/* We try very hard to use a MDC */
static int
use_mdc(PK_LIST pk_list,int algo)
{
/* RFC-2440 don't has MDC */
if (RFC2440)
return 0;
/* --force-mdc overrides --disable-mdc */
if(opt.force_mdc)
return 1;
if(opt.disable_mdc)
return 0;
/* Do the keys really support MDC? */
if(select_mdc_from_pklist(pk_list))
return 1;
/* The keys don't support MDC, so now we do a bit of a hack - if any
of the AESes or TWOFISH are in the prefs, we assume that the user
can handle a MDC. This is valid for PGP 7, which can handle MDCs
though it will not generate them. 2440bis allows this, by the
way. */
if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
CIPHER_ALGO_AES,NULL)==CIPHER_ALGO_AES)
return 1;
if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
CIPHER_ALGO_AES192,NULL)==CIPHER_ALGO_AES192)
return 1;
if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
CIPHER_ALGO_AES256,NULL)==CIPHER_ALGO_AES256)
return 1;
if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
CIPHER_ALGO_TWOFISH,NULL)==CIPHER_ALGO_TWOFISH)
return 1;
/* Last try. Use MDC for the modern ciphers. */
if (openpgp_cipher_get_algo_blklen (algo) != 8)
return 1;
if (opt.verbose)
warn_missing_mdc_from_pklist (pk_list);
return 0; /* No MDC */
}
/* Return the AEAD algo if we shall use AEAD mode. Returns 0 if AEAD
* shall not be used. */
aead_algo_t
use_aead (pk_list_t pk_list, int algo)
{
int can_use;
if (!opt.flags.rfc4880bis)
{
if (opt.force_aead)
log_info ("Warning: Option %s currently requires option '%s'\n",
"--force-aead", "--rfc4880bis");
return 0;
}
can_use = openpgp_cipher_get_algo_blklen (algo) == 16;
/* With --force-aead we want AEAD. */
if (opt.force_aead)
{
if (!can_use)
{
log_info ("Warning: request to use AEAD ignored for cipher '%s'\n",
openpgp_cipher_algo_name (algo));
return 0;
}
return default_aead_algo ();
}
/* AEAD does only work with 128 bit cipher blocklength. */
if (!can_use)
return 0;
/* Note the user which keys have no AEAD feature flag set. */
if (opt.verbose)
warn_missing_aead_from_pklist (pk_list);
/* If all keys support AEAD we can use it. */
return select_aead_from_pklist (pk_list);
}
/****************
* Decrypt the data, specified by ED with the key DEK.
*/
int
decrypt_data( void *procctx, PKT_encrypted *ed, DEK *dek )
{
decode_filter_ctx_t dfx;
byte *p;
int rc=0, c, i;
byte temp[32];
unsigned blocksize;
unsigned nprefix;
dfx = xtrycalloc (1, sizeof *dfx);
if (!dfx)
return gpg_error_from_syserror ();
dfx->refcount = 1;
if ( opt.verbose && !dek->algo_info_printed )
{
if (!openpgp_cipher_test_algo (dek->algo))
log_info (_("%s encrypted data\n"),
openpgp_cipher_algo_name (dek->algo));
else
log_info (_("encrypted with unknown algorithm %d\n"), dek->algo );
dek->algo_info_printed = 1;
}
rc = openpgp_cipher_test_algo (dek->algo);
if (rc)
goto leave;
blocksize = openpgp_cipher_get_algo_blklen (dek->algo);
if ( !blocksize || blocksize > 16 )
log_fatal ("unsupported blocksize %u\n", blocksize );
nprefix = blocksize;
if ( ed->len && ed->len < (nprefix+2) )
BUG();
if ( ed->mdc_method )
{
if (gcry_md_open (&dfx->mdc_hash, ed->mdc_method, 0 ))
BUG ();
if ( DBG_HASHING )
gcry_md_start_debug (dfx->mdc_hash, "checkmdc");
}
rc = openpgp_cipher_open (&dfx->cipher_hd, dek->algo,
GCRY_CIPHER_MODE_CFB,
(GCRY_CIPHER_SECURE
| ((ed->mdc_method || dek->algo >= 100)?
