/*
* Write a pubkey-enc packet for the public key PK to OUT.
*/
int
write_pubkey_enc (ctrl_t ctrl,
PKT_public_key *pk, int throw_keyid, DEK *dek, iobuf_t out)
{
PACKET pkt;
PKT_pubkey_enc *enc;
int rc;
gcry_mpi_t frame;
print_pubkey_algo_note ( pk->pubkey_algo );
enc = xmalloc_clear ( sizeof *enc );
enc->pubkey_algo = pk->pubkey_algo;
keyid_from_pk( pk, enc->keyid );
enc->throw_keyid = throw_keyid;
/* Okay, what's going on: We have the session key somewhere in
* the structure DEK and want to encode this session key in an
* integer value of n bits. pubkey_nbits gives us the number of
* bits we have to use. We then encode the session key in some
* way and we get it back in the big intger value FRAME. Then
* we use FRAME, the public key PK->PKEY and the algorithm
* number PK->PUBKEY_ALGO and pass it to pubkey_encrypt which
* returns the encrypted value in the array ENC->DATA. This
* array has a size which depends on the used algorithm (e.g. 2
* for Elgamal). We don't need frame anymore because we have
* everything now in enc->data which is the passed to
* build_packet(). */
frame = encode_session_key (pk->pubkey_algo, dek,
pubkey_nbits (pk->pubkey_algo, pk->pkey));
rc = pk_encrypt (pk->pubkey_algo, enc->data, frame, pk, pk->pkey);
gcry_mpi_release (frame);
if (rc)
log_error ("pubkey_encrypt failed: %s\n", gpg_strerror (rc) );
else
{
if ( opt.verbose )
{
char *ustr = get_user_id_string_native (ctrl, enc->keyid);
log_info (_("%s/%s.%s encrypted for: \"%s\"\n"),
openpgp_pk_algo_name (enc->pubkey_algo),
openpgp_cipher_algo_name (dek->algo),
dek->use_aead? openpgp_aead_algo_name (dek->use_aead)
/**/ : "CFB",
ustr );
xfree (ustr);
}
/* And write it. */
init_packet (&pkt);
pkt.pkttype = PKT_PUBKEY_ENC;
pkt.pkt.pubkey_enc = enc;
rc = build_packet (out, &pkt);
if (rc)
log_error ("build_packet(pubkey_enc) failed: %s\n",
gpg_strerror (rc));
}
free_pubkey_enc(enc);
return rc;
}
/* Encrypt the DEK under the key contained in CERT and return it as a
canonical S-Exp in encval. */
static int
encrypt_dek (const DEK dek, ksba_cert_t cert, unsigned char **encval)
{
gcry_sexp_t s_ciph, s_data, s_pkey;
int rc;
ksba_sexp_t buf;
size_t len;
*encval = NULL;
/* get the key from the cert */
buf = ksba_cert_get_public_key (cert);
if (!buf)
{
log_error ("no public key for recipient\n");
return gpg_error (GPG_ERR_NO_PUBKEY);
}
len = gcry_sexp_canon_len (buf, 0, NULL, NULL);
if (!len)
{
log_error ("libksba did not return a proper S-Exp\n");
return gpg_error (GPG_ERR_BUG);
}
rc = gcry_sexp_sscan (&s_pkey, NULL, (char*)buf, len);
xfree (buf); buf = NULL;
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
return rc;
}
/* Put the encoded cleartext into a simple list. */
s_data = NULL; /* (avoid compiler warning) */
rc = encode_session_key (dek, &s_data);
if (rc)
{
log_error ("encode_session_key failed: %s\n", gpg_strerror (rc));
return rc;
}
/* pass it to libgcrypt */
rc = gcry_pk_encrypt (&s_ciph, s_data, s_pkey);
gcry_sexp_release (s_data);
gcry_sexp_release (s_pkey);
/* Reformat it. */
if (!rc)
{
rc = make_canon_sexp (s_ciph, encval, NULL);
gcry_sexp_release (s_ciph);
}
return rc;
}
/****************
* Write pubkey-enc packets from the list of PKs to OUT.
*/
static int
write_pubkey_enc_from_list( PK_LIST pk_list, DEK *dek, IOBUF out )
{
PACKET pkt;
PKT_public_key *pk;
PKT_pubkey_enc *enc;
int rc;
for( ; pk_list; pk_list = pk_list->next ) {
MPI frame;
pk = pk_list->pk;
print_pubkey_algo_note( pk->pubkey_algo );
enc = xmalloc_clear( sizeof *enc );
enc->pubkey_algo = pk->pubkey_algo;
keyid_from_pk( pk, enc->keyid );
enc->throw_keyid = (opt.throw_keyid || (pk_list->flags&1));
if(opt.throw_keyid && (PGP2 || PGP6 || PGP7 || PGP8))
{
log_info(_("you may not use %s while in %s mode\n"),
"--throw-keyid",compliance_option_string());
compliance_failure();
}
/* Okay, what's going on: We have the session key somewhere in
* the structure DEK and want to encode this session key in
* an integer value of n bits. pubkey_nbits gives us the
* number of bits we have to use. We then encode the session
* key in some way and we get it back in the big intger value
* FRAME. Then we use FRAME, the public key PK->PKEY and the
* algorithm number PK->PUBKEY_ALGO and pass it to pubkey_encrypt
* which returns the encrypted value in the array ENC->DATA.
* This array has a size which depends on the used algorithm
* (e.g. 2 for Elgamal). We don't need frame anymore because we
* have everything now in enc->data which is the passed to
* build_packet()
*/
frame = encode_session_key( dek, pubkey_nbits( pk->pubkey_algo,
pk->pkey ) );
rc = pubkey_encrypt( pk->pubkey_algo, enc->data, frame, pk->pkey );
mpi_free( frame );
if( rc )
log_error("pubkey_encrypt failed: %s\n", g10_errstr(rc) );
else {
if( opt.verbose ) {
char *ustr = get_user_id_string_native (enc->keyid);
log_info(_("%s/%s encrypted for: \"%s\"\n"),
pubkey_algo_to_string(enc->pubkey_algo),
cipher_algo_to_string(dek->algo), ustr );
xfree(ustr);
}
/* and write it */
init_packet(&pkt);
pkt.pkttype = PKT_PUBKEY_ENC;
pkt.pkt.pubkey_enc = enc;
rc = build_packet( out, &pkt );
if( rc )
log_error("build_packet(pubkey_enc) failed: %s\n", g10_errstr(rc));
}
free_pubkey_enc(enc);
if( rc )
return rc;
}
return 0;
}