-rw-r--r-- 1247 cryptattacktester-20231020/parity.cpp raw
#include "parity.h"
#include "ram.h"
#include "bit_vector.h"

using namespace std;

bit parity_known(vector<bit> &s, vector<vector<bit>> &H, vector<vector<bit>> &map, const bit known)
{
	s.insert(s.begin(), known);

	for (bigint i = 0; i < H.size(); i++)
		H.at(i).insert(H.at(i).begin(), bit(1));

	// add other rows to the first row
 
	const bigint R = s.size();
	const bigint N = H.size();
	const bigint K = N-R;

	for (bigint j = 1; j < R; j++)
		s.at(0) ^= s.at(j);

	for (bigint i = 0; i < K+1; i++)
	for (bigint j = 1; j < R; j++)
		H.at(i).at(0) ^= H.at(i).at(j);
	
	for (bigint i = K+1; i < N; i++)
		H.at(i).at(0) = bit(0);

	// find first 1 of the first row, swap columns

	vector<bit> row(0);	

	for (bigint i = 0; i < K; i++)
		row.push_back(H.at(i).at(0));

	vector<bit> idx = bit_vector_first_one(row);

	H.at(K) = ram_read_write(H, 0, K, idx, H.at(K));
	map.at(K) = ram_read_write(map, 0, K, idx, map.at(K));

	// conditionally add the first row to other rows

	for (bigint j = 1; j < R; j++)
		s.at(j) ^= s.at(0) & H.at(K).at(j);

	for (bigint i = 0; i < K; i++)
	for (bigint j = 1; j < R; j++)
		H.at(i).at(j) ^= H.at(i).at(0) & H.at(K).at(j);

	for (bigint j = 1; j < R; j++)
		H.at(K).at(j) = bit(0);

	return H.at(K).at(0);
}