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/* 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@gmail.com, http://libtomcrypt.com
*/
#include "tomcrypt.h"
/**
@file lrw_setiv.c
LRW_MODE implementation, Set the current IV, Tom St Denis
*/
#ifdef LTC_LRW_MODE
/**
Set the IV for LRW
@param IV The IV, must be 16 octets
@param len Length ... must be 16 :-)
@param lrw The LRW state to update
@return CRYPT_OK if successful
*/
int lrw_setiv(const unsigned char *IV, unsigned long len, symmetric_LRW *lrw)
{
int err;
#ifdef LRW_TABLES
unsigned char T[16];
int x, y;
#endif
LTC_ARGCHK(IV != NULL);
LTC_ARGCHK(lrw != NULL);
if (len != 16) {
return CRYPT_INVALID_ARG;
}
if ((err = cipher_is_valid(lrw->cipher)) != CRYPT_OK) {
return err;
}
/* copy the IV */
XMEMCPY(lrw->IV, IV, 16);
/* check if we have to actually do work */
if (cipher_descriptor[lrw->cipher].accel_lrw_encrypt != NULL && cipher_descriptor[lrw->cipher].accel_lrw_decrypt != NULL) {
/* we have accelerators, let's bail since they don't use lrw->pad anyways */
return CRYPT_OK;
}
#ifdef LRW_TABLES
XMEMCPY(T, &lrw->PC[0][IV[0]][0], 16);
for (x = 1; x < 16; x++) {
#ifdef LTC_FAST
for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
*((LTC_FAST_TYPE *)(T + y)) ^= *((LTC_FAST_TYPE *)(&lrw->PC[x][IV[x]][y]));
}
#else
for (y = 0; y < 16; y++) {
T[y] ^= lrw->PC[x][IV[x]][y];
}
#endif
}
XMEMCPY(lrw->pad, T, 16);
#else
gcm_gf_mult(lrw->tweak, IV, lrw->pad);
#endif
return CRYPT_OK;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/modes/lrw/lrw_setiv.c,v $ */
/* $Revision: 1.12 $ */
/* $Date: 2006/06/29 01:53:13 $ */
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