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