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![NIIBE Yutaka](/assets/img/avatar_default.png)
* g10/cipher-aead.c (do_flush): No cast is correct. * g10/decrypt-data.c (aead_underflow): No cast needed. Use "%j" for uint64_t for chunklen. Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
449 lines
12 KiB
C
449 lines
12 KiB
C
/* cipher-aead.c - Enciphering filter for AEAD modes
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* Copyright (C) 2018 Werner koch
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses/>.
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* SPDX-License-Identifier: GPL-3.0+
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include "gpg.h"
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#include "../common/status.h"
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#include "../common/iobuf.h"
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#include "../common/util.h"
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#include "filter.h"
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#include "packet.h"
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#include "options.h"
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#include "main.h"
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/* The size of the buffer we allocate to encrypt the data. This must
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* be a multiple of the OCB blocksize (16 byte). */
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#define AEAD_ENC_BUFFER_SIZE (64*1024)
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/* Wrapper around iobuf_write to make sure that a proper error code is
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* always returned. */
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static gpg_error_t
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my_iobuf_write (iobuf_t a, const void *buffer, size_t buflen)
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{
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if (iobuf_write (a, buffer, buflen))
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{
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gpg_error_t err = iobuf_error (a);
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if (!err || !gpg_err_code (err)) /* (The latter should never happen) */
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err = gpg_error (GPG_ERR_EIO);
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return err;
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}
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return 0;
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}
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/* Set the nonce and the additional data for the current chunk. If
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* FINAL is set the final AEAD chunk is processed. This also reset
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* the encryption machinery so that the handle can be used for a new
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* chunk. */
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static gpg_error_t
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set_nonce_and_ad (cipher_filter_context_t *cfx, int final)
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{
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gpg_error_t err;
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unsigned char nonce[16];
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unsigned char ad[21];
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int i;
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switch (cfx->dek->use_aead)
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{
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case AEAD_ALGO_OCB:
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memcpy (nonce, cfx->startiv, 15);
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i = 7;
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break;
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case AEAD_ALGO_EAX:
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memcpy (nonce, cfx->startiv, 16);
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i = 8;
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break;
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default:
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BUG ();
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}
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nonce[i++] ^= cfx->chunkindex >> 56;
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nonce[i++] ^= cfx->chunkindex >> 48;
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nonce[i++] ^= cfx->chunkindex >> 40;
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nonce[i++] ^= cfx->chunkindex >> 32;
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nonce[i++] ^= cfx->chunkindex >> 24;
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nonce[i++] ^= cfx->chunkindex >> 16;
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nonce[i++] ^= cfx->chunkindex >> 8;
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nonce[i++] ^= cfx->chunkindex;
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if (DBG_CRYPTO)
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log_printhex (nonce, 15, "nonce:");
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err = gcry_cipher_setiv (cfx->cipher_hd, nonce, i);
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if (err)
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return err;
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ad[0] = (0xc0 | PKT_ENCRYPTED_AEAD);
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ad[1] = 1;
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ad[2] = cfx->dek->algo;
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ad[3] = cfx->dek->use_aead;
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ad[4] = cfx->chunkbyte;
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ad[5] = cfx->chunkindex >> 56;
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ad[6] = cfx->chunkindex >> 48;
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ad[7] = cfx->chunkindex >> 40;
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ad[8] = cfx->chunkindex >> 32;
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ad[9] = cfx->chunkindex >> 24;
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ad[10]= cfx->chunkindex >> 16;
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ad[11]= cfx->chunkindex >> 8;
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ad[12]= cfx->chunkindex;
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if (final)
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{
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ad[13] = cfx->total >> 56;
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ad[14] = cfx->total >> 48;
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ad[15] = cfx->total >> 40;
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ad[16] = cfx->total >> 32;
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ad[17] = cfx->total >> 24;
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ad[18] = cfx->total >> 16;
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ad[19] = cfx->total >> 8;
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ad[20] = cfx->total;
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}
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if (DBG_CRYPTO)
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log_printhex (ad, final? 21 : 13, "authdata:");
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return gcry_cipher_authenticate (cfx->cipher_hd, ad, final? 21 : 13);
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}
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static gpg_error_t
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write_header (cipher_filter_context_t *cfx, iobuf_t a)
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{
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gpg_error_t err;
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PACKET pkt;
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PKT_encrypted ed;
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unsigned int blocksize;
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unsigned int startivlen;
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enum gcry_cipher_modes ciphermode;
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log_assert (cfx->dek->use_aead);
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blocksize = openpgp_cipher_get_algo_blklen (cfx->dek->algo);
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if (blocksize != 16 )
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log_fatal ("unsupported blocksize %u for AEAD\n", blocksize);
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err = openpgp_aead_algo_info (cfx->dek->use_aead, &ciphermode, &startivlen);
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if (err)
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goto leave;
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log_assert (opt.chunk_size >= 6 && opt.chunk_size <= 62);
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cfx->chunkbyte = opt.chunk_size - 6;
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cfx->chunksize = (uint64_t)1 << (cfx->chunkbyte + 6);
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cfx->chunklen = 0;
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cfx->bufsize = AEAD_ENC_BUFFER_SIZE;
