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119 lines
3.2 KiB
C
119 lines
3.2 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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#include "tomcrypt.h"
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/**
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@file lrw_process.c
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LRW_MODE implementation, Encrypt/decrypt blocks, Tom St Denis
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*/
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#ifdef LTC_LRW_MODE
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/**
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Process blocks with LRW, since decrypt/encrypt are largely the same they share this code.
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@param pt The "input" data
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@param ct [out] The "output" data
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@param len The length of the input, must be a multiple of 128-bits (16 octets)
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@param mode LRW_ENCRYPT or LRW_DECRYPT
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@param lrw The LRW state
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@return CRYPT_OK if successful
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*/
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int lrw_process(const unsigned char *pt, unsigned char *ct, unsigned long len, int mode, symmetric_LRW *lrw)
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{
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unsigned char prod[16];
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int x, err;
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#ifdef LTC_LRW_TABLES
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int y;
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#endif
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LTC_ARGCHK(pt != NULL);
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LTC_ARGCHK(ct != NULL);
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LTC_ARGCHK(lrw != NULL);
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if (len & 15) {
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return CRYPT_INVALID_ARG;
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}
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while (len) {
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/* copy pad */
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XMEMCPY(prod, lrw->pad, 16);
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/* increment IV */
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for (x = 15; x >= 0; x--) {
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lrw->IV[x] = (lrw->IV[x] + 1) & 255;
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if (lrw->IV[x]) {
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break;
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}
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}
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/* update pad */
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#ifdef LTC_LRW_TABLES
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/* for each byte changed we undo it's affect on the pad then add the new product */
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for (; 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(lrw->pad + y)) ^= *(LTC_FAST_TYPE_PTR_CAST(&lrw->PC[x][lrw->IV[x]][y])) ^ *(LTC_FAST_TYPE_PTR_CAST(&lrw->PC[x][(lrw->IV[x]-1)&255][y]));
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}
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#else
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for (y = 0; y < 16; y++) {
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lrw->pad[y] ^= lrw->PC[x][lrw->IV[x]][y] ^ lrw->PC[x][(lrw->IV[x]-1)&255][y];
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}
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#endif
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}
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#else
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gcm_gf_mult(lrw->tweak, lrw->IV, lrw->pad);
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#endif
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/* xor prod */
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#ifdef LTC_FAST
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for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
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*(LTC_FAST_TYPE_PTR_CAST(ct + x)) = *(LTC_FAST_TYPE_PTR_CAST(pt + x)) ^ *(LTC_FAST_TYPE_PTR_CAST(prod + x));
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}
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#else
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for (x = 0; x < 16; x++) {
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ct[x] = pt[x] ^ prod[x];
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}
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#endif
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/* send through cipher */
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if (mode == LRW_ENCRYPT) {
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if ((err = cipher_descriptor[lrw->cipher].ecb_encrypt(ct, ct, &lrw->key)) != CRYPT_OK) {
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return err;
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}
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} else {
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if ((err = cipher_descriptor[lrw->cipher].ecb_decrypt(ct, ct, &lrw->key)) != CRYPT_OK) {
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return err;
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}
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}
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/* xor prod */
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#ifdef LTC_FAST
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for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
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*(LTC_FAST_TYPE_PTR_CAST(ct + x)) = *(LTC_FAST_TYPE_PTR_CAST(ct + x)) ^ *(LTC_FAST_TYPE_PTR_CAST(prod + x));
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}
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#else
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for (x = 0; x < 16; x++) {
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ct[x] = ct[x] ^ prod[x];
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}
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#endif
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/* move to next */
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pt += 16;
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ct += 16;
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len -= 16;
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}
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return CRYPT_OK;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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