270 lines
7.2 KiB
C
270 lines
7.2 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
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*/
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/* RC5 code by Tom St Denis */
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#include "mycrypt.h"
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#ifdef RC5
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const struct _cipher_descriptor rc5_desc =
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{
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"rc5",
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2,
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8, 128, 8, 12,
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&rc5_setup,
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&rc5_ecb_encrypt,
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&rc5_ecb_decrypt,
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&rc5_test,
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&rc5_keysize
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};
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static const ulong32 stab[50] = {
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0xb7e15163UL, 0x5618cb1cUL, 0xf45044d5UL, 0x9287be8eUL, 0x30bf3847UL, 0xcef6b200UL, 0x6d2e2bb9UL, 0x0b65a572UL,
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0xa99d1f2bUL, 0x47d498e4UL, 0xe60c129dUL, 0x84438c56UL, 0x227b060fUL, 0xc0b27fc8UL, 0x5ee9f981UL, 0xfd21733aUL,
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0x9b58ecf3UL, 0x399066acUL, 0xd7c7e065UL, 0x75ff5a1eUL, 0x1436d3d7UL, 0xb26e4d90UL, 0x50a5c749UL, 0xeedd4102UL,
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0x8d14babbUL, 0x2b4c3474UL, 0xc983ae2dUL, 0x67bb27e6UL, 0x05f2a19fUL, 0xa42a1b58UL, 0x42619511UL, 0xe0990ecaUL,
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0x7ed08883UL, 0x1d08023cUL, 0xbb3f7bf5UL, 0x5976f5aeUL, 0xf7ae6f67UL, 0x95e5e920UL, 0x341d62d9UL, 0xd254dc92UL,
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0x708c564bUL, 0x0ec3d004UL, 0xacfb49bdUL, 0x4b32c376UL, 0xe96a3d2fUL, 0x87a1b6e8UL, 0x25d930a1UL, 0xc410aa5aUL,
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0x62482413UL, 0x007f9dccUL
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};
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#ifdef CLEAN_STACK
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static int _rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
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#else
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int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
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#endif
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{
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ulong32 L[64], *S, A, B, i, j, v, s, t, l;
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_ARGCHK(skey != NULL);
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_ARGCHK(key != NULL);
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/* test parameters */
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if (num_rounds == 0) {
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num_rounds = rc5_desc.default_rounds;
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}
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if (num_rounds < 12 || num_rounds > 24) {
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return CRYPT_INVALID_ROUNDS;
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}
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/* key must be between 64 and 1024 bits */
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if (keylen < 8 || keylen > 128) {
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return CRYPT_INVALID_KEYSIZE;
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}
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skey->rc5.rounds = num_rounds;
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S = skey->rc5.K;
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/* copy the key into the L array */
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for (A = i = j = 0; i < (ulong32)keylen; ) {
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A = (A << 8) | ((ulong32)(key[i++] & 255));
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if ((i & 3) == 0) {
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L[j++] = BSWAP(A);
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A = 0;
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}
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}
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if ((keylen & 3) != 0) {
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A <<= (ulong32)((8 * (4 - (keylen&3))));
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L[j++] = BSWAP(A);
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}
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/* setup the S array */
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t = (ulong32)(2 * (num_rounds + 1));
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XMEMCPY(S, stab, t * sizeof(*S));
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/* mix buffer */
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s = 3 * MAX(t, j);
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l = j;
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for (A = B = i = j = v = 0; v < s; v++) {
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A = S[i] = ROL(S[i] + A + B, 3);
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B = L[j] = ROL(L[j] + A + B, (A+B));
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if (++i == t) { i = 0; }
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if (++j == l) { j = 0; }
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}
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return CRYPT_OK;
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}
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#ifdef CLEAN_STACK
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int rc5_setup(const unsigned char *key, int keylen, int num_rounds, symmetric_key *skey)
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{
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int x;
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x = _rc5_setup(key, keylen, num_rounds, skey);
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burn_stack(sizeof(ulong32) * 122 + sizeof(int));
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return x;
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}
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#endif
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#ifdef CLEAN_STACK
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static void _rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
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#else
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void rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
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#endif
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{
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ulong32 A, B, *K;
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int r;
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_ARGCHK(key != NULL);
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_ARGCHK(pt != NULL);
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_ARGCHK(ct != NULL);
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LOAD32L(A, &pt[0]);
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LOAD32L(B, &pt[4]);
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A += key->rc5.K[0];
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B += key->rc5.K[1];
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K = key->rc5.K + 2;
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if ((key->rc5.rounds & 1) == 0) {
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for (r = 0; r < key->rc5.rounds; r += 2) {
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A = ROL(A ^ B, B) + K[0];
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B = ROL(B ^ A, A) + K[1];
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A = ROL(A ^ B, B) + K[2];
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B = ROL(B ^ A, A) + K[3];
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K += 4;
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}
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} else {
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for (r = 0; r < key->rc5.rounds; r++) {
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A = ROL(A ^ B, B) + K[0];
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B = ROL(B ^ A, A) + K[1];
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K += 2;
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}
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}
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STORE32L(A, &ct[0]);
