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/* rc2.c - The RC2 stream cipher
* Copyright (C) 2003 Nikos Mavroyanopoulos
*
* This file is part of GNUTLS.
*
* GNUTLS 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.
*
* GNUTLS 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*
*/
#include <gnutls_int.h>
#include <gnutls_errors.h>
#include <gcrypt.h>
static const char *selftest(void);
typedef struct {
uint16 S[64];
} RC2_context;
static const uint8 rc2_sbox[] = { 217,
120, 249, 196, 25, 221, 181, 237, 40, 233, 253,
121, 74, 160, 216, 157, 198, 126, 55, 131, 43,
118, 83, 142, 98, 76, 100, 136, 68, 139, 251,
162, 23, 154, 89, 245, 135, 179, 79, 19, 97,
69, 109, 141, 9, 129, 125, 50, 189, 143, 64,
235, 134, 183, 123, 11, 240, 149, 33, 34, 92,
107, 78, 130, 84, 214, 101, 147, 206, 96, 178,
28, 115, 86, 192, 20, 167, 140, 241, 220, 18,
117, 202, 31, 59, 190, 228, 209, 66, 61, 212,
48, 163, 60, 182, 38, 111, 191, 14, 218, 70,
105, 7, 87, 39, 242, 29, 155, 188, 148, 67,
3, 248, 17, 199, 246, 144, 239, 62, 231, 6,
195, 213, 47, 200, 102, 30, 215, 8, 232, 234,
222, 128, 82, 238, 247, 132, 170, 114, 172, 53,
77, 106, 42, 150, 26, 210, 113, 90, 21, 73,
116, 75, 159, 208, 94, 4, 24, 164, 236, 194,
224, 65, 110, 15, 81, 203, 204, 36, 145, 175,
80, 161, 244, 112, 57, 153, 124, 58, 133, 35,
184, 180, 122, 252, 2, 54, 91, 37, 85, 151,
49, 45, 93, 250, 152, 227, 138, 146, 174, 5,
223, 41, 16, 103, 108, 186, 201, 211, 0, 230,
207, 225, 158, 168, 44, 99, 22, 1, 63, 88,
226, 137, 169, 13, 56, 52, 27, 171, 51, 255,
176, 187, 72, 12, 95, 185, 177, 205, 46, 197,
243, 219, 71, 229, 165, 156, 119, 10, 166, 32,
104, 254, 127, 193, 173
};
#define rotl16(x,n) (((x) << ((uint16)(n))) | ((x) >> (16 - (uint16)(n))))
#define rotr16(x,n) (((x) >> ((uint16)(n))) | ((x) << (16 - (uint16)(n))))
static void
do_rc2_encrypt( RC2_context *ctx,
uint8 *outbuf, const uint8 *inbuf)
{
register int i, j;
uint16 word0 = 0, word1 = 0, word2 = 0, word3 = 0;
word0 = (word0 << 8) | inbuf[1];
word0 = (word0 << 8) | inbuf[0];
word1 = (word1 << 8) | inbuf[3];
word1 = (word1 << 8) | inbuf[2];
word2 = (word2 << 8) | inbuf[5];
word2 = (word2 << 8) | inbuf[4];
word3 = (word3 << 8) | inbuf[7];
word3 = (word3 << 8) | inbuf[6];
for (i=0;i<16;i++) {
j = i * 4;
/* for some reason I cannot combine those steps.
