84 lines
1.9 KiB
C++
84 lines
1.9 KiB
C++
#include <iostream>
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#include <sstream>
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#include <array>
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#include <bitset>
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#define BLOCK_SIZE 16
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#define FEISTELBLOCK_SIZE (BLOCK_SIZE / 2)
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#define N_ROUNDS 8
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typedef std::bitset<BLOCK_SIZE> Block;
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typedef std::bitset<FEISTELBLOCK_SIZE> Feistelblock;
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Feistelblock F(Feistelblock m, const Feistelblock& key);
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std::pair<Feistelblock, Feistelblock> Feistel(Feistelblock l, Feistelblock r, const std::array<Feistelblock, 8>& keys, bool reverseKeyOrder = false);
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int Mod(int numerator, int denominator)
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{
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return (denominator + (numerator % denominator)) % denominator;
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}
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int main()
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{
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Feistelblock l = 0b10101010;
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Feistelblock r = 0b10101010;
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const std::array<Feistelblock, N_ROUNDS> keys = {
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0b11101101,
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0b01110101,
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0b10111101,
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0b00010110,
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0b00000011,
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0b10110011,
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0b11011101,
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0b00111101
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};
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std::cout << "Input: " << l << r << std::endl;
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auto c = Feistel(l, r, keys);
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l = c.first;
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r = c.second;
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std::cout << "Ciphertext: " << l << r << std::endl;
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c = Feistel(l, r, keys, true);
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l = c.first;
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r = c.second;
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std::cout << "Decrypted: " << l << r << std::endl;
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return 0;
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}
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std::pair<Feistelblock, Feistelblock> Feistel(Feistelblock l, Feistelblock r, const std::array<Feistelblock, 8>& keys, bool reverseKeyOrder)
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{
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Feistelblock tmp;
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for (std::size_t i = 0; i < N_ROUNDS; i++)
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{
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// Calculate key index
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std::size_t keyIndex;
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if (reverseKeyOrder)
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keyIndex = N_ROUNDS - i - 1;
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else
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keyIndex = i;
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// Do a feistel round
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tmp = r;
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r = l ^ F(r, keys[keyIndex]);
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l = tmp;
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}
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return std::make_pair(r, l);
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}
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Feistelblock F(Feistelblock m, const Feistelblock& key)
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{
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// Made-up F function
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// Shift 5 to the left
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m <<= 5;
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// Xor with key
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return m ^ key;
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}
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