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gpg: Disable an MD5 workaround for pgp2 by default.

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* g10/sig-check.c (do_check): Move some code to ...
* g10/misc.c (print_md5_rejected_note): new function.
* g10/mainproc.c (proc_tree, proc_plaintext): Enable MD5 workaround
only if option --allow-weak-digest-algos is used.
This commit is contained in:
Werner Koch 2014-08-12 10:36:30 +02:00
parent 2b8d8369d5
commit ae29b52119
4 changed files with 32 additions and 22 deletions
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1
g10/main.h
View File

@ -74,6 +74,7 @@ extern int g10_errors_seen;
void print_pubkey_algo_note (pubkey_algo_t algo);
void print_cipher_algo_note (cipher_algo_t algo);
void print_digest_algo_note (digest_algo_t algo);
void print_md5_rejected_note (void);
/*-- armor.c --*/
char *make_radix64_string( const byte *data, size_t len );

27
g10/mainproc.c
View File

@ -694,7 +694,8 @@ proc_plaintext( CTX c, PACKET *pkt )
gcry_md_enable( c->mfx.md, DIGEST_ALGO_SHA1 );
gcry_md_enable( c->mfx.md, DIGEST_ALGO_MD5 );
}
if( opt.pgp2_workarounds && only_md5 && !opt.skip_verify ) {
if (opt.pgp2_workarounds && only_md5 && !opt.skip_verify
&& opt.flags.allow_weak_digest_algos) {
/* This is a kludge to work around a bug in pgp2. It does only
* catch those mails which are armored. To catch the non-armored
* pgp mails we could see whether there is the signature packet
@ -2132,7 +2133,8 @@ proc_tree( CTX c, KBNODE node )
if( !opt.pgp2_workarounds )
;
else if( sig->digest_algo == DIGEST_ALGO_MD5
&& is_RSA( sig->pubkey_algo ) ) {
&& is_RSA( sig->pubkey_algo)
&& opt.flags.allow_weak_digest_algos) {
/* enable a workaround for a pgp2 bug */
if (gcry_md_open (&c->mfx.md2, DIGEST_ALGO_MD5, 0))
BUG ();
@ -2145,16 +2147,17 @@ proc_tree( CTX c, KBNODE node )
if (gcry_md_open (&c->mfx.md2, sig->digest_algo, 0 ))
BUG ();
}
#if 0 /* workaround disabled */
/* Here we have another hack to work around a pgp 2 bug
* It works by not using the textmode for detached signatures;
* this will let the first signature check (on md) fail
* but the second one (on md2) which adds an extra CR should
* then produce the "correct" hash. This is very, very ugly
* hack but it may help in some cases (and break others)
*/
/* c->mfx.md2? 0 :(sig->sig_class == 0x01) */
#endif
/* Here we used to have another hack to work around a pgp
* 2 bug: It worked by not using the textmode for detached
* signatures; this would let the first signature check
* (on md) fail but the second one (on md2), which adds an
* extra CR would then have produced the "correct" hash.
* This is very, very ugly hack but it may haved help in
* some cases (and break others).
* c->mfx.md2? 0 :(sig->sig_class == 0x01)
*/
if ( DBG_HASHING ) {
gcry_md_debug( c->mfx.md, "verify" );
if ( c->mfx.md2 )

15
g10/misc.c
View File

@ -342,6 +342,21 @@ print_digest_algo_note (digest_algo_t algo)
}
void
print_md5_rejected_note (void)
{
static int shown;
if (!shown)
{
log_info
(_("Note: signatures using the %s algorithm are rejected\n"),
"MD5");
shown = 1;
}
}
/* Map OpenPGP algo numbers to those used by Libgcrypt. We need to do
this for algorithms we implemented in Libgcrypt after they become
part of OpenPGP. */

11
g10/sig-check.c
View File

@ -269,16 +269,7 @@ do_check( PKT_public_key *pk, PKT_signature *sig, gcry_md_hd_t digest,
if (sig->digest_algo == GCRY_MD_MD5
&& !opt.flags.allow_weak_digest_algos)
{
static int shown;
if (!shown)
{
log_info
(_("Note: signatures using the %s algorithm are rejected\n"),
"MD5");
shown = 1;
}
print_md5_rejected_note ();
return GPG_ERR_DIGEST_ALGO;
}