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gpg: Implement AEAD for SKESK packets.
* g10/packet.h (PKT_symkey_enc): Add field aead_algo. * g10/build-packet.c (do_symkey_enc): Support version 5 packets. * g10/parse-packet.c (parse_symkeyenc): Ditto. * g10/encrypt.c (encrypt_symmetric): Force using a random session key in AEAD mode. (encrypt_seskey): Add and support arg aead_algo. (write_symkey_enc): Ditto. (encrypt_simple): Adjust accordingly. (encrypt_filter): Ditto. * g10/gpgcompose.c (sk_esk): For now call encrypt_seskey without AEAD support. * g10/mainproc.c (symkey_decrypt_seskey): Support AEAD. Nver call BUG but return an error. (proc_symkey_enc): Call symkey_decrypt_seskey in a bug compatible way. * g10/import.c (check_prefs): Check AEAD preferences. * g10/keyedit.c (show_prefs): Print AEAD preferences. -- For easier debugging this patch also changes some diagnostics to also print the encryption mode with the cipher algorithm. Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch
parent
da3015e3c0
commit
9aab9167bc
11 changed files with 300 additions and 104 deletions
151
g10/encrypt.c
151
g10/encrypt.c
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@ -47,12 +47,12 @@ static int write_pubkey_enc_from_list (ctrl_t ctrl,
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/****************
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* Encrypt FILENAME with only the symmetric cipher. Take input from
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* stdin if FILENAME is NULL.
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* stdin if FILENAME is NULL. If --force-aead is used we use an SKESK.
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*/
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int
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encrypt_symmetric (const char *filename)
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{
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return encrypt_simple( filename, 1, 0 );
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return encrypt_simple( filename, 1, opt.force_aead);
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}
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@ -70,14 +70,16 @@ encrypt_store (const char *filename)
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/* Encrypt a session key using DEK and store a pointer to the result
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* at R_ENCKEY and its length at R_ENCKEYLEN.
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*
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* R_SESKEY points to the unencrypted session key (.KEY, >KEYLEN) and
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* R_SESKEY points to the unencrypted session key (.KEY, .KEYLEN) and
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* the algorithm that will be used to encrypt the contents of the
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* SKESK packet (.ALGO). If R_SESKEY points to NULL, then a random
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* session key that is appropriate for DEK->ALGO is generated and
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* stored at R_SESKEY.
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* stored at R_SESKEY. If AEAD_ALGO is not 0 the given AEAD algorithm
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* is used for encryption.
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*/
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gpg_error_t
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encrypt_seskey (DEK *dek, DEK **r_seskey, void **r_enckey, size_t *r_enckeylen)
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encrypt_seskey (DEK *dek, aead_algo_t aead_algo,
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DEK **r_seskey, void **r_enckey, size_t *r_enckeylen)
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{
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gpg_error_t err;
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gcry_cipher_hd_t hd = NULL;
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@ -102,30 +104,84 @@ encrypt_seskey (DEK *dek, DEK **r_seskey, void **r_enckey, size_t *r_enckeylen)
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/*log_hexdump( "thekey", c->key, c->keylen );*/
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}
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buf = xtrymalloc_secure (1 + seskey->keylen);
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if (!buf)
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if (aead_algo)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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unsigned int noncelen;
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enum gcry_cipher_modes ciphermode;
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byte ad[4];
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err = openpgp_aead_algo_info (aead_algo, &ciphermode, &noncelen);
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if (err)
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goto leave;
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/* Allocate space for the nonce, the key, and the authentication
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* tag (16). */
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buf = xtrymalloc_secure (noncelen + seskey->keylen + 16);
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if (!buf)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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gcry_randomize (buf, noncelen, GCRY_STRONG_RANDOM);
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err = openpgp_cipher_open (&hd, dek->algo,
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ciphermode, GCRY_CIPHER_SECURE);
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if (!err)
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err = gcry_cipher_setkey (hd, dek->key, dek->keylen);
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if (!err)
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err = gcry_cipher_setiv (hd, buf, noncelen);
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if (err)
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goto leave;
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ad[0] = (0xc0 | PKT_SYMKEY_ENC);
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ad[1] = 5;
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ad[2] = dek->algo;
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ad[3] = aead_algo;
