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/* gost28147.c - GOST 28147-89 implementation for Libgcrypt
* Copyright (C) 2012 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
/* GOST 28147-89 defines several modes of encryption:
* - ECB which should be used only for key transfer
* - CFB mode
* - OFB-like mode with additional transformation on keystream
* RFC 5830 names this 'counter encryption' mode
* Original GOST text uses the term 'gammirovanie'
* - MAC mode
*
* This implementation handles ECB and CFB modes via usual libgcrypt handling.
* OFB-like and MAC modes are unsupported.
*/
#include <config.h>
#include "types.h"
#include "g10lib.h"
#include "cipher.h"
#include "bufhelp.h"
#include "gost.h"
#include "gost-sb.h"
static gcry_err_code_t
gost_setkey (void *c, const byte *key, unsigned keylen)
{
int i;
GOST28147_context *ctx = c;
if (keylen != 256 / 8)
return GPG_ERR_INV_KEYLEN;
if (!ctx->sbox)
ctx->sbox = sbox_test_3411;
for (i = 0; i < 8; i++)
{
ctx->key[i] = buf_get_le32(&key[4*i]);
}
return GPG_ERR_NO_ERROR;
}
static u32
gost_val (GOST28147_context *ctx, u32 cm1, int subkey)
{
cm1 += ctx->key[subkey];
cm1 = ctx->sbox[0*256 + ((cm1 >> 0) & 0xff)] |
ctx->sbox[1*256 + ((cm1 >> 8) & 0xff)] |
ctx->sbox[2*256 + ((cm1 >> 16) & 0xff)] |
ctx->sbox[3*256 + ((cm1 >> 24) & 0xff)];
return cm1;
}
static unsigned int
gost_encrypt_block (void *c, byte *outbuf, const byte *inbuf)
{
GOST28147_context *ctx = c;
u32 n1, n2;
n1 = buf_get_le32 (inbuf);
n2 = buf_get_le32 (inbuf+4);
n2 ^= gost_val (ctx, n1, 0); n1 ^= gost_val (ctx, n2, 1);
n2 ^= gost_val (ctx, n1, 2); n1 ^= gost_val (ctx, n2, 3);
n2 ^= gost_val (ctx, n1, 4); n1 ^= gost_val (ctx, n2, 5);
n2 ^= gost_val (ctx, n1, 6); n1 ^= gost_val (ctx, n2, 7);
n2 ^= gost_val (ctx, n1, 0); n1 ^= gost_val (ctx, n2, 1);
n2 ^= gost_val (ctx, n1, 2); n1 ^= gost_val (ctx, n2, 3);
n2 ^= gost_val (ctx, n1, 4); n1 ^= gost_val (ctx, n2, 5);
n2 ^= gost_val (ctx, n1, 6); n1 ^= gost_val (ctx, n2, 7);
n2 ^= gost_val (ctx, n1, 0); n1 ^= gost_val (ctx, n2, 1);
n2 ^= gost_val (ctx, n1, 2); n1 ^= gost_val (ctx, n2, 3);
n2 ^= gost_val (ctx, n1, 4); n1 ^= gost_val (ctx, n2, 5);
n2 ^= gost_val (ctx, n1, 6); n1 ^= gost_val (ctx, n2, 7);
n2 ^= gost_val (ctx, n1, 7); n1 ^= gost_val (ctx, n2, 6);
n2 ^= gost_val (ctx, n1, 5); n1 ^= gost_val (ctx, n2, 4);
n2 ^= gost_val (ctx, n1, 3); n1 ^= gost_val (ctx, n2, 2);
n2 ^= gost_val (ctx, n1, 1); n1 ^= gost_val (ctx, n2, 0);
buf_put_le32 (outbuf+0, n2);
buf_put_le32 (outbuf+4, n1);
return /* burn_stack */ 4*sizeof(void*) /* func call */ +
3*sizeof(void*) /* stack */ +
4*sizeof(void*) /* gost_val call */;
}
unsigned int _gcry_gost_enc_one (GOST28147_context *c, const byte *key,