0 : GCRY_CIPHER_ENABLE_SYNC)));
if (rc)
{
/* We should never get an error here cause we already checked
* that the algorithm is available. */
BUG();
}
/* log_hexdump( "thekey", dek->key, dek->keylen );*/
rc = gcry_cipher_setkey (dfx->cipher_hd, dek->key, dek->keylen);
if ( gpg_err_code (rc) == GPG_ERR_WEAK_KEY )
{
log_info(_("WARNING: message was encrypted with"
" a weak key in the symmetric cipher.\n"));
rc=0;
}
else if( rc )
{
log_error("key setup failed: %s\n", g10_errstr(rc) );
goto leave;
}
if (!ed->buf)
{
log_error(_("problem handling encrypted packet\n"));
goto leave;
}
gcry_cipher_setiv (dfx->cipher_hd, NULL, 0);
if ( ed->len )
{
for (i=0; i < (nprefix+2) && ed->len; i++, ed->len-- )
{
if ( (c=iobuf_get(ed->buf)) == -1 )
break;
else
temp[i] = c;
}
}
else
{
for (i=0; i < (nprefix+2); i++ )
if ( (c=iobuf_get(ed->buf)) == -1 )
break;
else
temp[i] = c;
}
gcry_cipher_decrypt (dfx->cipher_hd, temp, nprefix+2, NULL, 0);
gcry_cipher_sync (dfx->cipher_hd);
p = temp;
/* log_hexdump( "prefix", temp, nprefix+2 ); */
if (dek->symmetric
&& (p[nprefix-2] != p[nprefix] || p[nprefix-1] != p[nprefix+1]) )
{
rc = gpg_error (GPG_ERR_BAD_KEY);
goto leave;
}
if ( dfx->mdc_hash )
gcry_md_write (dfx->mdc_hash, temp, nprefix+2);
dfx->refcount++;
if ( ed->mdc_method )
iobuf_push_filter ( ed->buf, mdc_decode_filter, dfx );
else
iobuf_push_filter ( ed->buf, decode_filter, dfx );
proc_packets ( procctx, ed->buf );
ed->buf = NULL;
if ( ed->mdc_method && dfx->eof_seen == 2 )
rc = gpg_error (GPG_ERR_INV_PACKET);
else if ( ed->mdc_method )
{
/* We used to let parse-packet.c handle the MDC packet but this
turned out to be a problem with compressed packets: With old
style packets there is no length information available and
the decompressor uses an implicit end. However we can't know
this implicit end beforehand (:-) and thus may feed the
decompressor with more bytes than actually needed. It would
be possible to unread the extra bytes but due to our weird
iobuf system any unread is non reliable due to filters
already popped off. The easy and sane solution is to care
about the MDC packet only here and never pass it to the
packet parser. Fortunatley the OpenPGP spec requires a
strict format for the MDC packet so that we know that 22
bytes are appended. */
int datalen = gcry_md_get_algo_dlen (ed->mdc_method);
assert (dfx->cipher_hd);
assert (dfx->mdc_hash);
gcry_cipher_decrypt (dfx->cipher_hd, dfx->defer, 22, NULL, 0);
gcry_md_write (dfx->mdc_hash, dfx->defer, 2);
gcry_md_final (dfx->mdc_hash);
if (dfx->defer[0] != '\xd3' || dfx->defer[1] != '\x14' )
{
log_error("mdc_packet with invalid encoding\n");
rc = gpg_error (GPG_ERR_INV_PACKET);
}
else if (datalen != 20
|| memcmp (gcry_md_read (dfx->mdc_hash, 0),
dfx->defer+2,datalen ))
rc = gpg_error (GPG_ERR_BAD_SIGNATURE);
/* log_printhex("MDC message:", dfx->defer, 22); */
/* log_printhex("MDC calc:", gcry_md_read (dfx->mdc_hash,0), datalen); */
}
leave:
release_dfx_context (dfx);
return rc;
}
static void
write_header (cipher_filter_context_t *cfx, iobuf_t a)
{
gcry_error_t err;
PACKET pkt;
PKT_encrypted ed;
byte temp[18];
unsigned int blocksize;
unsigned int nprefix;
blocksize = openpgp_cipher_get_algo_blklen (cfx->dek->algo);
if ( blocksize < 8 || blocksize > 16 )
log_fatal ("unsupported blocksize %u\n", blocksize);
memset (&ed, 0, sizeof ed);
ed.len = cfx->datalen;
ed.extralen = blocksize + 2;
ed.new_ctb = !ed.len;
if (cfx->dek->use_mdc)