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err = gcry_cipher_authenticate (hd, ad, 4);
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if (err)
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goto leave;
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memcpy (buf + noncelen, seskey->key, seskey->keylen);
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gcry_cipher_final (hd);
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err = gcry_cipher_encrypt (hd, buf + noncelen, seskey->keylen, NULL,0);
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if (err)
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goto leave;
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err = gcry_cipher_gettag (hd, buf + noncelen + seskey->keylen, 16);
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if (err)
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goto leave;
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*r_enckeylen = noncelen + seskey->keylen + 16;
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*r_enckey = buf;
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buf = NULL;
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}
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else
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{
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/* In the old version 4 SKESK the encrypted session key is
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* prefixed with a one-octet algorithm id. */
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buf = xtrymalloc_secure (1 + seskey->keylen);
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if (!buf)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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buf[0] = seskey->algo;
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memcpy (buf + 1, seskey->key, seskey->keylen);
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err = openpgp_cipher_open (&hd, dek->algo, GCRY_CIPHER_MODE_CFB, 1);
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if (!err)
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err = gcry_cipher_setkey (hd, dek->key, dek->keylen);
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if (!err)
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err = gcry_cipher_setiv (hd, NULL, 0);
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if (!err)
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err = gcry_cipher_encrypt (hd, buf, seskey->keylen + 1, NULL, 0);
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if (err)
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goto leave;
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*r_enckeylen = seskey->keylen + 1;
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*r_enckey = buf;
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buf = NULL;
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}
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/* The encrypted session key is prefixed with a one-octet algorithm id. */
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buf[0] = seskey->algo;
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memcpy (buf + 1, seskey->key, seskey->keylen);
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err = openpgp_cipher_open (&hd, dek->algo, GCRY_CIPHER_MODE_CFB, 1);
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if (!err)
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err = gcry_cipher_setkey (hd, dek->key, dek->keylen);
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if (!err)
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err = gcry_cipher_setiv (hd, NULL, 0);
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if (!err)
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err = gcry_cipher_encrypt (hd, buf, seskey->keylen + 1, NULL, 0);
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if (err)
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goto leave;
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*r_enckey = buf;
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buf = NULL;
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*r_enckeylen = seskey->keylen + 1;
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/* Return the session key in case we allocated it. */
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*r_seskey = seskey;
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seskey = NULL;
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@ -332,7 +388,7 @@ encrypt_simple (const char *filename, int mode, int use_seskey)
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{
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DEK *dek = NULL;
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rc = encrypt_seskey (cfx.dek, &dek, &enckey, &enckeylen);
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rc = encrypt_seskey (cfx.dek, aead_algo, &dek, &enckey, &enckeylen);
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if (rc)
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{
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xfree (cfx.dek);
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@ -346,14 +402,16 @@ encrypt_simple (const char *filename, int mode, int use_seskey)
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cfx.dek = dek;
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}
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if (opt.verbose)
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log_info(_("using cipher %s\n"),
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openpgp_cipher_algo_name (cfx.dek->algo));
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if (aead_algo)
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cfx.dek->use_aead = aead_algo;
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else
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cfx.dek->use_mdc = !!use_mdc (NULL, cfx.dek->algo);
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if (opt.verbose)
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log_info(_("using cipher %s.%s\n"),
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openpgp_cipher_algo_name (cfx.dek->algo),
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cfx.dek->use_aead? openpgp_aead_algo_name (cfx.dek->use_aead)
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/**/ : "CFB");
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}
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if (do_compress
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@ -385,8 +443,9 @@ encrypt_simple (const char *filename, int mode, int use_seskey)
