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gpg: Allow decryption using several passphrases in may cases.

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* g10/mainproc.c (symkey_decrypt_seskey): Check for a valid algorithm.
(proc_symkey_enc): Clear passpharse on error from above function.
--

This does not work reliable as stated in bug 3795 but we can try to
fix ~95% of all cases.  The real fix is to use AEAD which will come
with 2.3

GnuPG-bug-id: 3795, 4050
Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2018-07-06 08:24:57 +02:00
parent 833738a316
commit b4599a0449
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
1 changed files with 15 additions and 0 deletions
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15
g10/mainproc.c
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@ -271,6 +271,14 @@ symkey_decrypt_seskey (DEK *dek, byte *seskey, size_t slen)
gcry_cipher_decrypt ( hd, seskey, slen, NULL, 0 );
gcry_cipher_close ( hd );
/* Here we can only test whether the algo given in decrypted
* session key is a valid OpenPGP algo. With 11 defined
* symmetric algorithms we will miss 4.3% of wrong passphrases
* here. The actual checking is done later during bulk
* decryption; we can't bring this check forward easily. */
if (openpgp_cipher_test_algo (seskey[0]))
return gpg_error (GPG_ERR_BAD_KEY);
/* Now we replace the dek components with the real session key to
decrypt the contents of the sequencing packet. */
@ -353,6 +361,13 @@ proc_symkey_enc (CTX c, PACKET *pkt)
if (symkey_decrypt_seskey (c->dek,
enc->seskey, enc->seskeylen))
{
if (c->dek->s2k_cacheid[0])
{
if (opt.debug)
log_debug ("cleared passphrase cached with ID:"
" %s\n", c->dek->s2k_cacheid);
passphrase_clear_cache (c->dek->s2k_cacheid);
}
xfree (c->dek);
c->dek = NULL;
}