BGN2/bgn2/src/decryption.cpp

#include "decryption.hpp"

int decrypt(const Bipoint<curvepoint_fp_t>& ciphertext, const PublicKey& public_key, const PrivateKey& private_key)
{
	static std::unordered_map<Bipoint<curvepoint_fp_t>, int> memoizer;
	static int max_checked = 0;
	static Bipoint<curvepoint_fp_t> pi_1_curvegen = private_key.pi_1(public_key.get_bipoint_curvegen());

	Bipoint<curvepoint_fp_t> pi_1_ciphertext = private_key.pi_1(ciphertext); 

	auto lookup = memoizer.find(pi_1_ciphertext);
	if (lookup != memoizer.end())
	{
		return lookup->second;
	}

	Bipoint<curvepoint_fp_t> i = pi_1_curvegen * max_checked;
	do
	{
		memoizer[pi_1_ciphertext] = max_checked++;
		i = i + pi_1_curvegen;
	} while (i != pi_1_ciphertext);

	return max_checked - 1;
}

int decrypt(const Bipoint<twistpoint_fp2_t>& ciphertext, const PrivateKey& private_key) // pour les chiffrés de niveau 1
{
	static std::unordered_map<Bipoint<twistpoint_fp2_t>, int> memoizer;
	static int max_checked = 0;
	static Bipoint<twistpoint_fp2_t> pi_2_twistgen = private_key.pi_2(public_key.get_bipoint_twistgen());

	Bipoint<twistpoint_fp2_t> pi_2_ciphertext = private_key.pi_2(ciphertext); 

	auto lookup = memoizer.find(pi_2_ciphertext);
	if (lookup != memoizer.end())
	{
		return lookup->second;
	}

	Bipoint<twistpoint_fp2_t> i = pi_2_twistgen * max_checked;
	do
	{
		memoizer[pi_2_ciphertext] = max_checked++;
		i = i + pi_2_twistgen;
	} while (i != pi_2_ciphertext);

	return max_checked - 1;
}


void decrypt(const Quadripoint& ciphertext, const PrivateKey& private_key)
{
	static std::unordered_map<Quadripoint, int> memoizer;
	static int max_checked = 0;
	static Quadripoint pi_T_pairgen = private_key.pi_T(pairing(public_key.get_bipoint_curvegen(), public_key.get_bipoint_twistgen()));

	Quadripoint pi_T_ciphertext = private_key.pi_T(ciphertext); 

	auto lookup = memoizer.find(pi_T_ciphertext);
	if (lookup != memoizer.end())
	{
		return lookup->second;
	}

	Quadripoint i = pi_T_pairgen ^ max_checked;
	do
	{
		memoizer[pi_2_ciphertext] = max_checked++;
		i = i * pi_T_pairgen;
	} while (i != pi_T_ciphertext);

	return max_checked - 1;
}