+++ /dev/null
-/* 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.
- */
-#include "tomcrypt.h"
-
-/**
- @file lrw_start.c
- LRW_MODE implementation, start mode, Tom St Denis
-*/
-
-#ifdef LTC_LRW_MODE
-
-/**
- Initialize the LRW context
- @param cipher The cipher desired, must be a 128-bit block cipher
- @param IV The index value, must be 128-bits
- @param key The cipher key
- @param keylen The length of the cipher key in octets
- @param tweak The tweak value (second key), must be 128-bits
- @param num_rounds The number of rounds for the cipher (0 == default)
- @param lrw [out] The LRW state
- @return CRYPT_OK on success.
-*/
-int lrw_start( int cipher,
- const unsigned char *IV,
- const unsigned char *key, int keylen,
- const unsigned char *tweak,
- int num_rounds,
- symmetric_LRW *lrw)
-{
- int err;
-#ifdef LTC_LRW_TABLES
- unsigned char B[16];
- int x, y, z, t;
-#endif
-
- LTC_ARGCHK(IV != NULL);
- LTC_ARGCHK(key != NULL);
- LTC_ARGCHK(tweak != NULL);
- LTC_ARGCHK(lrw != NULL);
-
-#ifdef LTC_FAST
- if (16 % sizeof(LTC_FAST_TYPE)) {
- return CRYPT_INVALID_ARG;
- }
-#endif
-
- /* is cipher valid? */
- if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
- return err;
- }
- if (cipher_descriptor[cipher].block_length != 16) {
- return CRYPT_INVALID_CIPHER;
- }
-
- /* schedule key */
- if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &lrw->key)) != CRYPT_OK) {
- return err;
- }
- lrw->cipher = cipher;
-
- /* copy the IV and tweak */
- XMEMCPY(lrw->tweak, tweak, 16);
-
-#ifdef LTC_LRW_TABLES
- /* setup tables */
- /* generate the first table as it has no shifting (from which we make the other tables) */
- zeromem(B, 16);
- for (y = 0; y < 256; y++) {
- B[0] = y;
- gcm_gf_mult(tweak, B, &lrw->PC[0][y][0]);
- }
-
- /* now generate the rest of the tables based the previous table */
- for (x = 1; x < 16; x++) {
- for (y = 0; y < 256; y++) {
- /* now shift it right by 8 bits */
- t = lrw->PC[x-1][y][15];
- for (z = 15; z > 0; z--) {
- lrw->PC[x][y][z] = lrw->PC[x-1][y][z-1];
- }
- lrw->PC[x][y][0] = gcm_shift_table[t<<1];
- lrw->PC[x][y][1] ^= gcm_shift_table[(t<<1)+1];
- }
- }
-#endif
-
- /* generate first pad */
- return lrw_setiv(IV, 16, lrw);
-}
-
-
-#endif
-/* ref: $Format:%D$ */
-/* git commit: $Format:%H$ */
-/* commit time: $Format:%ai$ */