143 lines
5.2 KiB
C++
143 lines
5.2 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 2018 Danny Robson <danny@nerdcruft.net>
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*/
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#include "rc2.hpp"
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#include <cruft/util/bitwise.hpp>
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#include <cruft/util/endian.hpp>
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using cruft::crypto::block::rc2;
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///////////////////////////////////////////////////////////////////////////////
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static constexpr std::array<u08,256> PITABLE {
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0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed, 0x28, 0xe9, 0xfd, 0x79, 0x4a, 0xa0, 0xd8, 0x9d,
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0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e, 0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2,
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0x17, 0x9a, 0x59, 0xf5, 0x87, 0xb3, 0x4f, 0x13, 0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32,
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0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b, 0xf0, 0x95, 0x21, 0x22, 0x5c, 0x6b, 0x4e, 0x82,
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0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c, 0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc,
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0x12, 0x75, 0xca, 0x1f, 0x3b, 0xbe, 0xe4, 0xd1, 0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26,
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0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57, 0x27, 0xf2, 0x1d, 0x9b, 0xbc, 0x94, 0x43, 0x03,
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0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7, 0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7,
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0x08, 0xe8, 0xea, 0xde, 0x80, 0x52, 0xee, 0xf7, 0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a,
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0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74, 0x4b, 0x9f, 0xd0, 0x5e, 0x04, 0x18, 0xa4, 0xec,
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0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc, 0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39,
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0x99, 0x7c, 0x3a, 0x85, 0x23, 0xb8, 0xb4, 0x7a, 0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31,
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0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae, 0x05, 0xdf, 0x29, 0x10, 0x67, 0x6c, 0xba, 0xc9,
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0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c, 0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9,
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0x0d, 0x38, 0x34, 0x1b, 0xab, 0x33, 0xff, 0xb0, 0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e,
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0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77, 0x0a, 0xa6, 0x20, 0x68, 0xfe, 0x7f, 0xc1, 0xad,
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};
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///////////////////////////////////////////////////////////////////////////////
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rc2::rc2 (
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cruft::view<u08 const*> const key,
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int const effective_bits
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) {
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// Ensure we don't exceed maximum key or effective lengths.
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if (auto len = key.size (); len > 128 || len <= 0)
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throw std::invalid_argument ("invalid key size");
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if (effective_bits > 1024)
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throw std::invalid_argument ("invalid effective key size");
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// Copy the initial raw key bytes into the key area
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auto xkb = cruft::make_byte_view<u08> (m_key);
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std::copy (key.begin (), key.end (), xkb.begin ());
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// Mix bytes from Pi into the remaining region
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if (auto len = key.size (); len < 128) {
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int i = 0;
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for (u08 x = key[len - 1]; len < 128; ++len) {
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x += xkb[i++];
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x &= 0xff;
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x = PITABLE[x];
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xkb[len] = x;
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}
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}
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// Reduce the 'effective' bits of the key
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auto const effective_bytes = cruft::divup (effective_bits, 8);
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int remain = 128 - effective_bytes;
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u08 const mask = 0xff >> (8 * effective_bytes - effective_bits);
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u08 x = xkb[remain] & mask;
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x = PITABLE[x];
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xkb[remain] = x;
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while (remain--) {
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x ^= xkb[remain + effective_bytes];
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x = PITABLE[x];
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xkb[remain] = x;
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}
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// Convert to little endian for output
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for (auto &k: m_key)
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k = cruft::htol (k);
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}
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//-----------------------------------------------------------------------------
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rc2::rc2 (cruft::view<u08 const *> key)
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: rc2 (key, 1024)
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{ ; }
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///////////////////////////////////////////////////////////////////////////////
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std::array<u16,4>
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rc2::encrypt (std::array<u16,4> src) const noexcept
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{
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auto [r0, r1, r2, r3] = src;
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for (int i = 0; i < 16; i++) {
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auto const offset = 4 * i;
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r0 += m_key[offset + 0] + (r3 & r2) + (~r3 & r1); r0 = cruft::rotatel (r0, 1);
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r1 += m_key[offset + 1] + (r0 & r3) + (~r0 & r2); r1 = cruft::rotatel (r1, 2);
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r2 += m_key[offset + 2] + (r1 & r0) + (~r1 & r3); r2 = cruft::rotatel (r2, 3);
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r3 += m_key[offset + 3] + (r2 & r1) + (~r2 & r0); r3 = cruft::rotatel (r3, 5);
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if (i == 4 || i == 10) {
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r0 += m_key[r3 & 63];
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r1 += m_key[r0 & 63];
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r2 += m_key[r1 & 63];
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r3 += m_key[r2 & 63];
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}
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}
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return { r0, r1, r2, r3 };
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}
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//-----------------------------------------------------------------------------
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std::array<u16,4>
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rc2::decrypt (std::array<u16,4> src) const noexcept
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{
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auto [r0,r1,r2,r3] = src;
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for (int i = 15; i >= 0; --i) {
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auto const offset = 4 * i;
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r3 = cruft::rotatel (r3, 11); r3 -= m_key[offset + 3] + (r2 & r1) + (~r2 & r0);
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r2 = cruft::rotatel (r2, 13); r2 -= m_key[offset + 2] + (r1 & r0) + (~r1 & r3);
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r1 = cruft::rotatel (r1, 14); r1 -= m_key[offset + 1] + (r0 & r3) + (~r0 & r2);
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r0 = cruft::rotatel (r0, 15); r0 -= m_key[offset + 0] + (r3 & r2) + (~r3 & r1);
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if (i == 5 || i == 11) {
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r3 -= m_key[r2 & 63];
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r2 -= m_key[r1 & 63];
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r1 -= m_key[r0 & 63];
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r0 -= m_key[r3 & 63];
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}
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}
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return { r0, r1, r2, r3 };
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} |