|
|
/*
* cifra - embedded cryptography library * Written in 2014 by Joseph Birr-Pixton <jpixton@gmail.com> * * To the extent possible under law, the author(s) have dedicated all * copyright and related and neighboring rights to this software to the * public domain worldwide. This software is distributed without any * warranty. * * You should have received a copy of the CC0 Public Domain Dedication * along with this software. If not, see * <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
#include "prp.h"
#include "modes.h"
#include "bitops.h"
#include "blockwise.h"
#include <string.h>
#include "tassert.h"
/* CBC */ void cf_cbc_init(cf_cbc *ctx, const cf_prp *prp, void *prpctx, const uint8_t iv[CF_MAXBLOCK]) { ctx->prp = prp; ctx->prpctx = prpctx; memcpy(ctx->block, iv, prp->blocksz); }
void cf_cbc_encrypt(cf_cbc *ctx, const uint8_t *input, uint8_t *output, size_t blocks) { uint8_t buf[CF_MAXBLOCK]; size_t nblk = ctx->prp->blocksz;
while (blocks--) { xor_bb(buf, input, ctx->block, nblk); ctx->prp->encrypt(ctx->prpctx, buf, ctx->block); memcpy(output, ctx->block, nblk); input += nblk; output += nblk; } }
void cf_cbc_decrypt(cf_cbc *ctx, const uint8_t *input, uint8_t *output, size_t blocks) { uint8_t buf[CF_MAXBLOCK]; size_t nblk = ctx->prp->blocksz;
while (blocks--) { ctx->prp->decrypt(ctx->prpctx, input, buf); xor_bb(output, buf, ctx->block, nblk); memcpy(ctx->block, input, nblk); input += nblk; output += nblk; } }
/* CTR */ void cf_ctr_init(cf_ctr *ctx, const cf_prp *prp, void *prpctx, const uint8_t nonce[CF_MAXBLOCK]) { memset(ctx, 0, sizeof *ctx); ctx->counter_offset = 0; ctx->counter_width = prp->blocksz; ctx->prp = prp; ctx->prpctx = prpctx; ctx->nkeymat = 0; memcpy(ctx->nonce, nonce, prp->blocksz); }
void cf_ctr_custom_counter(cf_ctr *ctx, size_t offset, size_t width) { assert(ctx->prp->blocksz <= offset + width); ctx->counter_offset = offset; ctx->counter_width = width; }
static void ctr_next_block(void *vctx, uint8_t *out) { cf_ctr *ctx = vctx; ctx->prp->encrypt(ctx->prpctx, ctx->nonce, out); incr_be(ctx->nonce + ctx->counter_offset, ctx->counter_width); }
void cf_ctr_cipher(cf_ctr *ctx, const uint8_t *input, uint8_t *output, size_t bytes) { cf_blockwise_xor(ctx->keymat, &ctx->nkeymat, ctx->prp->blocksz, input, output, bytes, ctr_next_block, ctx); }
void cf_ctr_discard_block(cf_ctr *ctx) { ctx->nkeymat = 0; }
|