mirror of https://github.com/bitcoin/bitcoin.git
373 lines
10 KiB
C++
373 lines
10 KiB
C++
// Copyright (c) 2017-2022 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 <support/cleanse.h>
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#include <span.h>
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#include <algorithm>
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#include <bit>
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#include <string.h>
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#define QUARTERROUND(a,b,c,d) \
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a += b; d = std::rotl(d ^ a, 16); \
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c += d; b = std::rotl(b ^ c, 12); \
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a += b; d = std::rotl(d ^ a, 8); \
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c += d; b = std::rotl(b ^ c, 7);
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#define REPEAT10(a) do { {a}; {a}; {a}; {a}; {a}; {a}; {a}; {a}; {a}; {a}; } while(0)
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void ChaCha20Aligned::SetKey(Span<const std::byte> key) noexcept
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{
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assert(key.size() == KEYLEN);
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input[0] = ReadLE32(UCharCast(key.data() + 0));
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input[1] = ReadLE32(UCharCast(key.data() + 4));
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input[2] = ReadLE32(UCharCast(key.data() + 8));
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input[3] = ReadLE32(UCharCast(key.data() + 12));
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input[4] = ReadLE32(UCharCast(key.data() + 16));
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input[5] = ReadLE32(UCharCast(key.data() + 20));
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input[6] = ReadLE32(UCharCast(key.data() + 24));
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input[7] = ReadLE32(UCharCast(key.data() + 28));
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input[8] = 0;
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input[9] = 0;
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input[10] = 0;
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input[11] = 0;
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}
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ChaCha20Aligned::~ChaCha20Aligned()
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{
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memory_cleanse(input, sizeof(input));
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}
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ChaCha20Aligned::ChaCha20Aligned(Span<const std::byte> key) noexcept
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{
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SetKey(key);
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}
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void ChaCha20Aligned::Seek(Nonce96 nonce, uint32_t block_counter) noexcept
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{
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input[8] = block_counter;
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input[9] = nonce.first;
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input[10] = nonce.second;
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input[11] = nonce.second >> 32;
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}
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inline void ChaCha20Aligned::Keystream(Span<std::byte> output) noexcept
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{
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unsigned char* c = UCharCast(output.data());
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size_t blocks = output.size() / BLOCKLEN;
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assert(blocks * BLOCKLEN == output.size());
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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 j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
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if (!blocks) return;
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j4 = input[0];
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j5 = input[1];
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j6 = input[2];
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j7 = input[3];
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j8 = input[4];
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j9 = input[5];
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j10 = input[6];
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j11 = input[7];
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j12 = input[8];
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j13 = input[9];
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j14 = input[10];
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j15 = input[11];
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for (;;) {
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x0 = 0x61707865;
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x1 = 0x3320646e;
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x2 = 0x79622d32;
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x3 = 0x6b206574;
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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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// The 20 inner ChaCha20 rounds are unrolled here for performance.
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REPEAT10(
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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 += 0x61707865;
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x1 += 0x3320646e;
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x2 += 0x79622d32;
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x3 += 0x6b206574;
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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 (blocks == 1) {
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input[8] = j12;
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input[9] = j13;
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return;
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}
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blocks -= 1;
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c += BLOCKLEN;
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}
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}
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inline void ChaCha20Aligned::Crypt(Span<const std::byte> in_bytes, Span<std::byte> out_bytes) noexcept
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{
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assert(in_bytes.size() == out_bytes.size());
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const unsigned char* m = UCharCast(in_bytes.data());
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unsigned char* c = UCharCast(out_bytes.data());
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size_t blocks = out_bytes.size() / BLOCKLEN;
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assert(blocks * BLOCKLEN == out_bytes.size());
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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 j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
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if (!blocks) return;
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j4 = input[0];
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j5 = input[1];
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j6 = input[2];
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j7 = input[3];
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j8 = input[4];
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j9 = input[5];
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j10 = input[6];
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j11 = input[7];
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j12 = input[8];
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j13 = input[9];
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j14 = input[10];
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j15 = input[11];
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for (;;) {
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x0 = 0x61707865;
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x1 = 0x3320646e;
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x2 = 0x79622d32;
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x3 = 0x6b206574;
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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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// The 20 inner ChaCha20 rounds are unrolled here for performance.
