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