297 lines
8.8 KiB
C
297 lines
8.8 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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* gurantee 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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/* OMAC1 Support by Tom St Denis (for 64 and 128 bit block ciphers only) */
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#include "mycrypt.h"
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#ifdef OMAC
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int omac_init(omac_state *omac, int cipher, const unsigned char *key, unsigned long keylen)
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{
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int err, x, y, mask, msb, len;
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_ARGCHK(omac != NULL);
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_ARGCHK(key != NULL);
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/* schedule the key */
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if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
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return err;
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}
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/* now setup the system */
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switch (cipher_descriptor[cipher].block_length) {
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case 8: mask = 0x1B;
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len = 8;
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break;
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case 16: mask = 0x87;
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len = 16;
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break;
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default: return CRYPT_INVALID_ARG;
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}
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if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &omac->key)) != CRYPT_OK) {
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return err;
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}
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/* ok now we need Lu and Lu^2 [calc one from the other] */
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/* first calc L which is Ek(0) */
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zeromem(omac->Lu[0], cipher_descriptor[cipher].block_length);
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cipher_descriptor[cipher].ecb_encrypt(omac->Lu[0], omac->Lu[0], &omac->key);
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/* now do the mults, whoopy! */
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for (x = 0; x < 2; x++) {
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/* if msb(L * u^(x+1)) = 0 then just shift, otherwise shift and xor constant mask */
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msb = omac->Lu[x][0] >> 7;
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/* shift left */
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for (y = 0; y < (len - 1); y++) {
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omac->Lu[x][y] = ((omac->Lu[x][y] << 1) | (omac->Lu[x][y+1] >> 7)) & 255;
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}
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omac->Lu[x][len - 1] = ((omac->Lu[x][len - 1] << 1) ^ (msb ? mask : 0)) & 255;
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/* copy up as require */
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if (x == 0) {
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memcpy(omac->Lu[1], omac->Lu[0], sizeof(omac->Lu[0]));
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}
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}
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/* setup state */
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omac->cipher_idx = cipher;
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omac->buflen = 0;
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omac->blklen = len;
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zeromem(omac->prev, sizeof(omac->prev));
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zeromem(omac->block, sizeof(omac->block));
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return CRYPT_OK;
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}
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int omac_process(omac_state *state, const unsigned char *buf, unsigned long len)
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{
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int err, n, x;
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_ARGCHK(state != NULL);
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_ARGCHK(buf != NULL);
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if ((err = cipher_is_valid(state->cipher_idx)) != CRYPT_OK) {
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return err;
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}
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if ((state->buflen > (int)sizeof(state->block)) || (state->buflen < 0) ||
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(state->blklen > (int)sizeof(state->block)) || (state->buflen > state->blklen)) {
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return CRYPT_INVALID_ARG;
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}
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while (len != 0) {
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/* ok if the block is full we xor in prev, encrypt and replace prev */
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if (state->buflen == state->blklen) {
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for (x = 0; x < state->blklen; x++) {
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state->block[x] ^= state->prev[x];
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}
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cipher_descriptor[state->cipher_idx].ecb_encrypt(state->block, state->prev, &state->key);
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state->buflen = 0;
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}
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/* add bytes */
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n = MIN(len, (unsigned long)(state->blklen - state->buflen));
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memcpy(state->block + state->buflen, buf, n);
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state->buflen += n;
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len -= n;
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buf += n;
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}
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return CRYPT_OK;
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}
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int omac_done(omac_state *state, unsigned char *out, unsigned long *outlen)
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{
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int err, mode, x;
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_ARGCHK(state != NULL);
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_ARGCHK(out != NULL);
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if ((err = cipher_is_valid(state->cipher_idx)) != CRYPT_OK) {
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return err;
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}
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if ((state->buflen > (int)sizeof(state->block)) || (state->buflen < 0) ||
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(state->blklen > (int)sizeof(state->block)) || (state->buflen > state->blklen)) {
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return CRYPT_INVALID_ARG;
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}
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/* figure out mode */
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if (state->buflen != state->blklen) {
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/* add the 0x80 byte */
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state->block[state->buflen++] = 0x80;
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/* pad with 0x00 */
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while (state->buflen < state->blklen) {
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state->block[state->buflen++] = 0x00;
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}
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mode = 1;
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} else {
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mode = 0;
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}
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/* now xor prev + Lu[mode] */
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for (x = 0; x < state->blklen; x++) {
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state->block[x] ^= state->prev[x] ^ state->Lu[mode][x];
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}
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/* encrypt it */
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cipher_descriptor[state->cipher_idx].ecb_encrypt(state->block, state->block, &state->key);
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/* output it */
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for (x = 0; x < state->blklen && (unsigned long)x < *outlen; x++) {
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out[x] = state->block[x];
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}
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*outlen = x;
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#ifdef CLEAN_STACK
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zeromem(state, sizeof(*state));
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#endif
