51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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#include "tomcrypt_private.h"
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/**
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@file ofb_start.c
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OFB implementation, start chain, Tom St Denis
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*/
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#ifdef LTC_OFB_MODE
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/**
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Initialize a OFB context
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@param cipher The index of the cipher desired
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@param IV The initialization vector
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@param key The secret key
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@param keylen The length of the secret key (octets)
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@param num_rounds Number of rounds in the cipher desired (0 for default)
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@param ofb The OFB state to initialize
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@return CRYPT_OK if successful
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*/
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int ofb_start(int cipher, const unsigned char *IV, const unsigned char *key,
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int keylen, int num_rounds, symmetric_OFB *ofb)
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{
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int x, err;
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LTC_ARGCHK(IV != NULL);
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LTC_ARGCHK(key != NULL);
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LTC_ARGCHK(ofb != NULL);
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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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/* init the cipher */
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if ((err = ecb_start(cipher, key, keylen, num_rounds, &ofb->ecb)) != CRYPT_OK) {
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return err;
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}
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ofb->padlen = cipher_descriptor[cipher].block_length;
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/* copy details */
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for (x = 0; x < ofb->ecb.blocklen; x++) {
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ofb->IV[x] = IV[x];
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}
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return CRYPT_OK;
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}
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#endif
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