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{
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/* Fixme: This is quite similar to write_symkey_enc. */
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PKT_symkey_enc *enc = xmalloc_clear (sizeof *enc + enckeylen);
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enc->version = 4;
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enc->version = cfx.dek->use_aead ? 5 : 4;
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enc->cipher_algo = cfx.dek->algo;
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enc->aead_algo = cfx.dek->use_aead;
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enc->s2k = *s2k;
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if (enckeylen)
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{
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@ -535,8 +594,8 @@ setup_symkey (STRING2KEY **symkey_s2k,DEK **symkey_dek)
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static int
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write_symkey_enc (STRING2KEY *symkey_s2k, DEK *symkey_dek, DEK *dek,
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iobuf_t out)
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write_symkey_enc (STRING2KEY *symkey_s2k, aead_algo_t aead_algo,
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DEK *symkey_dek, DEK *dek, iobuf_t out)
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{
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int rc;
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void *enckey;
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@ -544,7 +603,7 @@ write_symkey_enc (STRING2KEY *symkey_s2k, DEK *symkey_dek, DEK *dek,
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PKT_symkey_enc *enc;
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PACKET pkt;
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rc = encrypt_seskey (symkey_dek, &dek, &enckey, &enckeylen);
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rc = encrypt_seskey (symkey_dek, aead_algo, &dek, &enckey, &enckeylen);
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if (rc)
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return rc;
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enc = xtrycalloc (1, sizeof (PKT_symkey_enc) + enckeylen);
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@ -555,8 +614,9 @@ write_symkey_enc (STRING2KEY *symkey_s2k, DEK *symkey_dek, DEK *dek,
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return rc;
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}
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enc->version = 4;
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enc->version = aead_algo? 5 : 4;
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enc->cipher_algo = opt.s2k_cipher_algo;
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enc->aead_algo = aead_algo;
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enc->s2k = *symkey_s2k;
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enc->seskeylen = enckeylen;
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memcpy (enc->seskey, enckey, enckeylen);
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@ -813,10 +873,11 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
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goto leave;
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/* We put the passphrase (if any) after any public keys as this
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seems to be the most useful on the recipient side - there is no
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point in prompting a user for a passphrase if they have the
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secret key needed to decrypt. */
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if(use_symkey && (rc = write_symkey_enc(symkey_s2k,symkey_dek,cfx.dek,out)))
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* seems to be the most useful on the recipient side - there is no
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* point in prompting a user for a passphrase if they have the
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* secret key needed to decrypt. */
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if (use_symkey && (rc = write_symkey_enc (symkey_s2k, cfx.dek->use_aead,
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symkey_dek, cfx.dek, out)))
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goto leave;
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if (!opt.no_literal)
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@ -1014,9 +1075,9 @@ encrypt_filter (void *opaque, int control,
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if(efx->symkey_s2k && efx->symkey_dek)
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{
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rc=write_symkey_enc(efx->symkey_s2k,efx->symkey_dek,
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efx->cfx.dek,a);
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if(rc)
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rc = write_symkey_enc (efx->symkey_s2k, efx->cfx.dek->use_aead,
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efx->symkey_dek, efx->cfx.dek, a);
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if (rc)
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return rc;
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}
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@ -1084,9 +1145,11 @@ write_pubkey_enc (ctrl_t ctrl,
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if ( opt.verbose )
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{
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char *ustr = get_user_id_string_native (ctrl, enc->keyid);
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log_info (_("%s/%s encrypted for: \"%s\"\n"),
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log_info (_("%s/%s.%s encrypted for: \"%s\"\n"),
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openpgp_pk_algo_name (enc->pubkey_algo),
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openpgp_cipher_algo_name (dek->algo),
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dek->use_aead? openpgp_aead_algo_name (dek->use_aead)
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/**/ : "CFB",
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ustr );
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xfree (ustr);
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}
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