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return CRYPT_OK;
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}
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int omac_memory(int cipher, const unsigned char *key, unsigned long keylen,
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const unsigned char *msg, unsigned long msglen,
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unsigned char *out, unsigned long *outlen)
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{
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int err;
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omac_state omac;
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if ((err = omac_init(&omac, cipher, key, keylen)) != CRYPT_OK) {
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return err;
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}
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if ((err = omac_process(&omac, msg, msglen)) != CRYPT_OK) {
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return err;
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}
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if ((err = omac_done(&omac, out, outlen)) != CRYPT_OK) {
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return err;
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}
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return CRYPT_OK;
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}
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int omac_file(int cipher, const unsigned char *key, unsigned long keylen,
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const char *filename, unsigned char *out, unsigned long *outlen)
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{
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#ifdef NO_FILE
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return CRYPT_NOP;
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#else
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int err, x;
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omac_state omac;
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FILE *in;
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unsigned char buf[512];
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in = fopen(filename, "rb");
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if (in == NULL) {
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return CRYPT_FILE_NOTFOUND;
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}
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if ((err = omac_init(&omac, cipher, key, keylen)) != CRYPT_OK) {
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fclose(in);
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return err;
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}
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do {
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x = fread(buf, 1, sizeof(buf), in);
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if ((err = omac_process(&omac, buf, x)) != CRYPT_OK) {
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fclose(in);
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return err;
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}
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} while (x == sizeof(buf));
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fclose(in);
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if ((err = omac_done(&omac, out, outlen)) != CRYPT_OK) {
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return err;
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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 omac_test(void)
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{
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#if !defined(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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int keylen, msglen;
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unsigned char key[32], msg[64], tag[16];
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} tests[] = {
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{ 16, 0,
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{ 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
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0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c },
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{ 0x00 },
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{ 0xbb, 0x1d, 0x69, 0x29, 0xe9, 0x59, 0x37, 0x28,
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0x7f, 0xa3, 0x7d, 0x12, 0x9b, 0x75, 0x67, 0x46 }
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},
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{ 16, 16,
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{ 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
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0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c },
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{ 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
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0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a },
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{ 0x07, 0x0a, 0x16, 0xb4, 0x6b, 0x4d, 0x41, 0x44,
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0xf7, 0x9b, 0xdd, 0x9d, 0xd0, 0x4a, 0x28, 0x7c }
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},
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{ 16, 40,
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{ 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
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0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c },
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{ 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
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0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
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0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c,
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0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
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0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11 },
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{ 0xdf, 0xa6, 0x67, 0x47, 0xde, 0x9a, 0xe6, 0x30,
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0x30, 0xca, 0x32, 0x61, 0x14, 0x97, 0xc8, 0x27 }
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},
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{ 16, 64,
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{ 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
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0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c },
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{ 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
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0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
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0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c,
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0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
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0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
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0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
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0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17,
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0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10 },
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{ 0x51, 0xf0, 0xbe, 0xbf, 0x7e, 0x3b, 0x9d, 0x92,
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0xfc, 0x49, 0x74, 0x17, 0x79, 0x36, 0x3c, 0xfe }
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}
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};
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unsigned char out[16];
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int x, y, err, idx;
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unsigned long len;
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/* AES can be under rijndael or aes... try to find it */
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if ((idx = find_cipher("aes")) == -1) {
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if ((idx = find_cipher("rijndael")) == -1) {
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return CRYPT_NOP;
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}
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}
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for (x = 0; x < (int)(sizeof(tests)/sizeof(tests[0])); x++) {
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len = sizeof(out);
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if ((err = omac_memory(idx, tests[x].key, tests[x].keylen, tests[x].msg, tests[x].msglen, out, &len)) != CRYPT_OK) {
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return err;
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}
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if (memcmp(out, tests[x].tag, 16) != 0) {
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printf("\n\nTag: ");
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for (y = 0; y < 16; y++) printf("%02x", out[y]); printf("\n\n");
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return CRYPT_FAIL_TESTVECTOR;
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}
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}
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return CRYPT_OK;
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#endif
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}
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#endif
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