#ifndef RSA_H
#define RSA_H

#include<fstream>
#include<cstdio>
using namespace std;
#include"BigInt.h"
class rsa{
public:
	rsa();
	~rsa();
	void setkey(const BigInt& prp, const BigInt& prq, const BigInt& pubk);
	void setpubkey(const BigInt& pubk, const BigInt& n);
	void setMFileName(char* rsa_m);
	void setCFileName(char* rsa_c);
	void DeCode(int choose, int base);
	void EnCode(int choose, int base);
private:
	void init();
	void DeCodingProcess(int choose, int base);
	void DeCodingSpecial(int choose, int base);
	void EnCodingProcess(int base);
	void EnCodingSpecial(int base);
	BigInt primeP;
	BigInt primeQ;
	BigInt modn;
	BigInt pubkey;
	BigInt prikey;
	BigInt fp;
	BigInt fq;
	char* rsach;
	char rsacFile[30];
	char rsamFile[30];
	int rsal;
};

rsa::rsa()
{
	primeP = 952559;
	primeQ = 999983;
	pubkey = 11;
	init();
	rsach = NULL;
	strcpy(rsacFile, "c.txt");
	strcpy(rsamFile, "m.txt");
}
rsa::~rsa()
{
	primeP.clear();
	primeQ.clear();
	modn.clear();
	pubkey.clear();
	prikey.clear();
	fp.clear();
	fq.clear();
}

void rsa::init()
{
	modn = primeP * primeQ;
	--primeP;
	--primeQ;
	prikey = primeP * primeQ;
	prikey = pubkey.BIinverse(prikey);
	++primeP;
	++primeQ;
	rsal = modn.nodeNumber();
	rsal *= 32;
	intNode* t = modn.getHead();
	if(TheLastNode(t))
		rsal -= FindZeroBit(t->num);
	fp = primeP.BIinverse(primeQ);
	fq = primeQ.BIinverse(primeP);

}
void rsa::setkey(const BigInt& prp, const BigInt& prq, const BigInt& pubk)
{
	primeP.copy(prp);
	primeQ.copy(prq);
	pubkey.copy(pubk);
	init();
}
void rsa::setpubkey(const BigInt& pubk, const BigInt& n)
{
	pubkey.copy(pubk);
	modn.copy(n);
	rsal = modn.nodeNumber();
	rsal *= 32;
	intNode* t = modn.getHead();
	if(TheLastNode(t))
		rsal -= FindZeroBit(t->num);

}
void rsa::setMFileName(char* rsa_m)
{
	strcpy(rsamFile, rsa_m);
}
void rsa::setCFileName(char* rsa_c)
{
	strcpy(rsacFile, rsa_c);
}
//1. represent number based on decimal.
//2. represent number based on hex.
//3. represent with a = 01, b = 02........... to decimal
void rsa::EnCode(int choose,int base)
{
	switch(choose)
	{
	case 1:
		EnCodingProcess(base);
		break;
	case 2:
		EnCodingSpecial(base);
		break;
	default:
		break;
	}
}
void rsa::DeCode(int choose, int base)
{
	switch(choose)
	{
	case 1:
		DeCodingProcess(choose, base);
		break;
	case 2:
		DeCodingProcess(choose, base);
		break;
	case 3:
		DeCodingSpecial(choose, base);
		break;
	case 4:
		DeCodingSpecial(choose, base);
		break;
	default:
		break;
	}
}

void rsa::EnCodingProcess(int base)
{
	FILE* fp;
	if( (fp = fopen(rsamFile, "r") ) == NULL)
		return;

	fstream out;
	out.open(rsacFile, ios::out);

	int r_length;
	r_length = rsal  / 8;
	rsach = new char[r_length];

	BigInt temp;
	char* rsa_re;
	int rsa_leng;
	int count = 0;
	int i;

	int times = 0;
	while(! feof(fp))
	{
		rsach[count++] = fgetc(fp);
		if(count == r_length)
		{
			++times;
			cout << "第 " << times << " 輪加密!";
			count = 0;
			temp.loadSTR(rsach, r_length);
			temp = BImodexp2(temp, pubkey, modn);
			if(base == 10)
				rsa_re = temp.outputDEC(rsa_leng);
			else
				rsa_re = temp.outputHEX(rsa_leng);
			for(i = 0; i < rsa_leng; ++i)
				out << rsa_re[i];
			delete[] rsa_re;
			out << endl;
		}
	}
	++times;
	cout << "第 " << times << " 輪加密!";
	temp.loadSTR(rsach, count);
	temp = BImodexp2(temp, pubkey, modn);
	if(base == 10)
		rsa_re = temp.outputDEC(rsa_leng);
	else
		rsa_re = temp.outputHEX(rsa_leng);
	for(i = 0; i < rsa_leng; ++i)
			out << rsa_re[i];
	delete[] rsa_re;

	delete[] rsach;
	temp.clear();
	out.close();
	fclose(fp);
}

void rsa::DeCodingProcess(int choose, int base)
{
	fstream out;
	fstream in;
	in.open(rsacFile, ios::in);
	out.open(rsamFile, ios::out);