*/
word0 = word0 + (word1 & ~word3) + (word2 & word3) + ctx->S[ j ];
word0 = rotl16( word0, 1);
word1 = word1 + (word2 & ~word0) + (word3 & word0) + ctx->S[ j+1 ];
word1 = rotl16( word1, 2);
word2 = word2 + (word3 & ~word1) + (word0 & word1) + ctx->S[ j+2 ];
word2 = rotl16( word2, 3);
word3 = word3 + (word0 & ~word2) + (word1 & word2) + ctx->S[ j+3 ];
word3 = rotl16( word3, 5);
if (i==4 || i==10) {
word0 += ctx->S[ word3 & 63 ];
word1 += ctx->S[ word0 & 63 ];
word2 += ctx->S[ word1 & 63 ];
word3 += ctx->S[ word2 & 63 ];
}
}
outbuf[0] = word0 & 255;
outbuf[1] = word0 >> 8;
outbuf[2] = word1 & 255;
outbuf[3] = word1 >> 8;
outbuf[4] = word2 & 255;
outbuf[5] = word2 >> 8;
outbuf[6] = word3 & 255;
outbuf[7] = word3 >> 8;
}
static void
rc2_encrypt (void *context,
uint8 *outbuf, const uint8 *inbuf)
{
RC2_context *ctx = (RC2_context *) context;
do_rc2_encrypt (ctx, outbuf, inbuf);
}
/* Decryption
*/
static void
do_rc2_decrypt( RC2_context *ctx,
uint8 *outbuf, const uint8 *inbuf)
{
register int i, j;
uint16 word0 = 0, word1 = 0, word2 = 0, word3 = 0;
word0 = (word0 << 8) | inbuf[1];
word0 = (word0 << 8) | inbuf[0];
word1 = (word1 << 8) | inbuf[3];
word1 = (word1 << 8) | inbuf[2];
word2 = (word2 << 8) | inbuf[5];
word2 = (word2 << 8) | inbuf[4];
word3 = (word3 << 8) | inbuf[7];
word3 = (word3 << 8) | inbuf[6];
for (i=15;i>=0;i--) {
j = i * 4;
word3 = rotr16( word3, 5);
word3 = word3 - ( word0 & ~word2 ) - ( word1 & word2 ) - ctx->S[j+3];
word2 = rotr16( word2, 3);
word2 = word2 - ( word3 & ~word1 ) - ( word0 & word1 ) - ctx->S[j+2];
word1 = rotr16( word1, 2);
word1 = word1 - ( word2 & ~word0 ) - ( word3 & word0 ) - ctx->S[j+1];
word0 = rotr16( word0, 1);
word0 = word0 - ( word1 & ~word3 ) - ( word2 & word3 ) - ctx->S[j ];
if (i==5 || i==11) {
word3 = word3 - ctx->S[word2 & 63];
word2 = word2 - ctx->S[word1 & 63];
word1 = word1 - ctx->S[word0 & 63];
word0 = word0 - ctx->S[word3 & 63];
}
}
outbuf[0] = word0 & 255;
outbuf[1] = word0 >> 8;
outbuf[2] = word1 & 255;
outbuf[3] = word1 >> 8;
outbuf[4] = word2 & 255;
outbuf[5] = word2 >> 8;
outbuf[6] = word3 & 255;
outbuf[7] = word3 >> 8;
}
static void
rc2_decrypt (void *context,
uint8 *outbuf, const uint8 *inbuf)
{
RC2_context *ctx = (RC2_context *) context;
do_rc2_decrypt (ctx, outbuf, inbuf);
}
static gpg_err_code_t
do_rc2_setkey (void *context, const uint8 *key, unsigned int keylen)
{
static int initialized;
static const char* selftest_failed;
uint i;
uint8 * S, x;
RC2_context *ctx = (RC2_context *) context;
int bits = keylen * 8, len;
#if 0
if( !initialized ) {
initialized = 1;
selftest_failed = selftest();
}
if( selftest_failed )
return GPG_ERR_SELFTEST_FAILED;
#endif
if( keylen < 40/8 ) /* we want at least 40 bits */
return GPG_ERR_INV_KEYLEN;
S = (uint8*) ctx->S;
for (i=0;i<keylen;i++)
S[i] = key[i];
for (i=keylen;i<128;i++)
S[i] = rc2_sbox[ (S[i-keylen] + S[i-1]) & 255 ];
S[0] = rc2_sbox[ S[0]];
/* Phase 2 - reduce effective key size to "bits"
* (copied from the public domain code posted in sci.crypt)
*/
len = (bits+7) >> 3;
i = 128-len;
x = rc2_sbox[S[i] & (255 >> (7 & -bits))];
S[i] = x;
while (i--) {
x = rc2_sbox[ x ^ S[i+len] ];
S[i] = x;
}
/* end of Phase 2
*/
/* Make the expanded key, endian independent.
