mirror of
https://github.com/cryb-to/cryb-to.git
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92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
/*-
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* Copyright (c) 2015 Dag-Erling Smørgrav
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "cryb/impl.h"
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#include <stdint.h>
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#include <string.h>
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#include <cryb/bitwise.h>
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#include <cryb/endian.h>
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#include <cryb/rc4.h>
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void
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rc4_init(rc4_ctx *ctx, cipher_mode mode, const uint8_t *key, size_t keylen)
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{
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unsigned int i, j;
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uint8_t t;
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(void)mode;
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memset(ctx, 0, sizeof *ctx);
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for (i = 0; i < 256; ++i)
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ctx->s[i] = i;
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for (i = j = 0; i < 256; ++i) {
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j = (j + ctx->s[i] + key[i % keylen]) % 256;
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t = ctx->s[i];
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ctx->s[i] = ctx->s[j];
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ctx->s[j] = t;
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}
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}
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void
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rc4_update(rc4_ctx *ctx, const void *in, size_t len, void *out)
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{
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const uint8_t *is = in;
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uint8_t t, k, *os = out;
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unsigned int i;
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for (i = 0; i < len; ++i) {
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ctx->i = ctx->i + 1;
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ctx->j = ctx->j + ctx->s[ctx->i];
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t = ctx->s[ctx->i];
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ctx->s[ctx->i] = ctx->s[ctx->j];
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ctx->s[ctx->j] = t;
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t = ctx->s[ctx->i] + ctx->s[ctx->j];
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k = ctx->s[t];
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*os++ = *is++ ^ k;
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}
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}
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void
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rc4_finish(rc4_ctx *ctx)
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{
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memset(ctx, 0, sizeof *ctx);
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}
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cipher_algorithm rc4_cipher = {
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.name = "rc4",
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.contextlen = sizeof(rc4_ctx),
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.blocklen = 1,
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.keylen = 0,
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.init = (cipher_init_func)rc4_init,
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.update = (cipher_update_func)rc4_update,
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.finish = (cipher_finish_func)rc4_finish,
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};
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