	BigInt temp;
	BigInt temp1;
	BigInt temp2;
	int r_length;
	char* rr;
	r_length = rsal * 3  / 10;
	rsach = new char[r_length + 5];

	int times = 0;
	while(in >> rsach)
	{
		++times;
		cout << "第 " << times << " 輪解密!";
		if(base == 10)
			temp.loadDEC(rsach, strlen(rsach));
		else
			temp.loadHEX(rsach, strlen(rsach));
		if(choose == 1)
			temp = BImodexp2(temp, prikey, modn);
		else
		{
			temp1 = BImodexp2(temp, prikey, primeP);
			temp2 = BImodexp2(temp, prikey, primeQ);
			temp1 = temp1 * fq;
			temp1 = temp1 * primeQ;
			temp2 = temp2 * fp;
			temp2 = temp2 * primeP;
			temp = temp1 + temp2;
			temp = temp % modn;
		}
		rr = temp.outputSTR(r_length);
		for(int i = 0; i < r_length; ++i)
			out << rr[i];
		out << endl;
		delete[] rr;
	}

	delete[] rsach;
	temp.clear();
	temp1.clear();
	temp2.clear();
	out.close();
	in.close();
}

void rsa::EnCodingSpecial(int base)
{
	FILE* ffp;
	if( (ffp = fopen(rsamFile, "r") ) == NULL)
		return;

	fstream out;
	out.open(rsacFile, ios::out);

	int r_length;
	r_length = rsal * 3  / 20;

	BigInt temp;
	int rsa_leng;
	int count = 0;
	unsigned int rsa_int;
	char rsa_c;
	int i;
	int times = 0;

	while(! feof(ffp))
	{
		rsa_c = fgetc(ffp);
		if((rsa_c <= 'z' && rsa_c >= 'a') || (rsa_c <= 'Z' && rsa_c >= 'A'))
		{
			++count;
			if(rsa_c <= 'Z' && rsa_c >= 'A')
				rsa_int = ((unsigned int) ( rsa_c - 'A')) + 26;
			else
				rsa_int = ((unsigned int) ( rsa_c - 'a'));
			temp = temp * 100;
			temp += rsa_int;
			if(count == r_length)
			{
				++times;
				cout << "第 " << times << " 輪加密!";
				count = 0;
				temp = BImodexp2(temp, pubkey, modn);
				if(base == 10)
					rsach = temp.outputDEC(rsa_leng);
				else
					rsach = temp.outputHEX(rsa_leng);
				temp.setZero();
				for(i = 0; i < rsa_leng; ++i)
					out << rsach[i];
				delete[] rsach;
				out << endl;
			}
		}
	}
	temp = BImodexp2(temp, pubkey, modn);
	if(base == 10)
		rsach = temp.outputDEC(rsa_leng);
	else
		rsach = temp.outputHEX(rsa_leng);
	for(i = 0; i < rsa_leng; ++i)
			out << rsach[i];
	delete[] rsach;

	temp.clear();
	out.close();
	fclose(ffp);
}
void rsa::DeCodingSpecial(int choose, int base)
{
	fstream out;
	fstream in;
	in.open(rsacFile, ios::in);
	out.open(rsamFile, ios::out);

	BigInt temp;
	BigInt temp1;
	BigInt temp2;
	int r_length;
	char* rr;
	r_length = rsal * 3  / 10;
	rsach = new char[r_length + 5];
	rr = new char[r_length + 5];
	unsigned int rsa_int;
	int count;
	int times = 0;
	while(in >> rsach)
	{
		++times;
		cout << "第 " << times << " 輪解密!";
		if(base == 10)
			temp.loadDEC(rsach, strlen(rsach));
		else
			temp.loadHEX(rsach, strlen(rsach));

		if(choose == 3)
			temp = BImodexp2(temp, prikey, modn);

		else
		{
			temp1 = BImodexp2(temp, prikey, primeP);
			temp2 = BImodexp2(temp, prikey, primeQ);
			temp1 = temp1 * fq;
			temp1 = temp1 * primeQ;
			temp2 = temp2 * fp;
			temp2 = temp2 * primeP;
			temp = temp1 + temp2;
			temp = (temp % modn);
		}   
		count = 0;
		while(! temp.BIlisZero())
		{
			rsa_int = temp % 100;
			temp = temp / 100;
			if(rsa_int >= 0 && rsa_int <= 25)
				rr[count ++] = (char)(rsa_int + ((unsigned int)'a'));
			else if(rsa_int >= 26 && rsa_int <= 51) 
				rr[count ++] = (char)(rsa_int + ((unsigned int)'A') - 26);
		}
		for(int i = 0; i < count; ++i)
			out << rr[count - i - 1];
	}

	delete[] rr;
	delete[] rsach;
	temp.clear();
	temp1.clear();
	temp2.clear();
	out.close();
	in.close();
}

#endif