*/
for(i=0;i<64;i++) {
ctx->S[i] = (uint16)S[i*2] | (((uint16)S[i*2+1]) << 8);
}
return GPG_ERR_NO_ERROR;
}
static gpg_err_code_t
rc2_setkey ( void *context, const uint8 *key, unsigned int keylen)
{
RC2_context *ctx = (RC2_context *) context;
gpg_err_code_t rc = do_rc2_setkey (ctx, key, keylen );
return rc;
}
static const char*
selftest(void)
{
RC2_context ctx;
uint8 scratch[16];
/* Test vectors from Peter Gutmann's paper
*/
static uint8 key_1[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
static uint8 plaintext_1[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
static const uint8 ciphertext_1[] = { 0x1C, 0x19, 0x8A, 0x83, 0x8D, 0xF0, 0x28, 0xB7 };
static uint8 key_2[] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F };
static uint8 plaintext_2[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
static uint8 ciphertext_2[] = { 0x50, 0xDC, 0x01, 0x62, 0xBD, 0x75, 0x7F, 0x31 };
/* This one was checked against libmcrypt's RC2
*/
static uint8 key_3[] = { 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
static uint8 plaintext_3[] = { 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
static uint8 ciphertext_3[] = { 0x8f, 0xd1, 0x03, 0x89, 0x33, 0x6b, 0xf9, 0x5e };
rc2_setkey( &ctx, key_1, sizeof(key_1));
rc2_encrypt( &ctx, scratch, plaintext_1);
if (memcmp (scratch, ciphertext_1, sizeof (ciphertext_1)))
return "RC2 encryption test 1 failed.";
rc2_setkey( &ctx, key_1, sizeof(key_1));
rc2_decrypt(&ctx, scratch, scratch); /* decrypt */
if ( memcmp (scratch, plaintext_1, sizeof (plaintext_1)))
return "RC2 decryption test 1 failed.";
/* Second test
*/
rc2_setkey( &ctx, key_2, sizeof(key_2));
rc2_encrypt( &ctx, scratch, plaintext_2);
if (memcmp (scratch, ciphertext_2, sizeof (ciphertext_2)))
return "RC2 encryption test 2 failed.";
rc2_setkey( &ctx, key_2, sizeof(key_2));
rc2_decrypt(&ctx, scratch, scratch); /* decrypt */
if ( memcmp (scratch, plaintext_2, sizeof (plaintext_2)))
return "RC2 decryption test 2 failed.";
/* Third test
*/
rc2_setkey( &ctx, key_3, sizeof(key_3));
rc2_encrypt( &ctx, scratch, plaintext_3);
if (memcmp (scratch, ciphertext_3, sizeof (ciphertext_3)))
return "RC2 encryption test 3 failed.";
rc2_setkey( &ctx, key_3, sizeof(key_3));
rc2_decrypt(&ctx, scratch, scratch); /* decrypt */
if ( memcmp (scratch, plaintext_3, sizeof (plaintext_3)))
return "RC2 decryption test 3 failed.";
return NULL;
}
static gcry_cipher_spec_t cipher_spec_rc2 =
{
"RC2", NULL, NULL, 8, 40, sizeof (RC2_context),
rc2_setkey, rc2_encrypt, rc2_decrypt,
NULL, NULL
};
int _gcry_rc2_40_id = -1;
static gcry_module_t rc2_40_mod;
int _gnutls_register_rc2_cipher( void)
{
if (gcry_cipher_register( &cipher_spec_rc2,
&_gcry_rc2_40_id, &rc2_40_mod)) {
gnutls_assert();
return GNUTLS_E_INTERNAL_ERROR;
}
return 0;
}
void _gnutls_unregister_rc2_cipher( void)
{
gcry_cipher_unregister( rc2_40_mod);
}
|
