1//
2// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
3//
4// Distributed under the Boost Software License, Version 1.0. (See accompanying
5// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6//
7// Official repository: https://github.com/boostorg/beast
8//
9
10//
11// This is a derivative work, original copyright follows:
12//
13
14/*
15 Copyright (c) 2015 Orson Peters <orsonpeters@gmail.com>
16
17 This software is provided 'as-is', without any express or implied warranty. In no event will the
18 authors be held liable for any damages arising from the use of this software.
19
20 Permission is granted to anyone to use this software for any purpose, including commercial
21 applications, and to alter it and redistribute it freely, subject to the following restrictions:
22
23 1. The origin of this software must not be misrepresented; you must not claim that you wrote the
24 original software. If you use this software in a product, an acknowledgment in the product
25 documentation would be appreciated but is not required.
26
27 2. Altered source versions must be plainly marked as such, and must not be misrepresented as
28 being the original software.
29
30 3. This notice may not be removed or altered from any source distribution.
31*/
32
33#ifndef BOOST_BEAST_CORE_DETAIL_CHACHA_HPP
34#define BOOST_BEAST_CORE_DETAIL_CHACHA_HPP
35
36#include <cstdint>
37#include <limits>
38
39namespace boost {
40namespace beast {
41namespace detail {
42
43template<std::size_t R>
44class chacha
45{
46 alignas(16) std::uint32_t block_[16];
47 std::uint32_t keysetup_[8];
48 std::uint64_t ctr_ = 0;
49 int idx_ = 16;
50
51 void generate_block()
52 {
53 std::uint32_t constexpr constants[4] = {
54 0x61707865, 0x3320646e, 0x79622d32, 0x6b206574 };
55 std::uint32_t input[16];
56 for (int i = 0; i < 4; ++i)
57 input[i] = constants[i];
58 for (int i = 0; i < 8; ++i)
59 input[4 + i] = keysetup_[i];
60 input[12] = (ctr_ / 16) & 0xffffffffu;
61 input[13] = (ctr_ / 16) >> 32;
62 input[14] = input[15] = 0xdeadbeef; // Could use 128-bit counter.
63 for (int i = 0; i < 16; ++i)
64 block_[i] = input[i];
65 chacha_core();
66 for (int i = 0; i < 16; ++i)
67 block_[i] += input[i];
68 }
69
70 void chacha_core()
71 {
72 #define BOOST_BEAST_CHACHA_ROTL32(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
73
74 #define BOOST_BEAST_CHACHA_QUARTERROUND(x, a, b, c, d) \
75 x[a] = x[a] + x[b]; x[d] ^= x[a]; x[d] = BOOST_BEAST_CHACHA_ROTL32(x[d], 16); \
76 x[c] = x[c] + x[d]; x[b] ^= x[c]; x[b] = BOOST_BEAST_CHACHA_ROTL32(x[b], 12); \
77 x[a] = x[a] + x[b]; x[d] ^= x[a]; x[d] = BOOST_BEAST_CHACHA_ROTL32(x[d], 8); \
78 x[c] = x[c] + x[d]; x[b] ^= x[c]; x[b] = BOOST_BEAST_CHACHA_ROTL32(x[b], 7)
79
80 for (unsigned i = 0; i < R; i += 2)
81 {
82 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 0, 4, 8, 12);
83 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 1, 5, 9, 13);
84 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 2, 6, 10, 14);
85 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 3, 7, 11, 15);
86 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 0, 5, 10, 15);
87 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 1, 6, 11, 12);
88 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 2, 7, 8, 13);
89 BOOST_BEAST_CHACHA_QUARTERROUND(block_, 3, 4, 9, 14);
90 }
91
92 #undef BOOST_BEAST_CHACHA_QUARTERROUND
93 #undef BOOST_BEAST_CHACHA_ROTL32
94 }
95
96public:
97 static constexpr std::size_t state_size = sizeof(chacha::keysetup_);
98
99 using result_type = std::uint32_t;
100
101 chacha(std::uint32_t const* v, std::uint64_t stream)
102 {
103 for (int i = 0; i < 6; ++i)
104 keysetup_[i] = v[i];
105 keysetup_[6] = v[6] + (stream & 0xffffffff);
106 keysetup_[7] = v[7] + ((stream >> 32) & 0xffffffff);
107 }
108
109 std::uint32_t
110 operator()()
111 {
112 if(idx_ == 16)
113 {
114 idx_ = 0;
115 ++ctr_;
116 generate_block();
117 }
118 return block_[idx_++];
119 }
120};
121
122} // detail
123} // beast
124} // boost
125
126#endif
127

source code of boost/libs/beast/include/boost/beast/core/detail/chacha.hpp