{
ed.mdc_method = DIGEST_ALGO_SHA1;
gcry_md_open (&cfx->mdc_hash, DIGEST_ALGO_SHA1, 0);
if (DBG_HASHING)
gcry_md_debug (cfx->mdc_hash, "creatmdc");
}
else if (!opt.no_mdc_warn)
{
log_info ("WARNING: "
"encrypting without integrity protection is dangerous\n");
}
write_status_printf (STATUS_BEGIN_ENCRYPTION, "%d %d",
ed.mdc_method, cfx->dek->algo);
init_packet (&pkt);
pkt.pkttype = cfx->dek->use_mdc? PKT_ENCRYPTED_MDC : PKT_ENCRYPTED;
pkt.pkt.encrypted = &ed;
if (build_packet( a, &pkt))
log_bug ("build_packet(ENCR_DATA) failed\n");
nprefix = blocksize;
gcry_randomize (temp, nprefix, GCRY_STRONG_RANDOM );
temp[nprefix] = temp[nprefix-2];
temp[nprefix+1] = temp[nprefix-1];
print_cipher_algo_note (cfx->dek->algo);
err = openpgp_cipher_open (&cfx->cipher_hd,
cfx->dek->algo,
GCRY_CIPHER_MODE_CFB,
(GCRY_CIPHER_SECURE
| ((cfx->dek->use_mdc || cfx->dek->algo >= 100)?
0 : GCRY_CIPHER_ENABLE_SYNC)));
if (err)
{
/* We should never get an error here cause we already checked,
* that the algorithm is available. */
BUG();
}
/* log_hexdump ("thekey", cfx->dek->key, cfx->dek->keylen); */
gcry_cipher_setkey (cfx->cipher_hd, cfx->dek->key, cfx->dek->keylen);
gcry_cipher_setiv (cfx->cipher_hd, NULL, 0);
/* log_hexdump ("prefix", temp, nprefix+2); */
if (cfx->mdc_hash) /* Hash the "IV". */
gcry_md_write (cfx->mdc_hash, temp, nprefix+2 );
gcry_cipher_encrypt (cfx->cipher_hd, temp, nprefix+2, NULL, 0);
gcry_cipher_sync (cfx->cipher_hd);
iobuf_write (a, temp, nprefix+2);
cfx->short_blklen_warn = (blocksize < 16);
cfx->short_blklen_count = nprefix+2;
cfx->wrote_header = 1;
}
/****************
* Decrypt the data, specified by ED with the key DEK.
*/
int
decrypt_data (ctrl_t ctrl, void *procctx, PKT_encrypted *ed, DEK *dek)
{
decode_filter_ctx_t dfx;
byte *p;
int rc=0, c, i;
byte temp[32];
unsigned blocksize;
unsigned nprefix;
dfx = xtrycalloc (1, sizeof *dfx);
if (!dfx)
return gpg_error_from_syserror ();
dfx->refcount = 1;
if ( opt.verbose && !dek->algo_info_printed )
{
if (!openpgp_cipher_test_algo (dek->algo))
log_info (_("%s encrypted data\n"),
openpgp_cipher_algo_name (dek->algo));
else
log_info (_("encrypted with unknown algorithm %d\n"), dek->algo );
dek->algo_info_printed = 1;
}
{
char buf[20];
snprintf (buf, sizeof buf, "%d %d", ed->mdc_method, dek->algo);
write_status_text (STATUS_DECRYPTION_INFO, buf);
}
if (opt.show_session_key)
{
char numbuf[25];
char *hexbuf;
snprintf (numbuf, sizeof numbuf, "%d:", dek->algo);
hexbuf = bin2hex (dek->key, dek->keylen, NULL);
if (!hexbuf)
{
rc = gpg_error_from_syserror ();
goto leave;
}
log_info ("session key: '%s%s'\n", numbuf, hexbuf);
write_status_strings (STATUS_SESSION_KEY, numbuf, hexbuf, NULL);
xfree (hexbuf);
}
rc = openpgp_cipher_test_algo (dek->algo);
if (rc)
goto leave;
blocksize = openpgp_cipher_get_algo_blklen (dek->algo);
if ( !blocksize || blocksize > 16 )
log_fatal ("unsupported blocksize %u\n", blocksize );
nprefix = blocksize;
if ( ed->len && ed->len < (nprefix+2) )
{
/* An invalid message. We can't check that during parsing
because we may not know the used cipher then. */
rc = gpg_error (GPG_ERR_INV_PACKET);
goto leave;
}
if ( ed->mdc_method )
{
if (gcry_md_open (&dfx->mdc_hash, ed->mdc_method, 0 ))
BUG ();
if ( DBG_HASHING )
gcry_md_debug (dfx->mdc_hash, "checkmdc");
}
rc = openpgp_cipher_open (&dfx->cipher_hd, dek->algo,
GCRY_CIPHER_MODE_CFB,
(GCRY_CIPHER_SECURE
| ((ed->mdc_method || dek->algo >= 100)?