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STORE32L(B, &ct[4]);
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}
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#ifdef CLEAN_STACK
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void rc5_ecb_encrypt(const unsigned char *pt, unsigned char *ct, symmetric_key *key)
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{
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_rc5_ecb_encrypt(pt, ct, key);
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burn_stack(sizeof(ulong32) * 2 + sizeof(int));
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}
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#endif
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#ifdef CLEAN_STACK
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static void _rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
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#else
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void rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
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#endif
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{
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ulong32 A, B, *K;
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int r;
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_ARGCHK(key != NULL);
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_ARGCHK(pt != NULL);
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_ARGCHK(ct != NULL);
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LOAD32L(A, &ct[0]);
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LOAD32L(B, &ct[4]);
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K = key->rc5.K + (key->rc5.rounds << 1);
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if ((key->rc5.rounds & 1) == 0) {
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K -= 2;
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for (r = key->rc5.rounds - 1; r >= 0; r -= 2) {
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B = ROR(B - K[3], A) ^ A;
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A = ROR(A - K[2], B) ^ B;
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B = ROR(B - K[1], A) ^ A;
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A = ROR(A - K[0], B) ^ B;
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K -= 4;
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}
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} else {
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for (r = key->rc5.rounds - 1; r >= 0; r--) {
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B = ROR(B - K[1], A) ^ A;
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A = ROR(A - K[0], B) ^ B;
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K -= 2;
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}
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}
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A -= key->rc5.K[0];
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B -= key->rc5.K[1];
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STORE32L(A, &pt[0]);
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STORE32L(B, &pt[4]);
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}
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#ifdef CLEAN_STACK
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void rc5_ecb_decrypt(const unsigned char *ct, unsigned char *pt, symmetric_key *key)
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{
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_rc5_ecb_decrypt(ct, pt, key);
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burn_stack(sizeof(ulong32) * 2 + sizeof(int));
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}
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#endif
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int rc5_test(void)
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{
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#ifndef LTC_TEST
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return CRYPT_NOP;
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#else
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static const struct {
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unsigned char key[16], pt[8], ct[8];
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} tests[] = {
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{
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{ 0x91, 0x5f, 0x46, 0x19, 0xbe, 0x41, 0xb2, 0x51,
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0x63, 0x55, 0xa5, 0x01, 0x10, 0xa9, 0xce, 0x91 },
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{ 0x21, 0xa5, 0xdb, 0xee, 0x15, 0x4b, 0x8f, 0x6d },
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{ 0xf7, 0xc0, 0x13, 0xac, 0x5b, 0x2b, 0x89, 0x52 }
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},
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{
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{ 0x78, 0x33, 0x48, 0xe7, 0x5a, 0xeb, 0x0f, 0x2f,
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0xd7, 0xb1, 0x69, 0xbb, 0x8d, 0xc1, 0x67, 0x87 },
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{ 0xF7, 0xC0, 0x13, 0xAC, 0x5B, 0x2B, 0x89, 0x52 },
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{ 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 }
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},
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{
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{ 0xDC, 0x49, 0xdb, 0x13, 0x75, 0xa5, 0x58, 0x4f,
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0x64, 0x85, 0xb4, 0x13, 0xb5, 0xf1, 0x2b, 0xaf },
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{ 0x2F, 0x42, 0xB3, 0xB7, 0x03, 0x69, 0xFC, 0x92 },
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{ 0x65, 0xc1, 0x78, 0xb2, 0x84, 0xd1, 0x97, 0xcc }
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}
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};
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unsigned char tmp[2][8];
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int x, y, err;
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symmetric_key key;
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for (x = 0; x < (int)(sizeof(tests) / sizeof(tests[0])); x++) {
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/* setup key */
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if ((err = rc5_setup(tests[x].key, 16, 12, &key)) != CRYPT_OK) {
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return err;
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}
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/* encrypt and decrypt */
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rc5_ecb_encrypt(tests[x].pt, tmp[0], &key);
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rc5_ecb_decrypt(tmp[0], tmp[1], &key);
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/* compare */
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if (memcmp(tmp[0], tests[x].ct, 8) != 0 || memcmp(tmp[1], tests[x].pt, 8) != 0) {
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return CRYPT_FAIL_TESTVECTOR;
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}
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/* now see if we can encrypt all zero bytes 1000 times, decrypt and come back where we started */
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for (y = 0; y < 8; y++) tmp[0][y] = 0;
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for (y = 0; y < 1000; y++) rc5_ecb_encrypt(tmp[0], tmp[0], &key);
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for (y = 0; y < 1000; y++) rc5_ecb_decrypt(tmp[0], tmp[0], &key);
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for (y = 0; y < 8; y++) if (tmp[0][y] != 0) return CRYPT_FAIL_TESTVECTOR;
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}
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return CRYPT_OK;
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#endif
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}
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int rc5_keysize(int *desired_keysize)
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{
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_ARGCHK(desired_keysize != NULL);
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if (*desired_keysize < 8) {
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return CRYPT_INVALID_KEYSIZE;
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} else if (*desired_keysize > 128) {
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*desired_keysize = 128;
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}
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return CRYPT_OK;
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}
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#endif
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