163 lines
4.3 KiB
C++
163 lines
4.3 KiB
C++
#ifndef CHAOS_CIPHER_DES_DESCRYPT_HPP
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#define CHAOS_CIPHER_DES_DESCRYPT_HPP
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#include "Service/SeArray.hpp"
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namespace Chaos::Cipher::Des::Inner_
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{
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struct Bitwise
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{
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template<uint8_t BitsUsed>
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static uint8_t GetBit(uint64_t value, int_fast8_t bitNumber)
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{
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return (value >> (BitsUsed - bitNumber)) & 0b1;
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}
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template<uint8_t BitsUsed>
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static void SetBit(uint64_t & value, int_fast8_t bitNumber)
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{
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value |= (static_cast<uint64_t>(0b1) << (BitsUsed - bitNumber));
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}
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template<uint8_t BitsUsedIn, uint8_t BitsUsedOut, typename InputIt>
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static uint64_t TableChoice(uint64_t value, InputIt tableBegin, InputIt tableEnd)
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{
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uint64_t result = 0;
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int_fast8_t i = 1;
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for (InputIt it = tableBegin; it != tableEnd; ++it, ++i)
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{
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if (GetBit<BitsUsedIn>(value, *it))
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{
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SetBit<BitsUsedOut>(result, i);
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}
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}
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return result;
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}
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template<uint8_t Bits>
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static constexpr uint64_t Mask()
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{
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return (static_cast<uint64_t>(0b1) << Bits) - static_cast<uint64_t>(0b1);
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}
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template<uint8_t BitsUsed>
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static void Rotl(uint64_t & value, int_fast8_t shift)
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{
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value = ((value << shift) | (value >> (BitsUsed - shift))) & Mask<BitsUsed>();
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}
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template<uint8_t BitsUsedOut>
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static std::pair<uint64_t, uint64_t> Split(uint64_t value)
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{
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return { value >> BitsUsedOut, value & Mask<BitsUsedOut>() };
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}
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template<uint8_t BitsUsedIn>
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static uint64_t Merge(uint64_t lhs, uint64_t rhs)
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{
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return (lhs << BitsUsedIn) | rhs;
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}
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};
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using RawKeyArray = Service::SeArray<uint8_t, 8>;
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class KeySchedule
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{
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public:
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using Key64 = uint64_t;
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using Key56 = uint64_t;
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using RoundKey48 = uint64_t;
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KeySchedule(const RawKeyArray & rawKeyArray)
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{
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Key64 key64 = 0;
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key64 |= static_cast<Key64>(rawKeyArray[7]) << 0;
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key64 |= static_cast<Key64>(rawKeyArray[6]) << 8;
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key64 |= static_cast<Key64>(rawKeyArray[5]) << 16;
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key64 |= static_cast<Key64>(rawKeyArray[4]) << 24;
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key64 |= static_cast<Key64>(rawKeyArray[3]) << 32;
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key64 |= static_cast<Key64>(rawKeyArray[2]) << 40;
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key64 |= static_cast<Key64>(rawKeyArray[1]) << 48;
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key64 |= static_cast<Key64>(rawKeyArray[0]) << 56;
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Key56 key56 = Pc1(key64);
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auto [c28, d28] = Bitwise::Split<28>(key56);
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for (int_fast8_t i = 0; i < Schedule_.Size(); ++i)
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{
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if (i == 0 || i == 1 || i == 8 || i == 15)
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{
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Bitwise::Rotl<28>(c28, 1);
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Bitwise::Rotl<28>(d28, 1);
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}
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else
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{
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Bitwise::Rotl<28>(c28, 2);
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Bitwise::Rotl<28>(d28, 2);
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}
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Schedule_[i] = Pc2(Bitwise::Merge<28>(c28, d28));
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}
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}
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RoundKey48 operator[](int_fast8_t i) const
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{
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return Schedule_[i];
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}
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private:
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Service::SeArray<RoundKey48, 16> Schedule_;
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static Key56 Pc1(Key64 key)
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{
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constexpr int_fast8_t PC1_TABLE[] =
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{
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57, 49, 41, 33, 25, 17, 9,
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1, 58, 50, 42, 34, 26, 18,
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10, 2, 59, 51, 43, 35, 27,
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19, 11, 3, 60, 52, 44, 36,
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63, 55, 47, 39, 31, 23, 15,
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7, 62, 54, 46, 38, 30, 22,
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14, 6, 61, 53, 45, 37, 29,
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21, 13, 5, 28, 20, 12, 4
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};
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static_assert(std::size(PC1_TABLE) == 56);
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return Bitwise::TableChoice<64, 56>(key,
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PC1_TABLE,
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PC1_TABLE + std::size(PC1_TABLE));
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}
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static RoundKey48 Pc2(Key56 key)
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{
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constexpr int_fast8_t PC2_TABLE[] =
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{
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14, 17, 11, 24, 1, 5,
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3, 28, 15, 6, 21, 10,
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23, 19, 12, 4, 26, 8,
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16, 7, 27, 20, 13, 2,
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41, 52, 31, 37, 47, 55,
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30, 40, 51, 45, 33, 48,
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44, 49, 39, 56, 34, 53,
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46, 42, 50, 36, 29, 32
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};
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static_assert(std::size(PC2_TABLE) == 48);
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return Bitwise::TableChoice<56, 48>(key,
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PC2_TABLE,
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PC2_TABLE + std::size(PC2_TABLE));
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}
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};
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} // namespace Chaos::Cipher::Des::Inner_
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#endif // CHAOS_CIPHER_DES_DESCRYPT_HPP
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