0 : GCRY_CIPHER_ENABLE_SYNC)));
if (rc)
{
/* We should never get an error here cause we already checked
* that the algorithm is available. */
BUG();
}
/* log_hexdump( "thekey", dek->key, dek->keylen );*/
rc = gcry_cipher_setkey (dfx->cipher_hd, dek->key, dek->keylen);
if ( gpg_err_code (rc) == GPG_ERR_WEAK_KEY )
{
log_info(_("WARNING: message was encrypted with"
" a weak key in the symmetric cipher.\n"));
rc=0;
}
else if( rc )
{
log_error("key setup failed: %s\n", gpg_strerror (rc) );
goto leave;
}
if (!ed->buf)
{
log_error(_("problem handling encrypted packet\n"));
goto leave;
}
gcry_cipher_setiv (dfx->cipher_hd, NULL, 0);
if ( ed->len )
{
for (i=0; i < (nprefix+2) && ed->len; i++, ed->len-- )
{
if ( (c=iobuf_get(ed->buf)) == -1 )
break;
else
temp[i] = c;
}
}
else
{
for (i=0; i < (nprefix+2); i++ )
if ( (c=iobuf_get(ed->buf)) == -1 )
break;
else
temp[i] = c;
}
gcry_cipher_decrypt (dfx->cipher_hd, temp, nprefix+2, NULL, 0);
gcry_cipher_sync (dfx->cipher_hd);
p = temp;
/* log_hexdump( "prefix", temp, nprefix+2 ); */
if (dek->symmetric
&& (p[nprefix-2] != p[nprefix] || p[nprefix-1] != p[nprefix+1]) )
{
rc = gpg_error (GPG_ERR_BAD_KEY);
goto leave;
}
if ( dfx->mdc_hash )
gcry_md_write (dfx->mdc_hash, temp, nprefix+2);
dfx->refcount++;
dfx->partial = ed->is_partial;
dfx->length = ed->len;
if ( ed->mdc_method )
iobuf_push_filter ( ed->buf, mdc_decode_filter, dfx );
else
iobuf_push_filter ( ed->buf, decode_filter, dfx );
if (opt.unwrap_encryption)
{
char *filename;
estream_t fp;
rc = get_output_file ("", 0, ed->buf, &filename, &fp);
if (! rc)
{
iobuf_t output = iobuf_esopen (fp, "w", 0);
armor_filter_context_t *afx = NULL;
if (opt.armor)
{
afx = new_armor_context ();
push_armor_filter (afx, output);
}
iobuf_copy (output, ed->buf);
if ((rc = iobuf_error (ed->buf)))
log_error (_("error reading '%s': %s\n"),
filename, gpg_strerror (rc));
else if ((rc = iobuf_error (output)))
log_error (_("error writing '%s': %s\n"),
filename, gpg_strerror (rc));
iobuf_close (output);
if (afx)
release_armor_context (afx);
}
}
else
proc_packets (ctrl, procctx, ed->buf );
ed->buf = NULL;
if (dfx->eof_seen > 1 )
rc = gpg_error (GPG_ERR_INV_PACKET);
else if ( ed->mdc_method )
{
/* We used to let parse-packet.c handle the MDC packet but this
turned out to be a problem with compressed packets: With old
style packets there is no length information available and
the decompressor uses an implicit end. However we can't know
this implicit end beforehand (:-) and thus may feed the
decompressor with more bytes than actually needed. It would
be possible to unread the extra bytes but due to our weird
iobuf system any unread is non reliable due to filters
already popped off. The easy and sane solution is to care
about the MDC packet only here and never pass it to the
packet parser. Fortunatley the OpenPGP spec requires a
