| /* 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 |
| */ |
| #include "mycrypt.h" |
| |
| #ifdef CTR |
| |
| int ctr_start(int cipher, const unsigned char *count, const unsigned char *key, int keylen, |
| int num_rounds, symmetric_CTR *ctr) |
| { |
| int x, err; |
| |
| _ARGCHK(count != NULL); |
| _ARGCHK(key != NULL); |
| _ARGCHK(ctr != NULL); |
| |
| /* bad param? */ |
| if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { |
| return err; |
| } |
| |
| /* setup cipher */ |
| if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) { |
| return err; |
| } |
| |
| /* copy ctr */ |
| ctr->blocklen = cipher_descriptor[cipher].block_length; |
| ctr->cipher = cipher; |
| ctr->padlen = 0; |
| ctr->mode = 0; |
| for (x = 0; x < ctr->blocklen; x++) { |
| ctr->ctr[x] = count[x]; |
| } |
| cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key); |
| return CRYPT_OK; |
| } |
| |
| #endif |