115 lines
3.0 KiB
C
115 lines
3.0 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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/* PMAC implementation by Tom St Denis */
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#include "mycrypt.h"
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#ifdef PMAC
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static const struct {
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int len;
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unsigned char poly_div[MAXBLOCKSIZE],
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poly_mul[MAXBLOCKSIZE];
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} polys[] = {
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{
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8,
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{ 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0D },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1B }
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}, {
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16,
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{ 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x43 },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x87 }
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}
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};
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int pmac_init(pmac_state *pmac, int cipher, const unsigned char *key, unsigned long keylen)
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{
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int poly, x, y, m, err;
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unsigned char L[MAXBLOCKSIZE];
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_ARGCHK(pmac != NULL);
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_ARGCHK(key != NULL);
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/* valid cipher? */
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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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/* determine which polys to use */
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pmac->block_len = cipher_descriptor[cipher].block_length;
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for (poly = 0; poly < (int)(sizeof(polys)/sizeof(polys[0])); poly++) {
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if (polys[poly].len == pmac->block_len) {
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break;
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}
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}
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if (polys[poly].len != pmac->block_len) {
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return CRYPT_INVALID_ARG;
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}
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/* schedule the key */
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if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &pmac->key)) != CRYPT_OK) {
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return err;
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}
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/* find L = E[0] */
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zeromem(L, pmac->block_len);
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cipher_descriptor[cipher].ecb_encrypt(L, L, &pmac->key);
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/* find Ls[i] = L << i for i == 0..31 */
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memcpy(pmac->Ls[0], L, pmac->block_len);
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for (x = 1; x < 32; x++) {
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m = pmac->Ls[x-1][0] >> 7;
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for (y = 0; y < pmac->block_len-1; y++) {
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pmac->Ls[x][y] = ((pmac->Ls[x-1][y] << 1) | (pmac->Ls[x-1][y+1] >> 7)) & 255;
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}
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pmac->Ls[x][pmac->block_len-1] = (pmac->Ls[x-1][pmac->block_len-1] << 1) & 255;
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if (m == 1) {
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for (y = 0; y < pmac->block_len; y++) {
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pmac->Ls[x][y] ^= polys[poly].poly_mul[y];
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}
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}
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}
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/* find Lr = L / x */
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m = L[pmac->block_len-1] & 1;
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/* shift right */
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for (x = pmac->block_len - 1; x > 0; x--) {
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pmac->Lr[x] = ((L[x] >> 1) | (L[x-1] << 7)) & 255;
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}
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pmac->Lr[0] = L[0] >> 1;
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if (m == 1) {
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for (x = 0; x < pmac->block_len; x++) {
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pmac->Lr[x] ^= polys[poly].poly_div[x];
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}
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}
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/* zero buffer, counters, etc... */
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pmac->block_index = 1;
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pmac->cipher_idx = cipher;
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pmac->buflen = 0;
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zeromem(pmac->block, sizeof(pmac->block));
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zeromem(pmac->Li, sizeof(pmac->Li));
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zeromem(pmac->checksum, sizeof(pmac->checksum));
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#ifdef CLEAN_STACK
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zeromem(L, sizeof(L));
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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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