47 lines
1.2 KiB
C
47 lines
1.2 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
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*/
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#include "mycrypt.h"
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#ifdef CTR
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int ctr_start(int cipher, const unsigned char *count, const unsigned char *key, int keylen,
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int num_rounds, symmetric_CTR *ctr)
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{
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int x, err;
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_ARGCHK(count != NULL);
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_ARGCHK(key != NULL);
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_ARGCHK(ctr != NULL);
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/* bad param? */
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if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
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return err;
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}
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/* setup cipher */
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if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) {
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return err;
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}
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/* copy ctr */
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ctr->blocklen = cipher_descriptor[cipher].block_length;
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ctr->cipher = cipher;
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ctr->padlen = 0;
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ctr->mode = 0;
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for (x = 0; x < ctr->blocklen; x++) {
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ctr->ctr[x] = count[x];
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}
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cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key);
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return CRYPT_OK;
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}
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#endif
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