293 строки
8.0 KiB
C
293 строки
8.0 KiB
C
/* cipher-cbc.c - Generic CBC mode implementation
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* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
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* 2005, 2007, 2008, 2009, 2011 Free Software Foundation, Inc.
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*
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* This file is part of Libgcrypt.
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*
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* Libgcrypt is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser general Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* Libgcrypt 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, see <http://www.gnu.org/licenses/>.
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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 "g10lib.h"
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#include "cipher.h"
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#include "./cipher-internal.h"
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#include "bufhelp.h"
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static inline unsigned int
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cbc_encrypt_inner(gcry_cipher_hd_t c, unsigned char *outbuf,
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const unsigned char *inbuf, size_t nblocks, size_t blocksize,
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int is_cbc_cmac)
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{
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unsigned int burn, nburn;
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size_t n;
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burn = 0;
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if (c->bulk.cbc_enc)
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{
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c->bulk.cbc_enc (&c->context.c, c->u_iv.iv, outbuf, inbuf, nblocks,
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is_cbc_cmac);
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}
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else
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{
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gcry_cipher_encrypt_t enc_fn = c->spec->encrypt;
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unsigned char *ivp;
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ivp = c->u_iv.iv;
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for (n=0; n < nblocks; n++ )
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{
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cipher_block_xor (outbuf, inbuf, ivp, blocksize);
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nburn = enc_fn ( &c->context.c, outbuf, outbuf );
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burn = nburn > burn ? nburn : burn;
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ivp = outbuf;
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inbuf += blocksize;
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if (!is_cbc_cmac)
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outbuf += blocksize;
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}
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if (ivp != c->u_iv.iv)
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cipher_block_cpy (c->u_iv.iv, ivp, blocksize);
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}
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return burn;
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}
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gcry_err_code_t
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_gcry_cipher_cbc_encrypt (gcry_cipher_hd_t c,
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unsigned char *outbuf, size_t outbuflen,
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const unsigned char *inbuf, size_t inbuflen)
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{
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size_t blocksize_shift = _gcry_blocksize_shift(c);
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size_t blocksize = 1 << blocksize_shift;
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size_t blocksize_mask = blocksize - 1;
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size_t nblocks = inbuflen >> blocksize_shift;
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int is_cbc_cmac = !!(c->flags & GCRY_CIPHER_CBC_MAC);
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unsigned int burn;
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if (outbuflen < (is_cbc_cmac ? blocksize : inbuflen))
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return GPG_ERR_BUFFER_TOO_SHORT;
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if (inbuflen & blocksize_mask)
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return GPG_ERR_INV_LENGTH;
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burn = cbc_encrypt_inner(c, outbuf, inbuf, nblocks, blocksize, is_cbc_cmac);
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if (burn > 0)
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_gcry_burn_stack (burn + 4 * sizeof(void *));
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return 0;
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}
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gcry_err_code_t
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_gcry_cipher_cbc_cts_encrypt (gcry_cipher_hd_t c,
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unsigned char *outbuf, size_t outbuflen,
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const unsigned char *inbuf, size_t inbuflen)
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{
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size_t blocksize_shift = _gcry_blocksize_shift(c);
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size_t blocksize = 1 << blocksize_shift;
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size_t blocksize_mask = blocksize - 1;
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gcry_cipher_encrypt_t enc_fn = c->spec->encrypt;
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size_t nblocks = inbuflen >> blocksize_shift;
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unsigned int burn, nburn;
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unsigned char *ivp;
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int i;
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if (outbuflen < inbuflen)
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return GPG_ERR_BUFFER_TOO_SHORT;
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if ((inbuflen & blocksize_mask) && !(inbuflen > blocksize))
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return GPG_ERR_INV_LENGTH;
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burn = 0;
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if (inbuflen > blocksize)
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{
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if ((inbuflen & blocksize_mask) == 0)
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nblocks--;
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}
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burn = cbc_encrypt_inner(c, outbuf, inbuf, nblocks, blocksize, 0);
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inbuf += nblocks << blocksize_shift;
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outbuf += nblocks << blocksize_shift;
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if (inbuflen > blocksize)
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{
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/* We have to be careful here, since outbuf might be equal to
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inbuf. */
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size_t restbytes;
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unsigned char b;
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if ((inbuflen & blocksize_mask) == 0)
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restbytes = blocksize;
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else
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restbytes = inbuflen & blocksize_mask;
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outbuf -= blocksize;
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for (ivp = c->u_iv.iv, i = 0; i < restbytes; i++)
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{
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b = inbuf[i];
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outbuf[blocksize + i] = outbuf[i];
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outbuf[i] = b ^ *ivp++;
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}
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for (; i < blocksize; i++)
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outbuf[i] = 0 ^ *ivp++;