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REPEAT10(
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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 += 0x61707865;
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x1 += 0x3320646e;
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x2 += 0x79622d32;
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x3 += 0x6b206574;
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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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x0 ^= ReadLE32(m + 0);
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x1 ^= ReadLE32(m + 4);
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x2 ^= ReadLE32(m + 8);
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x3 ^= ReadLE32(m + 12);
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x4 ^= ReadLE32(m + 16);
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x5 ^= ReadLE32(m + 20);
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x6 ^= ReadLE32(m + 24);
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x7 ^= ReadLE32(m + 28);
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x8 ^= ReadLE32(m + 32);
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x9 ^= ReadLE32(m + 36);
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x10 ^= ReadLE32(m + 40);
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x11 ^= ReadLE32(m + 44);
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x12 ^= ReadLE32(m + 48);
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x13 ^= ReadLE32(m + 52);
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x14 ^= ReadLE32(m + 56);
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x15 ^= ReadLE32(m + 60);
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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 (blocks == 1) {
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input[8] = j12;
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input[9] = j13;
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return;
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}
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blocks -= 1;
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c += BLOCKLEN;
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m += BLOCKLEN;
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}
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}
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void ChaCha20::Keystream(Span<std::byte> out) noexcept
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{
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if (out.empty()) return;
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if (m_bufleft) {
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unsigned reuse = std::min<size_t>(m_bufleft, out.size());
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std::copy(m_buffer.end() - m_bufleft, m_buffer.end() - m_bufleft + reuse, out.begin());
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m_bufleft -= reuse;
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out = out.subspan(reuse);
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}
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if (out.size() >= m_aligned.BLOCKLEN) {
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size_t blocks = out.size() / m_aligned.BLOCKLEN;
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m_aligned.Keystream(out.first(blocks * m_aligned.BLOCKLEN));
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out = out.subspan(blocks * m_aligned.BLOCKLEN);
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}
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if (!out.empty()) {
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m_aligned.Keystream(m_buffer);
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std::copy(m_buffer.begin(), m_buffer.begin() + out.size(), out.begin());
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m_bufleft = m_aligned.BLOCKLEN - out.size();
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}
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}
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void ChaCha20::Crypt(Span<const std::byte> input, Span<std::byte> output) noexcept
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{
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assert(input.size() == output.size());
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if (!input.size()) return;
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if (m_bufleft) {
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unsigned reuse = std::min<size_t>(m_bufleft, input.size());
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for (unsigned i = 0; i < reuse; i++) {
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output[i] = input[i] ^ m_buffer[m_aligned.BLOCKLEN - m_bufleft + i];
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}
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m_bufleft -= reuse;
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output = output.subspan(reuse);
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input = input.subspan(reuse);
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}
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if (input.size() >= m_aligned.BLOCKLEN) {
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size_t blocks = input.size() / m_aligned.BLOCKLEN;
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m_aligned.Crypt(input.first(blocks * m_aligned.BLOCKLEN), output.first(blocks * m_aligned.BLOCKLEN));
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output = output.subspan(blocks * m_aligned.BLOCKLEN);
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input = input.subspan(blocks * m_aligned.BLOCKLEN);
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}
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if (!input.empty()) {
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m_aligned.Keystream(m_buffer);
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for (unsigned i = 0; i < input.size(); i++) {
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output[i] = input[i] ^ m_buffer[i];
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}
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m_bufleft = m_aligned.BLOCKLEN - input.size();
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}
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}
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ChaCha20::~ChaCha20()
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{
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memory_cleanse(m_buffer.data(), m_buffer.size());
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}
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void ChaCha20::SetKey(Span<const std::byte> key) noexcept
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{
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m_aligned.SetKey(key);
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m_bufleft = 0;
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memory_cleanse(m_buffer.data(), m_buffer.size());
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}
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FSChaCha20::FSChaCha20(Span<const std::byte> key, uint32_t rekey_interval) noexcept :
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m_chacha20(key), m_rekey_interval(rekey_interval)
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{
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assert(key.size() == KEYLEN);
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}
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void FSChaCha20::Crypt(Span<const std::byte> input, Span<std::byte> output) noexcept
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{
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assert(input.size() == output.size());
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// Invoke internal stream cipher for actual encryption/decryption.
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m_chacha20.Crypt(input, output);
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// Rekey after m_rekey_interval encryptions/decryptions.
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if (++m_chunk_counter == m_rekey_interval) {
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// Get new key from the stream cipher.
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std::byte new_key[KEYLEN];
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m_chacha20.Keystream(new_key);
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// Update its key.
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m_chacha20.SetKey(new_key);
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// Wipe the key (a copy remains inside m_chacha20, where it'll be wiped on the next rekey
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// or on destruction).
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memory_cleanse(new_key, sizeof(new_key));
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// Set the nonce for the new section of output.
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m_chacha20.Seek({0, ++m_rekey_counter}, 0);
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// Reset the chunk counter.
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m_chunk_counter = 0;
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}
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}
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