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cfx->buflen = 0;
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cfx->buffer = xtrymalloc (cfx->bufsize);
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if (!cfx->buffer)
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return gpg_error_from_syserror ();
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memset (&ed, 0, sizeof ed);
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ed.new_ctb = 1; /* (Is anyway required for the packet type). */
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ed.len = 0; /* fixme: cfx->datalen */
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ed.extralen = startivlen + 16; /* (16 is the taglen) */
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ed.cipher_algo = cfx->dek->algo;
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ed.aead_algo = cfx->dek->use_aead;
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ed.chunkbyte = cfx->chunkbyte;
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init_packet (&pkt);
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pkt.pkttype = PKT_ENCRYPTED_AEAD;
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pkt.pkt.encrypted = &ed;
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if (DBG_FILTER)
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log_debug ("aead packet: len=%lu extralen=%d\n",
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(unsigned long)ed.len, ed.extralen);
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write_status_printf (STATUS_BEGIN_ENCRYPTION, "0 %d %d",
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cfx->dek->algo, ed.aead_algo);
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print_cipher_algo_note (cfx->dek->algo);
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if (build_packet( a, &pkt))
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log_bug ("build_packet(ENCRYPTED_AEAD) failed\n");
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log_assert (sizeof cfx->startiv >= startivlen);
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gcry_randomize (cfx->startiv, startivlen, GCRY_STRONG_RANDOM);
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err = my_iobuf_write (a, cfx->startiv, startivlen);
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if (err)
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goto leave;
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err = openpgp_cipher_open (&cfx->cipher_hd,
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cfx->dek->algo,
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ciphermode,
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GCRY_CIPHER_SECURE);
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if (err)
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goto leave;
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if (DBG_CRYPTO)
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log_printhex (cfx->dek->key, cfx->dek->keylen, "thekey:");
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err = gcry_cipher_setkey (cfx->cipher_hd, cfx->dek->key, cfx->dek->keylen);
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if (err)
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return err;
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cfx->wrote_header = 1;
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leave:
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return err;
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}
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/* Get and write the auth tag to stream A. */
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static gpg_error_t
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write_auth_tag (cipher_filter_context_t *cfx, iobuf_t a)
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{
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gpg_error_t err;
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char tag[16];
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err = gcry_cipher_gettag (cfx->cipher_hd, tag, 16);
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if (err)
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goto leave;
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err = my_iobuf_write (a, tag, 16);
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if (err)
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goto leave;
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leave:
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if (err)
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log_error ("write_auth_tag failed: %s\n", gpg_strerror (err));
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return err;
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}
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/* Write the final chunk to stream A. */
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static gpg_error_t
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write_final_chunk (cipher_filter_context_t *cfx, iobuf_t a)
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{
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gpg_error_t err;
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char dummy[1];
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err = set_nonce_and_ad (cfx, 1);
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if (err)
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goto leave;
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gcry_cipher_final (cfx->cipher_hd);
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/* Encrypt an empty string. */
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err = gcry_cipher_encrypt (cfx->cipher_hd, dummy, 0, NULL, 0);
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if (err)
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goto leave;
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err = write_auth_tag (cfx, a);
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leave:
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return err;
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}
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/* The core of the flush sub-function of cipher_filter_aead. */
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static gpg_error_t
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do_flush (cipher_filter_context_t *cfx, iobuf_t a, byte *buf, size_t size)
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{
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gpg_error_t err = 0;
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int finalize = 0;
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size_t n;
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/* Put the data into a buffer, flush and encrypt as needed. */
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if (DBG_FILTER)
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log_debug ("flushing %zu bytes (cur buflen=%zu)\n", size, cfx->buflen);
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do
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{
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if (cfx->buflen + size < cfx->bufsize)
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n = size;
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else
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n = cfx->bufsize - cfx->buflen;
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if (cfx->chunklen + cfx->buflen + n >= cfx->chunksize)
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{
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size_t n1 = cfx->chunksize - (cfx->chunklen + cfx->buflen);
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finalize = 1;
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if (DBG_FILTER)
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log_debug ("chunksize %ju reached;"
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" cur buflen=%zu using %zu of %zu\n",
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cfx->chunksize, cfx->buflen,
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n1, n);
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n = n1;
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}
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memcpy (cfx->buffer + cfx->buflen, buf, n);
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cfx->buflen += n;
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buf += n;
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size -= n;
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if (cfx->buflen == cfx->bufsize || finalize)
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{
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if (DBG_FILTER)
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log_debug ("encrypting: size=%zu buflen=%zu %s n=%zu\n",
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size, cfx->buflen, finalize?"(finalize)":"", n);
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if (!cfx->chunklen)
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{
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if (DBG_FILTER)
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log_debug ("start encrypting a new chunk\n");
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err = set_nonce_and_ad (cfx, 0);
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if (err)
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goto leave;
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}
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if (finalize)
