342 lines
12 KiB
C
342 lines
12 KiB
C
/**
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* @file rc2.c
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* @version $Format:%h%d$
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*
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* rc2 cipher implementation.
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*/
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/*
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* Copyright (c) 2013-2017 Rambus Inc.
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* Copyright (c) PeerSec Networks, 2002-2011
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* All Rights Reserved
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*
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* The latest version of this code is available at http://www.matrixssl.org
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*
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* This software is open source; 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 2 of the License, or
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* (at your option) any later version.
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*
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* This General Public License does NOT permit incorporating this software
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* into proprietary programs. If you are unable to comply with the GPL, a
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* commercial license for this software may be purchased from Rambus at
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* http://www.rambus.com/
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*
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* This program is distributed in WITHOUT ANY WARRANTY; without even the
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* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the 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, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* http://www.gnu.org/copyleft/gpl.html
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*/
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/******************************************************************************/
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#include "../cryptoImpl.h"
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#ifdef USE_MATRIX_RC2
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/******************************************************************************/
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static int32_t psRc2InitKey(const unsigned char *key, uint8_t keylen,
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uint8_t rds, psRc2Key_t *skey);
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static void psRc2EncryptBlock(const unsigned char *pt, unsigned char *ct,
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psRc2Key_t *skey);
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static void psRc2DecryptBlock(const unsigned char *ct, unsigned char *pt,
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psRc2Key_t *skey);
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/* 256-entry permutation table, probably derived somehow from pi */
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static const unsigned char permute[256] = {
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217, 120, 249, 196, 25, 221, 181, 237, 40, 233, 253, 121, 74, 160, 216, 157,
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198, 126, 55, 131, 43, 118, 83, 142, 98, 76, 100, 136, 68, 139, 251, 162,
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23, 154, 89, 245, 135, 179, 79, 19, 97, 69, 109, 141, 9, 129, 125, 50,
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189, 143, 64, 235, 134, 183, 123, 11, 240, 149, 33, 34, 92, 107, 78, 130,
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84, 214, 101, 147, 206, 96, 178, 28, 115, 86, 192, 20, 167, 140, 241, 220,
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18, 117, 202, 31, 59, 190, 228, 209, 66, 61, 212, 48, 163, 60, 182, 38,
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111, 191, 14, 218, 70, 105, 7, 87, 39, 242, 29, 155, 188, 148, 67, 3,
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248, 17, 199, 246, 144, 239, 62, 231, 6, 195, 213, 47, 200, 102, 30, 215,
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8, 232, 234, 222, 128, 82, 238, 247, 132, 170, 114, 172, 53, 77, 106, 42,
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150, 26, 210, 113, 90, 21, 73, 116, 75, 159, 208, 94, 4, 24, 164, 236,
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194, 224, 65, 110, 15, 81, 203, 204, 36, 145, 175, 80, 161, 244, 112, 57,
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153, 124, 58, 133, 35, 184, 180, 122, 252, 2, 54, 91, 37, 85, 151, 49,
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45, 93, 250, 152, 227, 138, 146, 174, 5, 223, 41, 16, 103, 108, 186, 201,
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211, 0, 230, 207, 225, 158, 168, 44, 99, 22, 1, 63, 88, 226, 137, 169,
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13, 56, 52, 27, 171, 51, 255, 176, 187, 72, 12, 95, 185, 177, 205, 46,
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197, 243, 219, 71, 229, 165, 156, 119, 10, 166, 32, 104, 254, 127, 193, 173
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};
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/******************************************************************************/
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int32_t psRc2Init(psRc2Cbc_t *ctx, const unsigned char *IV,
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const unsigned char *key, uint8_t keylen)
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{
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int32 x, err;
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if (IV == NULL || key == NULL || ctx == NULL)
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{
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psTraceCrypto("psRc2Init arg fail\n");
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return PS_ARG_FAIL;
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}
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/* setup cipher */
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if ((err = psRc2InitKey(key, keylen, 0, &ctx->key)) != PS_SUCCESS)
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{
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return err;
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}
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/* copy IV */
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for (x = 0; x < RC2_BLOCKLEN; x++)
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{
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ctx->IV[x] = IV[x];
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}
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return PS_SUCCESS;
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}
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/******************************************************************************/
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int32_t psRc2Encrypt(psRc2Cbc_t *ctx, const unsigned char *pt,
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unsigned char *ct, uint32_t len)
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{
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int32 x;
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uint32 i;
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unsigned char tmp[RC2_BLOCKLEN];
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if (pt == NULL || ct == NULL || ctx == NULL || (len & 0x7) != 0)
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{
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psTraceCrypto("Bad parameters to psRc2Encrypt\n");
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return PS_ARG_FAIL;
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}
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for (i = 0; i < len; i += RC2_BLOCKLEN)
