig, SIGSUBPKT_KEY_FLAGS, buf, 1);
 }
 
diff -Naurp gnupg-1.4.12/include/cipher.h gnupg-1.4.12.oden/include/cipher.h
--- gnupg-1.4.12/include/cipher.h	2012-01-20 05:51:16.000000000 -0500
+++ gnupg-1.4.12.oden/include/cipher.h	2013-10-09 11:15:12.000000000 -0400
@@ -57,6 +57,7 @@
 #define PUBKEY_USAGE_CERT    4      /* key is also good to certify other keys*/
 #define PUBKEY_USAGE_AUTH    8      /* key is good for authentication */
 #define PUBKEY_USAGE_UNKNOWN 128    /* key has an unknown usage bit */
+#define PUBKEY_USAGE_NONE    256    /* No usage given. */
 
 #define DIGEST_ALGO_MD5       1
 #define DIGEST_ALGO_SHA1      2