102 lines
2.9 KiB
C++
102 lines
2.9 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2017-2018 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_CRYPTO_STREAM_SALSA_HPP
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#define CRUFT_CRYPTO_STREAM_SALSA_HPP
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#include <cstdint>
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#include <array>
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#include <cruft/util/bitwise.hpp>
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#include <cruft/util/endian.hpp>
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namespace cruft::crypto::stream::salsa {
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///////////////////////////////////////////////////////////////////////////
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constexpr
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uint32_t
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R (uint32_t a, uint32_t b, uint32_t c, uint32_t k)
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{
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return b ^ cruft::rotatel (a + c, k);
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}
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///////////////////////////////////////////////////////////////////////////
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constexpr
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std::array<uint32_t,4>
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quarter (std::array<uint32_t,4> y) noexcept
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{
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std::array<uint32_t,4> z {};
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z[1] = R (y[0], y[1], y[3], 7);
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z[2] = R (z[1], y[2], y[0], 9);
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z[3] = R (z[2], y[3], z[1], 13);
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z[0] = R (z[3], y[0], z[2], 18);
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return z;
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}
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///////////////////////////////////////////////////////////////////////////
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constexpr
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std::array<uint32_t,16>
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row (const std::array<uint32_t,16> y) noexcept
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{
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const auto &[z00, z01, z02, z03] = quarter ({y[ 0], y[ 1], y[ 2], y[ 3]});
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const auto &[z05, z06, z07, z04] = quarter ({y[ 5], y[ 6], y[ 7], y[ 4]});
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const auto &[z10, z11, z08, z09] = quarter ({y[10], y[11], y[ 8], y[ 9]});
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const auto &[z15, z12, z13, z14] = quarter ({y[15], y[12], y[13], y[14]});
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return {
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z00, z01, z02, z03,
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z04, z05, z06, z07,
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z08, z09, z10, z11,
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z12, z13, z14, z15
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};
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}
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///////////////////////////////////////////////////////////////////////////
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constexpr
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std::array<uint32_t,16>
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col (const std::array<uint32_t,16> x) noexcept
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{
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const auto &[y00, y04, y08, y12] = quarter ({x[ 0], x[ 4], x[ 8], x[12]});
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const auto &[y05, y09, y13, y01] = quarter ({x[ 5], x[ 9], x[13], x[ 1]});
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const auto &[y10, y14, y02, y06] = quarter ({x[10], x[14], x[ 2], x[ 6]});
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const auto &[y15, y03, y07, y11] = quarter ({x[15], x[ 3], x[ 7], x[11]});
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return {
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y00, y01, y02, y03,
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y04, y05, y06, y07,
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y08, y09, y10, y11,
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y12, y13, y14, y15,
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};
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}
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///////////////////////////////////////////////////////////////////////////
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constexpr
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std::array<uint32_t,16>
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doubleround (const std::array<uint32_t,16> x) noexcept
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{
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return row (col (x));
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}
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}
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namespace cruft::crypto::stream {
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///////////////////////////////////////////////////////////////////////////
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std::array<uint8_t,64>
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salsa20 (const std::array<uint8_t,64>) noexcept;
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}
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#endif
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