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{
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/* xor IV against plaintext */
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for (x = 0; x < RC2_BLOCKLEN; x++)
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{
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tmp[x] = pt[x] ^ ctx->IV[x];
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}
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/* encrypt */
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psRc2EncryptBlock(tmp, ct, &ctx->key);
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/* store IV [ciphertext] for a future block */
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for (x = 0; x < RC2_BLOCKLEN; x++)
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{
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ctx->IV[x] = ct[x];
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}
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ct += RC2_BLOCKLEN;
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pt += RC2_BLOCKLEN;
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}
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Memset(tmp, 0x0, sizeof(tmp));
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return len;
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}
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/******************************************************************************/
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int32_t psRc2Decrypt(psRc2Cbc_t *ctx, const unsigned char *ct,
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unsigned char *pt, uint32_t len)
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{
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int32 x;
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uint32 i;
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unsigned char tmp[RC2_BLOCKLEN], tmp2[RC2_BLOCKLEN];
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if (pt == NULL || ct == NULL || ctx == NULL || (len & 0x7) != 0)
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{
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psTraceCrypto("Bad parameters to psRc2Decrypt\n");
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return PS_ARG_FAIL;
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}
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for (i = 0; i < len; i += RC2_BLOCKLEN)
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{
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/* decrypt the block from ct into tmp */
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psRc2DecryptBlock(ct, tmp, &ctx->key);
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/* xor IV against the plaintext of the previous step */
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for (x = 0; x < RC2_BLOCKLEN; x++)
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{
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/* copy CT in case ct == pt */
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tmp2[x] = ct[x];
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/* actually decrypt the byte */
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pt[x] = tmp[x] ^ ctx->IV[x];
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}
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/* replace IV with this current ciphertext */
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for (x = 0; x < RC2_BLOCKLEN; x++)
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{
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ctx->IV[x] = tmp2[x];
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}
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ct += RC2_BLOCKLEN;
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pt += RC2_BLOCKLEN;
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}
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Memset(tmp, 0x0, sizeof(tmp));
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Memset(tmp2, 0x0, sizeof(tmp2));
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return len;
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}
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/******************************************************************************/
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/**
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Initialize the LTC_RC2 block cipher
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@param key The symmetric key you wish to pass
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@param keylen The key length in bytes
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@param num_rounds The number of rounds desired (0 for default)
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@param skey The key in as scheduled by this function.
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@return CRYPT_OK if successful
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*/
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static int32_t psRc2InitKey(const unsigned char *key, uint8_t keylen,
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uint8_t num_rounds, psRc2Key_t *ctx)
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{
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unsigned char tmp[128];
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uint32_t *xkey;
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uint32_t T8, TM;
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int32_t i, bits;
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/* if (keylen < 8 || keylen > 128) { */
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/* return PS_ARG_FAIL; */
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/* } */
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if (num_rounds != 0 && num_rounds != 16)
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{
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return PS_ARG_FAIL;
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}
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xkey = ctx->xkey;
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for (i = 0; i < (int32) keylen; i++)
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{
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tmp[i] = key[i] & 255;
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}
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/* Phase 1: Expand input key to 128 bytes */
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if (keylen < 128)
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{
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for (i = keylen; i < 128; i++)
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{
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tmp[i] = permute[(tmp[i - 1] + tmp[i - keylen]) & 255];
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}
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}
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/* Phase 2 - reduce effective key size to "bits" */
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bits = keylen << 3;
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T8 = (uint32_t) (bits + 7) >> 3;
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TM = (255 >> (uint32_t) (7 & - bits));
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tmp[128 - T8] = permute[tmp[128 - T8] & TM];
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for (i = 127 - T8; i >= 0; i--)
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{
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tmp[i] = permute[tmp[i + 1] ^ tmp[i + T8]];
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}
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/* Phase 3 - copy to xkey in little-endian order */
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for (i = 0; i < 64; i++)
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{
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xkey[i] = (uint32_t) tmp[2 * i] + ((uint32_t) tmp[2 * i + 1] << 8);
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}
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return PS_SUCCESS;
