leonetienne/GCrypt
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Cleanup

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Leonetienne 2021-12-05 16:15:11 +01:00
parent 2e8c64f78d
commit 2b8203c76d
1 changed files with 40 additions and 20 deletions
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60
main.cpp
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@ -10,18 +10,24 @@
typedef std::bitset<BLOCK_SIZE> Block; typedef std::bitset<BLOCK_SIZE> Block;
typedef std::bitset<FEISTELBLOCK_SIZE> Feistelblock; typedef std::bitset<FEISTELBLOCK_SIZE> Feistelblock;
Feistelblock F(Feistelblock m, const Feistelblock& key);
std::pair<Feistelblock, Feistelblock> Feistel(Feistelblock l, Feistelblock r, const std::array<Feistelblock, 8>& keys, bool reverseKeyOrder = false);
int Mod(int numerator, int denominator)
{ // Split a data block into two feistel blocks (into L and R)
return (denominator + (numerator % denominator)) % denominator; std::pair<Feistelblock, Feistelblock> FeistelSplit(const Block& block);
}
// Combine two feistel blocks (L and R) into a regular data block
Block FeistelCombine(const Feistelblock& l, const Feistelblock& r);
// Feistel-cipher
Block Feistel(const Block& data, const std::array<Feistelblock, 8>& keys, bool reverseKeyOrder = false);
// Arbitrary cipher function
Feistelblock F(Feistelblock m, const Feistelblock& key);
int main() int main()
{ {
Feistelblock l = 0b10101010; Block message = 0b1010101010101010;
Feistelblock r = 0b10101010;
const std::array<Feistelblock, N_ROUNDS> keys = { const std::array<Feistelblock, N_ROUNDS> keys = {
0b11101101, 0b11101101,
0b01110101, 0b01110101,
@ -33,24 +39,23 @@ int main()
0b00111101 0b00111101
}; };
std::cout << "Input: " << l << r << std::endl; std::cout << "Input: " << message << std::endl;
auto c = Feistel(l, r, keys); Block ciphertext = Feistel(message, keys);
l = c.first; std::cout << "Ciphertext: " << ciphertext << std::endl;
r = c.second;
std::cout << "Ciphertext: " << l << r << std::endl; Block decrypted = Feistel(ciphertext, keys, true);
std::cout << "Decrypted: " << decrypted << std::endl;
c = Feistel(l, r, keys, true);
l = c.first;
r = c.second;
std::cout << "Decrypted: " << l << r << std::endl;
return 0; return 0;
} }
std::pair<Feistelblock, Feistelblock> Feistel(Feistelblock l, Feistelblock r, const std::array<Feistelblock, 8>& keys, bool reverseKeyOrder) Block Feistel(const Block& data, const std::array<Feistelblock, 8>& keys, bool reverseKeyOrder)
{ {
const auto splitData = FeistelSplit(data);
Feistelblock l = splitData.first;
Feistelblock r = splitData.second;
Feistelblock tmp; Feistelblock tmp;
for (std::size_t i = 0; i < N_ROUNDS; i++) for (std::size_t i = 0; i < N_ROUNDS; i++)
@ -68,7 +73,7 @@ std::pair<Feistelblock, Feistelblock> Feistel(Feistelblock l, Feistelblock r, co
l = tmp; l = tmp;
} }
return std::make_pair(r, l); return FeistelCombine(r, l);
} }
Feistelblock F(Feistelblock m, const Feistelblock& key) Feistelblock F(Feistelblock m, const Feistelblock& key)
@ -81,3 +86,18 @@ Feistelblock F(Feistelblock m, const Feistelblock& key)
// Xor with key // Xor with key
return m ^ key; return m ^ key;
} }
std::pair<Feistelblock, Feistelblock> FeistelSplit(const Block& block)
{
const std::string bits = block.to_string();
Feistelblock l(bits.substr(0, bits.size() / 2));
Feistelblock r(bits.substr(bits.size() / 2));
return std::make_pair(l, r);
}
Block FeistelCombine(const Feistelblock& l, const Feistelblock& r)
{
return Block(l.to_string() + r.to_string());
}