pmac_init.rar_pmac

/* */ #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 $ */