75 lines
2.5 KiB
C
75 lines
2.5 KiB
C
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/*
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* ChaCha20 256-bit cipher algorithm, RFC7539
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*
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* Copyright (C) 2015 Martin Willi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/bitops.h>
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#include <linux/cryptohash.h>
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#include <asm/unaligned.h>
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#include <crypto/chacha20.h>
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void chacha20_block(u32 *state, u8 *stream)
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{
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u32 x[16];
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int i;
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for (i = 0; i < ARRAY_SIZE(x); i++)
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x[i] = state[i];
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for (i = 0; i < 20; i += 2) {
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x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 16);
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x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 16);
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x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 16);
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x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 16);
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x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 12);
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x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 12);
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x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 12);
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x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 12);
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x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 8);
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x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 8);
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x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 8);
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x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 8);
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x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 7);
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x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 7);
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x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 7);
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x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 7);
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x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 16);
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x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 16);
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x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 16);
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x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 16);
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x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 12);
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x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 12);
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x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 12);
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x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 12);
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x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 8);
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x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 8);
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x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 8);
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x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 8);
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x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 7);
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x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 7);
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x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 7);
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x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 7);
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}
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for (i = 0; i < ARRAY_SIZE(x); i++)
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put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]);
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state[12]++;
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}
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EXPORT_SYMBOL(chacha20_block);
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