Pieter Wuille
8 years ago
parent
663fbae777
commit
e04326fe66
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// Copyright (c) 2017 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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// Based on the public domain implementation 'merged' by D. J. Bernstein
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// See https://cr.yp.to/chacha.html.
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#include "crypto/common.h"
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#include "crypto/chacha20.h"
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#include <string.h>
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constexpr static inline uint32_t rotl32(uint32_t v, int c) { return (v << c) | (v >> (32 - c)); }
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#define QUARTERROUND(a,b,c,d) \
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a += b; d = rotl32(d ^ a, 16); \
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c += d; b = rotl32(b ^ c, 12); \
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a += b; d = rotl32(d ^ a, 8); \
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c += d; b = rotl32(b ^ c, 7);
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static const unsigned char sigma[] = "expand 32-byte k";
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static const unsigned char tau[] = "expand 16-byte k";
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void ChaCha20::SetKey(const unsigned char* k, size_t keylen)
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{
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const unsigned char *constants;
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input[4] = ReadLE32(k + 0);
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input[5] = ReadLE32(k + 4);
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input[6] = ReadLE32(k + 8);
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input[7] = ReadLE32(k + 12);
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if (keylen == 32) { /* recommended */
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k += 16;
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constants = sigma;
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} else { /* keylen == 16 */
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constants = tau;
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}
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input[8] = ReadLE32(k + 0);
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input[9] = ReadLE32(k + 4);
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input[10] = ReadLE32(k + 8);
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input[11] = ReadLE32(k + 12);
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input[0] = ReadLE32(constants + 0);
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input[1] = ReadLE32(constants + 4);
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input[2] = ReadLE32(constants + 8);
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input[3] = ReadLE32(constants + 12);
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input[12] = 0;
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input[13] = 0;
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input[14] = 0;
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input[15] = 0;
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}
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ChaCha20::ChaCha20()
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{
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memset(input, 0, sizeof(input));
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}
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ChaCha20::ChaCha20(const unsigned char* k, size_t keylen)
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{
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SetKey(k, keylen);
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}
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void ChaCha20::SetIV(uint64_t iv)
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{
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input[14] = iv;
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input[15] = iv >> 32;
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}
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void ChaCha20::Seek(uint64_t pos)
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{
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input[12] = pos;
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input[13] = pos >> 32;
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}
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void ChaCha20::Output(unsigned char* c, size_t bytes)
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{
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uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
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uint32_t j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
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unsigned char *ctarget = NULL;
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unsigned char tmp[64];
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unsigned int i;
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if (!bytes) return;
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j0 = input[0];
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j1 = input[1];
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j2 = input[2];
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j3 = input[3];
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j4 = input[4];
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j5 = input[5];
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j6 = input[6];
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j7 = input[7];
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j8 = input[8];
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j9 = input[9];
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j10 = input[10];
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j11 = input[11];
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j12 = input[12];
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j13 = input[13];
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j14 = input[14];
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j15 = input[15];
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for (;;) {
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if (bytes < 64) {
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ctarget = c;
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c = tmp;
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}
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x0 = j0;
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x1 = j1;
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x2 = j2;
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x3 = j3;
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x4 = j4;
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x5 = j5;
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x6 = j6;
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x7 = j7;
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x8 = j8;
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x9 = j9;
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x10 = j10;
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x11 = j11;
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x12 = j12;
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x13 = j13;
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x14 = j14;
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x15 = j15;
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for (i = 20;i > 0;i -= 2) {
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QUARTERROUND( x0, x4, x8,x12)
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QUARTERROUND( x1, x5, x9,x13)
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QUARTERROUND( x2, x6,x10,x14)
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QUARTERROUND( x3, x7,x11,x15)
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QUARTERROUND( x0, x5,x10,x15)
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QUARTERROUND( x1, x6,x11,x12)
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QUARTERROUND( x2, x7, x8,x13)
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QUARTERROUND( x3, x4, x9,x14)
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}
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x0 += j0;
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x1 += j1;
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x2 += j2;
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x3 += j3;
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x4 += j4;
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x5 += j5;
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x6 += j6;
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x7 += j7;
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x8 += j8;
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x9 += j9;
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x10 += j10;
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x11 += j11;
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x12 += j12;
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x13 += j13;
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x14 += j14;
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x15 += j15;
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++j12;
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if (!j12) ++j13;
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WriteLE32(c + 0, x0);
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WriteLE32(c + 4, x1);
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WriteLE32(c + 8, x2);
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WriteLE32(c + 12, x3);
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WriteLE32(c + 16, x4);
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WriteLE32(c + 20, x5);
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WriteLE32(c + 24, x6);
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WriteLE32(c + 28, x7);
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WriteLE32(c + 32, x8);
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WriteLE32(c + 36, x9);
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WriteLE32(c + 40, x10);
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WriteLE32(c + 44, x11);
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WriteLE32(c + 48, x12);
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WriteLE32(c + 52, x13);
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WriteLE32(c + 56, x14);
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WriteLE32(c + 60, x15);
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if (bytes <= 64) {
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if (bytes < 64) {
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for (i = 0;i < bytes;++i) ctarget[i] = c[i];
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}
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input[12] = j12;
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input[13] = j13;
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return;
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}
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bytes -= 64;
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c += 64;
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}
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}
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@ -0,0 +1,26 @@
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// Copyright (c) 2017 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_CRYPTO_CHACHA20_H
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#define BITCOIN_CRYPTO_CHACHA20_H
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#include <stdint.h>
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#include <stdlib.h>
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/** A PRNG class for ChaCha20. */
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class ChaCha20
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{
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private:
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uint32_t input[16];
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public:
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ChaCha20();
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ChaCha20(const unsigned char* key, size_t keylen);
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void SetKey(const unsigned char* key, size_t keylen);
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void SetIV(uint64_t iv);
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void Seek(uint64_t pos);
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void Output(unsigned char* output, size_t bytes);
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};
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#endif // BITCOIN_CRYPTO_CHACHA20_H
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