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}
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/******************************************************************************/
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/**
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Encrypts a block of text with LTC_RC2
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@param pt The input plaintext (8 bytes)
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@param ct The output ciphertext (8 bytes)
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@param skey The key as scheduled
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@return CRYPT_OK if successful
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*/
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static void psRc2EncryptBlock(const unsigned char *pt, unsigned char *ct,
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psRc2Key_t *ctx)
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{
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uint32_t *xkey;
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uint32_t x76, x54, x32, x10, i;
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xkey = ctx->xkey;
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x76 = ((uint32_t) pt[7] << 8) + (uint32_t) pt[6];
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x54 = ((uint32_t) pt[5] << 8) + (uint32_t) pt[4];
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x32 = ((uint32_t) pt[3] << 8) + (uint32_t) pt[2];
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x10 = ((uint32_t) pt[1] << 8) + (uint32_t) pt[0];
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for (i = 0; i < 16; i++)
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{
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x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4 * i + 0]) & 0xFFFF;
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x10 = ((x10 << 1) | (x10 >> 15));
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x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4 * i + 1]) & 0xFFFF;
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x32 = ((x32 << 2) | (x32 >> 14));
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x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4 * i + 2]) & 0xFFFF;
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x54 = ((x54 << 3) | (x54 >> 13));
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x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4 * i + 3]) & 0xFFFF;
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x76 = ((x76 << 5) | (x76 >> 11));
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if (i == 4 || i == 10)
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{
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x10 = (x10 + xkey[x76 & 63]) & 0xFFFF;
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x32 = (x32 + xkey[x10 & 63]) & 0xFFFF;
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x54 = (x54 + xkey[x32 & 63]) & 0xFFFF;
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x76 = (x76 + xkey[x54 & 63]) & 0xFFFF;
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}
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}
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ct[0] = (unsigned char) x10;
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ct[1] = (unsigned char) (x10 >> 8);
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ct[2] = (unsigned char) x32;
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ct[3] = (unsigned char) (x32 >> 8);
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ct[4] = (unsigned char) x54;
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ct[5] = (unsigned char) (x54 >> 8);
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ct[6] = (unsigned char) x76;
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ct[7] = (unsigned char) (x76 >> 8);
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}
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/******************************************************************************/
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/**
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Decrypts a block of text with LTC_RC2
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@param ct The input ciphertext (8 bytes)
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@param pt The output plaintext (8 bytes)
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@param skey The key as scheduled
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@return CRYPT_OK if successful
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*/
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static void psRc2DecryptBlock(const unsigned char *ct, unsigned char *pt,
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psRc2Key_t *ctx)
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{
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uint32_t x76, x54, x32, x10;
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uint32_t *xkey;
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int i;
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xkey = ctx->xkey;
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x76 = ((uint32_t) ct[7] << 8) + (uint32_t) ct[6];
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x54 = ((uint32_t) ct[5] << 8) + (uint32_t) ct[4];
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x32 = ((uint32_t) ct[3] << 8) + (uint32_t) ct[2];
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x10 = ((uint32_t) ct[1] << 8) + (uint32_t) ct[0];
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for (i = 15; i >= 0; i--)
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{
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if (i == 4 || i == 10)
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{
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x76 = (x76 - xkey[x54 & 63]) & 0xFFFF;
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x54 = (x54 - xkey[x32 & 63]) & 0xFFFF;
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x32 = (x32 - xkey[x10 & 63]) & 0xFFFF;
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x10 = (x10 - xkey[x76 & 63]) & 0xFFFF;
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}
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x76 = ((x76 << 11) | (x76 >> 5));
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x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4 * i + 3])) & 0xFFFF;
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x54 = ((x54 << 13) | (x54 >> 3));
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x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4 * i + 2])) & 0xFFFF;
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x32 = ((x32 << 14) | (x32 >> 2));
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x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4 * i + 1])) & 0xFFFF;
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x10 = ((x10 << 15) | (x10 >> 1));
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x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4 * i + 0])) & 0xFFFF;
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}
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pt[0] = (unsigned char) x10;
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pt[1] = (unsigned char) (x10 >> 8);
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pt[2] = (unsigned char) x32;
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pt[3] = (unsigned char) (x32 >> 8);
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pt[4] = (unsigned char) x54;
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pt[5] = (unsigned char) (x54 >> 8);
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pt[6] = (unsigned char) x76;
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pt[7] = (unsigned char) (x76 >> 8);
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}
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#endif /* USE_RC2 */
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/******************************************************************************/
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