67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
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/* 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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/* 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_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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#endif
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