attached is the patch for gnupg2 to ensure that gnupg2 treats empty key flags subpackets as "no standard usages permitted" instead of "all standard usages permitted".
Regards
--dkg
commit 8f8f3984e82a025cf1384132a419f67f39c7e07d
Author: Werner Koch <w...@gnupg.org>
Date: Fri Mar 15 15:46:03 2013 +0100
gpg: Distinguish between missing and cleared key flags.
* include/cipher.h (PUBKEY_USAGE_NONE): New.
* g10/getkey.c (parse_key_usage): Set new flag.
--
We do not want to use the default capabilities (derived from the
algorithm) if any key flags are given in a signature. Thus if key
flags are used in any way, the default key capabilities are never
used.
This allows to create a key with key flags set to all zero so it can't
be used. This better reflects common sense.
Modified g10/getkey.c
--- a/g10/getkey.c
+++ b/g10/getkey.c
@@ -1553,13 +1553,19 @@
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;
}
--- a/include/cipher.h
+++ b/include/cipher.h
@@ -65,6 +65,11 @@
#define PUBKEY_USAGE_CERT GCRY_PK_USAGE_CERT /* Also good to certify keys. */
#define PUBKEY_USAGE_AUTH GCRY_PK_USAGE_AUTH /* Good for authentication. */
#define PUBKEY_USAGE_UNKNOWN GCRY_PK_USAGE_UNKN /* Unknown usage flag. */
+#define PUBKEY_USAGE_NONE 256 /* No usage given. */
+#if (GCRY_PK_USAGE_SIGN | GCRY_PK_USAGE_ENCR | GCRY_PK_USAGE_CERT \
+ | GCRY_PK_USAGE_AUTH | GCRY_PK_USAGE_UNKN) >= 256
+# error Please choose another value for PUBKEY_USAGE_NONE
+#endif
#define DIGEST_ALGO_MD5 /* 1 */ GCRY_MD_MD5
#define DIGEST_ALGO_SHA1 /* 2 */ GCRY_MD_SHA1
signature.asc
Description: OpenPGP digital signature