byte *out, byte *in, int cryptopro)
{
if (cryptopro)
c->sbox = sbox_CryptoPro_3411;
else
c->sbox = sbox_test_3411;
gost_setkey (c, key, 32);
return gost_encrypt_block (c, out, in) + 5 * sizeof(void *);
}
static unsigned int
gost_decrypt_block (void *c, byte *outbuf, const byte *inbuf)
{
GOST28147_context *ctx = c;
u32 n1, n2;
n1 = buf_get_le32 (inbuf);
n2 = buf_get_le32 (inbuf+4);
n2 ^= gost_val (ctx, n1, 0); n1 ^= gost_val (ctx, n2, 1);
n2 ^= gost_val (ctx, n1, 2); n1 ^= gost_val (ctx, n2, 3);
n2 ^= gost_val (ctx, n1, 4); n1 ^= gost_val (ctx, n2, 5);
n2 ^= gost_val (ctx, n1, 6); n1 ^= gost_val (ctx, n2, 7);
n2 ^= gost_val (ctx, n1, 7); n1 ^= gost_val (ctx, n2, 6);
n2 ^= gost_val (ctx, n1, 5); n1 ^= gost_val (ctx, n2, 4);
n2 ^= gost_val (ctx, n1, 3); n1 ^= gost_val (ctx, n2, 2);
n2 ^= gost_val (ctx, n1, 1); n1 ^= gost_val (ctx, n2, 0);
n2 ^= gost_val (ctx, n1, 7); n1 ^= gost_val (ctx, n2, 6);
n2 ^= gost_val (ctx, n1, 5); n1 ^= gost_val (ctx, n2, 4);
n2 ^= gost_val (ctx, n1, 3); n1 ^= gost_val (ctx, n2, 2);
n2 ^= gost_val (ctx, n1, 1); n1 ^= gost_val (ctx, n2, 0);
n2 ^= gost_val (ctx, n1, 7); n1 ^= gost_val (ctx, n2, 6);
n2 ^= gost_val (ctx, n1, 5); n1 ^= gost_val (ctx, n2, 4);
n2 ^= gost_val (ctx, n1, 3); n1 ^= gost_val (ctx, n2, 2);
n2 ^= gost_val (ctx, n1, 1); n1 ^= gost_val (ctx, n2, 0);
buf_put_le32 (outbuf+0, n2);
buf_put_le32 (outbuf+4, n1);
return /* burn_stack */ 4*sizeof(void*) /* func call */ +
3*sizeof(void*) /* stack */ +
4*sizeof(void*) /* gost_val call */;
}
static gpg_err_code_t
gost_set_sbox (GOST28147_context *ctx, const char *oid)
{
int i;
for (i = 0; gost_oid_map[i].oid; i++)
{
if (!strcmp(gost_oid_map[i].oid, oid))
{
ctx->sbox = gost_oid_map[i].sbox;
return 0;
}
}
return GPG_ERR_VALUE_NOT_FOUND;
}
static gpg_err_code_t
gost_set_extra_info (void *c, int what, const void *buffer, size_t buflen)
{
GOST28147_context *ctx = c;
gpg_err_code_t ec = 0;
(void)buffer;
(void)buflen;
switch (what)
{
case GCRYCTL_SET_SBOX:
ec = gost_set_sbox (ctx, buffer);
break;
default:
ec = GPG_ERR_INV_OP;
break;
}
return ec;
}
static gcry_cipher_oid_spec_t oids_gost28147[] =
{
/* { "1.2.643.2.2.31.0", GCRY_CIPHER_MODE_CNTGOST }, */
{ "1.2.643.2.2.31.1", GCRY_CIPHER_MODE_CFB },
{ "1.2.643.2.2.31.2", GCRY_CIPHER_MODE_CFB },
{ "1.2.643.2.2.31.3", GCRY_CIPHER_MODE_CFB },
{ "1.2.643.2.2.31.4", GCRY_CIPHER_MODE_CFB },
{ NULL }
};
gcry_cipher_spec_t _gcry_cipher_spec_gost28147 =
{
GCRY_CIPHER_GOST28147, {0, 0},
"GOST28147", NULL, oids_gost28147, 8, 256,
sizeof (GOST28147_context),
gost_setkey,
gost_encrypt_block,
gost_decrypt_block,
NULL, NULL, NULL, gost_set_extra_info,
};
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