#pragma once
#include "Keyset.h"
#include "Block.h"
#include "Halfblock.h"

/** Class to perform a feistel block chipher
*/
class Feistel
{
public:
	Feistel(const Block& key);
	~Feistel();

	//! Will set the seed-key for this feistel network.
	//! Roundkeys will be derived from this.
	void SetKey(const Block& key);

	//! Will encipher a data block via the set seed-key
	Block Encipher(const Block& data);

	//! Will decipher a data block via the set seed-key
	Block Decipher(const Block& data);

private:
	//! Will run the feistel rounds, with either regular key order or reversed key order
	Block Run(const Block& data, bool reverseKeys);

	//! Arbitrary cipher function
	static Halfblock F(Halfblock m, const Block& key);

	//! Split a data block into two half blocks (into L and R)
	static std::pair<Halfblock, Halfblock> FeistelSplit(const Block& block);

	//! Combine two half blocks (L and R) into a regular data block
	static Block FeistelCombine(const Halfblock& l, const Halfblock& r);

	//! Will expand a halfblock to a fullblock
	static Block ExpansionFunction(const Halfblock& block);

	//! Will compress a fullblock to a halfblock
	static Halfblock CompressionFunction(const Block& block);

	//! Substitutes four bits by static random others
	static std::string SBox(const std::string& in);

	//! Will generate a the round keys
	void GenerateRoundKeys(const Block& seedKey);

	//! Will zero the memory used by the keyset
	void ZeroKeyMemory();

	Keyset roundKeys;
};