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rc4: Initial commit
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saleemrashid authored and prusnak committed Aug 13, 2017
1 parent cc3ab71 commit cb30b58
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Showing 4 changed files with 95 additions and 0 deletions.
1 change: 1 addition & 0 deletions CMakeLists.txt
Expand Up @@ -13,6 +13,7 @@ set(SOURCES
ed25519-donna/ed25519.c ed25519-donna/curve25519-donna-scalarmult-base.c ed25519-donna/ed25519-sha3.c ed25519-donna/ed25519-keccak.c
blake2b.c blake2s.c
chacha20poly1305/chacha20poly1305.c chacha20poly1305/chacha_merged.c chacha20poly1305/poly1305-donna.c chacha20poly1305/rfc7539.c
rc4.c
)

add_library(TrezorCrypto STATIC ${SOURCES})
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1 change: 1 addition & 0 deletions Makefile
Expand Up @@ -48,6 +48,7 @@ SRCS += ed25519-donna/ed25519-donna-basepoint-table.c ed25519-donna/ed25519-don
SRCS += ed25519-donna/ed25519.c ed25519-donna/curve25519-donna-scalarmult-base.c ed25519-donna/ed25519-sha3.c ed25519-donna/ed25519-keccak.c
SRCS += blake2b.c blake2s.c
SRCS += chacha20poly1305/chacha20poly1305.c chacha20poly1305/chacha_merged.c chacha20poly1305/poly1305-donna.c chacha20poly1305/rfc7539.c
SRCS += rc4.c

OBJS = $(SRCS:.c=.o)

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56 changes: 56 additions & 0 deletions rc4.c
@@ -0,0 +1,56 @@
/**
* Copyright (c) 2017 Saleem Rashid
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, E1PRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/

#include "rc4.h"

static inline void rc4_swap(RC4_CTX *ctx, uint8_t i, uint8_t j) {
uint8_t temp = ctx->S[i];
ctx->S[i] = ctx->S[j];
ctx->S[j] = temp;
}

void rc4_init(RC4_CTX *ctx, const uint8_t *key, size_t length) {
ctx->i = 0;
ctx->j = 0;

for (size_t i = 0; i < 256; i++) {
ctx->S[i] = i;
}

uint8_t j = 0;
for (size_t i = 0; i < 256; i++) {
j += ctx->S[i] + key[i % length];
rc4_swap(ctx, i, j);
}
}

void rc4_encrypt(RC4_CTX *ctx, uint8_t *buffer, size_t length) {
for (size_t idx = 0; idx < length; idx++) {
ctx->i++;
ctx->j += ctx->S[ctx->i];

rc4_swap(ctx, ctx->i, ctx->j);

uint8_t K = ctx->S[(ctx->S[ctx->i] + ctx->S[ctx->j]) % 256];
buffer[idx] ^= K;
}
}
37 changes: 37 additions & 0 deletions rc4.h
@@ -0,0 +1,37 @@
/**
* Copyright (c) 2017 Saleem Rashid
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/

#ifndef __RC4_H__
#define __RC4_H__

#include <stdint.h>
#include <stddef.h>

typedef struct {
uint8_t S[256];
uint8_t i, j;
} RC4_CTX;

void rc4_init(RC4_CTX *ctx, const uint8_t *key, size_t length);
void rc4_encrypt(RC4_CTX *ctx, uint8_t *buffer, size_t length);

#endif

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