117 lines
4.4 KiB
C++
117 lines
4.4 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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*
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* Copyright 2013 Danny Robson <danny@nerdcruft.net>
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*/
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#include "md2.hpp"
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#include <cruft/util/std.hpp>
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#include <cruft/util/debug/assert.hpp>
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#include <cruft/util/types.hpp>
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#include <array>
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#include <algorithm>
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#include <cstring>
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///////////////////////////////////////////////////////////////////////////////
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using cruft::crypto::hash::MD2;
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///////////////////////////////////////////////////////////////////////////////
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static constexpr std::array<u08,256> S = { {
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41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6, 19,
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98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188, 76, 130, 202,
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30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24, 138, 23, 229, 18,
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190, 78, 196, 214, 218, 158, 222, 73, 160, 251, 245, 142, 187, 47, 238, 122,
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169, 104, 121, 145, 21, 178, 7, 63, 148, 194, 16, 137, 11, 34, 95, 33,
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128, 127, 93, 154, 90, 144, 50, 39, 53, 62, 204, 231, 191, 247, 151, 3,
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255, 25, 48, 179, 72, 165, 181, 209, 215, 94, 146, 42, 172, 86, 170, 198,
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79, 184, 56, 210, 150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241,
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69, 157, 112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2,
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27, 96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
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85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197, 234, 38,
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44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65, 129, 77, 82,
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106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123, 8, 12, 189, 177, 74,
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120, 136, 149, 139, 227, 99, 232, 109, 233, 203, 213, 254, 59, 0, 29, 57,
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242, 239, 183, 14, 102, 88, 208, 228, 166, 119, 114, 248, 235, 117, 75, 10,
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49, 68, 80, 180, 143, 237, 31, 26, 219, 153, 141, 51, 159, 17, 131, 20,
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} };
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//-----------------------------------------------------------------------------
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static const size_t M_OFFSET = 16;
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static const size_t M_LENGTH = 16;
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///////////////////////////////////////////////////////////////////////////////
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static void
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transform (std::array<u08,16> &C, std::array<u08,48> &X) noexcept
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{
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cruft::view M { X.data () + M_OFFSET, M_LENGTH };
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// Update the checksum.
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// XXX: I can't see why we need the xor-assign from the spec, but it's the
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// only change keeping us from conforming to the test-cases. Pulled from a
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// review of the reference implementation.
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u08 L = C[15];
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for (size_t i = 0; i < std::size (C); ++i)
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L = C[i] ^= S[M[i] ^ L];
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// Setup the blocks
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for (int i = 0; i < 16; ++i)
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X[32 + i] = X[16 + i] ^ X[i];
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// Perform the processing rounds
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for (int i = 0, t = 0; i < 18; ++i) {
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for (auto &j: X)
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t = j ^= S[t];
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t = (t + i) % 256;
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}
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}
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///////////////////////////////////////////////////////////////////////////////
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MD2::digest_t
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MD2::operator() (cruft::view<u08 const*> const data) const noexcept
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{
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// zero initialise the state vectors, and create a simple window `M' into
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// the middle of the `X' state vector.
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std::array<u08,16> C {};
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std::array<u08,48> X {};
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const cruft::view M { std::begin (X) + M_OFFSET, M_LENGTH };
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// process each complete block by copying to the window `M' and
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// transforming X and C.
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//
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// leave the remainder of the data in `M' for subsequent padding.
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auto remain = data;
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while (remain.size () >= M_LENGTH) {
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std::copy_n (std::begin (remain), M_LENGTH, std::begin (M));
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transform (C, X);
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remain = { remain.begin () + M_LENGTH, remain.end () };
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};
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// Copying the remaining data then append the padding bytes. Padding
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// _must_ be performed even if we have an evenly divisible input buffer.
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auto tail = std::copy (remain.begin (), remain.end (), std::begin (M));
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auto unused = std::distance (tail, std::end (M));
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std::fill (tail, std::end (M), unused);
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transform (C, X);
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// Append the checksum and transform once more.
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std::copy (std::begin (C), std::end (C), std::begin (M));
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transform (C, X);
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// The final digest is the first `n' bytes of the state vector.
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digest_t d;
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std::copy_n (std::begin (X), d.size (), std::begin (d));
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return d;
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}
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