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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
*/
#include "tomcrypt.h"
/**
@file pmac_init.c
PMAC implementation, initialize state, by Tom St Denis
*/
#ifdef LTC_PMAC
static const struct {
int len;
unsigned char poly_div[MAXBLOCKSIZE],
poly_mul[MAXBLOCKSIZE];
} polys[] = {
{
8,
{ 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0D },
{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1B }
}, {
16,
{ 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x43 },
{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x87 }
}
};
/**
Initialize a PMAC state
@param pmac The PMAC state to initialize
@param cipher The index of the desired cipher
@param key The secret key
@param keylen The length of the secret key (octets)
@return CRYPT_OK if successful
*/
int pmac_init(pmac_state *pmac, int cipher, const unsigned char *key, unsigned long keylen)
{
int poly, x, y, m, err;
unsigned char *L;
LTC_ARGCHK(pmac != NULL);
LTC_ARGCHK(key != NULL);
/* valid cipher? */
if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
return err;
}
/* determine which polys to use */
pmac->block_len = cipher_descriptor[cipher].block_length;
for (poly = 0; poly < (int)(sizeof(polys)/sizeof(polys[0])); poly++) {
if (polys[poly].len == pmac->block_len) {
break;
}
}
if (polys[poly].len != pmac->block_len) {
return CRYPT_INVALID_ARG;
}
#ifdef LTC_FAST
if (pmac->block_len % sizeof(LTC_FAST_TYPE)) {
return CRYPT_INVALID_ARG;
}
#endif
/* schedule the key */
if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &pmac->key)) != CRYPT_OK) {
return err;
}
/* allocate L */
L = XMALLOC(pmac->block_len);
if (L == NULL) {
return CRYPT_MEM;
}
/* find L = E[0] */
zeromem(L, pmac->block_len);
if ((err = cipher_descriptor[cipher].ecb_encrypt(L, L, &pmac->key)) != CRYPT_OK) {
goto error;
}
/* find Ls[i] = L << i for i == 0..31 */
XMEMCPY(pmac->Ls[0], L, pmac->block_len);
for (x = 1; x < 32; x++) {
m = pmac->Ls[x-1][0] >> 7;
for (y = 0; y < pmac->block_len-1; y++) {
pmac->Ls[x][y] = ((pmac->Ls[x-1][y] << 1) | (pmac->Ls[x-1][y+1] >> 7)) & 255;
}
pmac->Ls[x][pmac->block_len-1] = (pmac->Ls[x-1][pmac->block_len-1] << 1) & 255;
if (m == 1) {
for (y = 0; y < pmac->block_len; y++) {
pmac->Ls[x][y] ^= polys[poly].poly_mul[y];
}
}
}
/* find Lr = L / x */
m = L[pmac->block_len-1] & 1;
/* shift right */
for (x = pmac->block_len - 1; x > 0; x--) {
pmac->Lr[x] = ((L[x] >> 1) | (L[x-1] << 7)) & 255;
}
pmac->Lr[0] = L[0] >> 1;
if (m == 1) {
for (x = 0; x < pmac->block_len; x++) {
pmac->Lr[x] ^= polys[poly].poly_div[x];
}
}
/* zero buffer, counters, etc... */
pmac->block_index = 1;
pmac->cipher_idx = cipher;
pmac->buflen = 0;
zeromem(pmac->block, sizeof(pmac->block));
zeromem(pmac->Li, sizeof(pmac->Li));
zeromem(pmac->checksum, sizeof(pmac->checksum));
err = CRYPT_OK;
error:
#ifdef LTC_CLEAN_STACK
zeromem(L, pmac->block_len);
#endif
XFREE(L);
return err;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/mac/pmac/pmac_init.c,v $ */
/* $Revision: 1.7 $ */
/* $Date: 2006/11/03 00:39:49 $ */
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