/* 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@iahu.ca, http://libtomcrypt.org *//* PMAC implementation by Tom St Denis */#include "mycrypt.h"#ifdef PMACstatic 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 }}};int pmac_init(pmac_state *pmac, int cipher, const unsigned char *key, unsigned long keylen){   int poly, x, y, m, err;   unsigned char L[MAXBLOCKSIZE];   _ARGCHK(pmac  != NULL);   _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;   }      /* schedule the key */   if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &pmac->key)) != CRYPT_OK) {      return err;   }    /* find L = E[0] */   zeromem(L, pmac->block_len);   cipher_descriptor[cipher].ecb_encrypt(L, L, &pmac->key);   /* find Ls[i] = L << i for i == 0..31 */   memcpy(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));#ifdef CLEAN_STACK    zeromem(L, sizeof(L));#endif    return CRYPT_OK;}#endif