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nburn = enc_fn (&c->context.c, outbuf, outbuf);
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burn = nburn > burn ? nburn : burn;
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cipher_block_cpy (c->u_iv.iv, outbuf, blocksize);
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}
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if (burn > 0)
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_gcry_burn_stack (burn + 4 * sizeof(void *));
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return 0;
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}
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static inline unsigned int
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cbc_decrypt_inner(gcry_cipher_hd_t c, unsigned char *outbuf,
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const unsigned char *inbuf, size_t nblocks, size_t blocksize)
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{
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unsigned int burn, nburn;
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size_t n;
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burn = 0;
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if (c->bulk.cbc_dec)
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{
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c->bulk.cbc_dec (&c->context.c, c->u_iv.iv, outbuf, inbuf, nblocks);
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}
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else
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{
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gcry_cipher_decrypt_t dec_fn = c->spec->decrypt;
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for (n = 0; n < nblocks; n++)
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{
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/* Because outbuf and inbuf might be the same, we must not overwrite
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the original ciphertext block. We use LASTIV as intermediate
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storage here because it is not used otherwise. */
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nburn = dec_fn ( &c->context.c, c->lastiv, inbuf );
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burn = nburn > burn ? nburn : burn;
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cipher_block_xor_n_copy_2 (outbuf, c->lastiv, c->u_iv.iv, inbuf,
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blocksize);
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inbuf += blocksize;
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outbuf += blocksize;
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}
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}
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return burn;
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}
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gcry_err_code_t
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_gcry_cipher_cbc_decrypt (gcry_cipher_hd_t c,
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unsigned char *outbuf, size_t outbuflen,
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const unsigned char *inbuf, size_t inbuflen)
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{
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size_t blocksize_shift = _gcry_blocksize_shift(c);
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size_t blocksize = 1 << blocksize_shift;
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size_t blocksize_mask = blocksize - 1;
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size_t nblocks = inbuflen >> blocksize_shift;
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unsigned int burn;
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if (outbuflen < inbuflen)
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return GPG_ERR_BUFFER_TOO_SHORT;
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if (inbuflen & blocksize_mask)
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return GPG_ERR_INV_LENGTH;
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burn = cbc_decrypt_inner(c, outbuf, inbuf, nblocks, blocksize);
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if (burn > 0)
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_gcry_burn_stack (burn + 4 * sizeof(void *));
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return 0;
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}
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gcry_err_code_t
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_gcry_cipher_cbc_cts_decrypt (gcry_cipher_hd_t c,
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unsigned char *outbuf, size_t outbuflen,
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const unsigned char *inbuf, size_t inbuflen)
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{
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size_t blocksize_shift = _gcry_blocksize_shift(c);
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size_t blocksize = 1 << blocksize_shift;
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size_t blocksize_mask = blocksize - 1;
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gcry_cipher_decrypt_t dec_fn = c->spec->decrypt;
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size_t nblocks = inbuflen >> blocksize_shift;
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unsigned int burn, nburn;
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int i;
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if (outbuflen < inbuflen)
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return GPG_ERR_BUFFER_TOO_SHORT;
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if ((inbuflen & blocksize_mask) && !(inbuflen > blocksize))
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return GPG_ERR_INV_LENGTH;
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burn = 0;
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if (inbuflen > blocksize)
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{
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nblocks--;
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if ((inbuflen & blocksize_mask) == 0)
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nblocks--;
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cipher_block_cpy (c->lastiv, c->u_iv.iv, blocksize);
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}
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burn = cbc_decrypt_inner(c, outbuf, inbuf, nblocks, blocksize);
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inbuf += nblocks << blocksize_shift;
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outbuf += nblocks << blocksize_shift;
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if (inbuflen > blocksize)
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{
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size_t restbytes;
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if ((inbuflen & blocksize_mask) == 0)
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restbytes = blocksize;
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else
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restbytes = inbuflen & blocksize_mask;
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cipher_block_cpy (c->lastiv, c->u_iv.iv, blocksize ); /* Save Cn-2. */
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buf_cpy (c->u_iv.iv, inbuf + blocksize, restbytes ); /* Save Cn. */
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nburn = dec_fn ( &c->context.c, outbuf, inbuf );
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burn = nburn > burn ? nburn : burn;
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buf_xor(outbuf, outbuf, c->u_iv.iv, restbytes);
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buf_cpy (outbuf + blocksize, outbuf, restbytes);
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for(i=restbytes; i < blocksize; i++)
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c->u_iv.iv[i] = outbuf[i];
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nburn = dec_fn (&c->context.c, outbuf, c->u_iv.iv);
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burn = nburn > burn ? nburn : burn;
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cipher_block_xor(outbuf, outbuf, c->lastiv, blocksize);
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/* c->lastiv is now really lastlastiv, does this matter? */
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}
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if (burn > 0)
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_gcry_burn_stack (burn + 4 * sizeof(void *));
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return 0;
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}
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