strict format for the MDC packet so that we know that 22
bytes are appended. */
int datalen = gcry_md_get_algo_dlen (ed->mdc_method);
log_assert (dfx->cipher_hd);
log_assert (dfx->mdc_hash);
gcry_cipher_decrypt (dfx->cipher_hd, dfx->defer, 22, NULL, 0);
gcry_md_write (dfx->mdc_hash, dfx->defer, 2);
gcry_md_final (dfx->mdc_hash);
if ( dfx->defer[0] != '\xd3'
|| dfx->defer[1] != '\x14'
|| datalen != 20
|| memcmp (gcry_md_read (dfx->mdc_hash, 0), dfx->defer+2, datalen))
rc = gpg_error (GPG_ERR_BAD_SIGNATURE);
/* log_printhex("MDC message:", dfx->defer, 22); */
/* log_printhex("MDC calc:", gcry_md_read (dfx->mdc_hash,0), datalen); */
}
leave:
release_dfx_context (dfx);
return rc;
}
/****************
* Protect the secret key with the passphrase from DEK
*/
int
protect_secret_key( PKT_secret_key *sk, DEK *dek )
{
int i,j, rc = 0;
byte *buffer;
size_t nbytes;
u16 csum;
if( !dek )
return 0;
if( !sk->is_protected ) { /* okay, apply the protection */
gcry_cipher_hd_t cipher_hd=NULL;
if ( openpgp_cipher_test_algo ( sk->protect.algo ) ) {
/* Unsupport protection algorithm. */
rc = gpg_error (GPG_ERR_CIPHER_ALGO);
}
else {
print_cipher_algo_note( sk->protect.algo );
if ( openpgp_cipher_open (&cipher_hd, sk->protect.algo,
GCRY_CIPHER_MODE_CFB,
(GCRY_CIPHER_SECURE
| (sk->protect.algo >= 100 ?
0 : GCRY_CIPHER_ENABLE_SYNC))) )
BUG();
if ( gcry_cipher_setkey ( cipher_hd, dek->key, dek->keylen ) )
log_info(_("WARNING: Weak key detected"
" - please change passphrase again.\n"));
sk->protect.ivlen = openpgp_cipher_get_algo_blklen (sk->protect.algo);
assert( sk->protect.ivlen <= DIM(sk->protect.iv) );
if( sk->protect.ivlen != 8 && sk->protect.ivlen != 16 )
BUG(); /* yes, we are very careful */
gcry_create_nonce (sk->protect.iv, sk->protect.ivlen);
gcry_cipher_setiv (cipher_hd, sk->protect.iv, sk->protect.ivlen);
if( sk->version >= 4 ) {
byte *bufarr[PUBKEY_MAX_NSKEY];
size_t narr[PUBKEY_MAX_NSKEY];
unsigned int nbits[PUBKEY_MAX_NSKEY];
int ndata=0;
byte *p, *data;
for (j=0, i = pubkey_get_npkey(sk->pubkey_algo);
i < pubkey_get_nskey(sk->pubkey_algo); i++, j++ )
{
assert (!gcry_mpi_get_flag (sk->skey[i],
GCRYMPI_FLAG_OPAQUE));
if (gcry_mpi_aprint (GCRYMPI_FMT_USG, bufarr+j,
narr+j, sk->skey[i]))
BUG();
nbits[j] = gcry_mpi_get_nbits (sk->skey[i]);
ndata += narr[j] + 2;
}
for ( ; j < PUBKEY_MAX_NSKEY; j++ )
bufarr[j] = NULL;
ndata += opt.simple_sk_checksum? 2 : 20; /* for checksum */
data = xmalloc_secure( ndata );
p = data;
for(j=0; j < PUBKEY_MAX_NSKEY && bufarr[j]; j++ ) {
p[0] = nbits[j] >> 8 ;
p[1] = nbits[j];
p += 2;
memcpy(p, bufarr[j], narr[j] );
p += narr[j];
xfree(bufarr[j]);
}
if (opt.simple_sk_checksum) {
log_info (_("generating the deprecated 16-bit checksum"
" for secret key protection\n"));
csum = checksum( data, ndata-2);
sk->csum = csum;
*p++ = csum >> 8;
*p++ = csum;
sk->protect.sha1chk = 0;
}
else {