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gcry_cipher_final (cfx->cipher_hd);
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if (DBG_FILTER)
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{
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if (finalize)
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log_printhex (cfx->buffer, cfx->buflen, "plain(1):");
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else if (cfx->buflen > 32)
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log_printhex (cfx->buffer + cfx->buflen - 32, 32,
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"plain(last32):");
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}
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/* Take care: even with a buflen of zero an encrypt needs to
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* be called after gcry_cipher_final and before
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* gcry_cipher_gettag - at least with libgcrypt 1.8 and OCB
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* mode. */
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err = gcry_cipher_encrypt (cfx->cipher_hd, cfx->buffer, cfx->buflen,
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NULL, 0);
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if (err)
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goto leave;
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if (finalize && DBG_FILTER)
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log_printhex (cfx->buffer, cfx->buflen, "ciphr(1):");
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err = my_iobuf_write (a, cfx->buffer, cfx->buflen);
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if (err)
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goto leave;
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cfx->chunklen += cfx->buflen;
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cfx->total += cfx->buflen;
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cfx->buflen = 0;
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if (finalize)
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{
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if (DBG_FILTER)
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log_debug ("writing tag: chunklen=%ju total=%ju\n",
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(uintmax_t)cfx->chunklen, (uintmax_t)cfx->total);
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err = write_auth_tag (cfx, a);
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if (err)
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goto leave;
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cfx->chunkindex++;
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cfx->chunklen = 0;
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finalize = 0;
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}
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}
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}
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while (size);
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leave:
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return err;
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}
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/* The core of the free sub-function of cipher_filter_aead. */
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static gpg_error_t
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do_free (cipher_filter_context_t *cfx, iobuf_t a)
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{
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gpg_error_t err = 0;
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if (DBG_FILTER)
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log_debug ("do_free: buflen=%zu\n", cfx->buflen);
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if (cfx->buflen)
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{
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if (DBG_FILTER)
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log_debug ("encrypting last %zu bytes of the last chunk\n",cfx->buflen);
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if (!cfx->chunklen)
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{
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if (DBG_FILTER)
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log_debug ("start encrypting a new chunk\n");
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err = set_nonce_and_ad (cfx, 0);
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if (err)
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goto leave;
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}
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gcry_cipher_final (cfx->cipher_hd);
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err = gcry_cipher_encrypt (cfx->cipher_hd, cfx->buffer, cfx->buflen,
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NULL, 0);
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if (err)
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goto leave;
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err = my_iobuf_write (a, cfx->buffer, cfx->buflen);
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if (err)
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goto leave;
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/* log_printhex (cfx->buffer, cfx->buflen, "wrote:"); */
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cfx->chunklen += cfx->buflen;
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cfx->total += cfx->buflen;
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/* Get and write the authentication tag. */
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if (DBG_FILTER)
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log_debug ("writing tag: chunklen=%ju total=%ju\n",
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(uintmax_t)cfx->chunklen, (uintmax_t)cfx->total);
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err = write_auth_tag (cfx, a);
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if (err)
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goto leave;
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cfx->chunkindex++;
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cfx->chunklen = 0;
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}
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/* Write the final chunk. */
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if (DBG_FILTER)
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log_debug ("creating final chunk\n");
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err = write_final_chunk (cfx, a);
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leave:
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xfree (cfx->buffer);
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cfx->buffer = NULL;
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gcry_cipher_close (cfx->cipher_hd);
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cfx->cipher_hd = NULL;
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return err;
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}
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/*
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* This filter is used to encrypt data with an AEAD algorithm
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*/
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int
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cipher_filter_aead (void *opaque, int control,
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iobuf_t a, byte *buf, size_t *ret_len)
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{
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cipher_filter_context_t *cfx = opaque;
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size_t size = *ret_len;
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int rc = 0;
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if (control == IOBUFCTRL_UNDERFLOW) /* decrypt */
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{
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rc = -1; /* not used */
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}
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else if (control == IOBUFCTRL_FLUSH) /* encrypt */
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{
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if (!cfx->wrote_header && (rc=write_header (cfx, a)))
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;
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else
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rc = do_flush (cfx, a, buf, size);
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}
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else if (control == IOBUFCTRL_FREE)
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{
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rc = do_free (cfx, a);
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}
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else if (control == IOBUFCTRL_DESC)
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{
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mem2str (buf, "cipher_filter_aead", *ret_len);
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}
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return rc;
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}
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