desprocess.cpp

rsa加密算法的vc实现

//the implementation of the DESProcess class

//construct and desconstruct of the DESProcess
DESProcess::DESProcess()
{
	//give defalute value to every member
	for(int i = 0; i < 8; i++)
		mch[i] = '#';
	for(i = 0; i < 64; i++)
	{
		bits[i] = false;
		key[i] = false;
		constkey[i] = false;
		if(i < 48)
			tkey[i] = false;
	}
	right = left = 0;
}

DESProcess::~DESProcess()
{
}

void DESProcess::setBits(const unsigned int& r, const unsigned int& l)
{
	right = r;
	left = l;
}
void DESProcess::setKey(const unsigned int& r, const unsigned int& l)
{
	right = r;
	left = l;
	intToBit();
	for(int i = 0; i < 64; ++i)
		constkey[i] = bits[i];
	
}
void DESProcess::desEnCode()
{
	intToBit();
	desCoding(true);
	bitToInt();
}
void DESProcess::desDeCode()
{
	intToBit();
	desCoding(false);
	bitToInt();
}
void DESProcess::outputBits(unsigned int& r, unsigned int& l)
{
	bitToInt();
	r = right;
	l = left;
}
void DESProcess::intToBit()
{
	unsigned int con = 0x80000000; //the power of 2;
	int i; //circle variable;

	for(i = 0; i < 32; ++i)
	{
		if((con & right) != 0)
			bits[i] = true;
		else
			bits[i] = false;
		con >>= 1;
	}

	con = 0x80000000;
	for(; i < 64; ++i)
	{
		if((con & left) != 0)
			bits[i] = true;
		else
			bits[i] = false;
		con >>= 1;
	}
}

void DESProcess::bitToInt()
{
	int i;
	right = 0;
	for(i = 0; i < 32; ++i)
	{
		right <<= 1;
		if(bits[i])
			right += 1;
	}
	left = 0;
	for(; i < 64; ++i)
	{
		left <<= 1;
		if(bits[i])
			left += 1;
	}
}

//descoding process
void DESProcess::desCoding(bool enCoding)
{
	ipBits();

	int i;//cicle variable
	for(i = 0; i < 64; ++i)
		key[i] = constkey[i];
	pc_1Key();
	int sum = 0;
	for(i = 0; i < 16; ++i)
		sum += ls[i];
	if(! enCoding)
		lsKey(sum);
	else
		lsKey(ls[0]);
	for(i = 0; i < 16; ++i)
	{
		BitsToKey();
		pc_2Key();
		sBoxKey();
		pKey();
		
		DiffBits();
		if(i < 15)
		{
			if(enCoding)
				lsKey(ls[i + 1]);
			else
				lsKey(0 - ls[15 - i]);
			reverseBits();
		}
	}

	fpBits();
}

//IP Permute
void DESProcess::ipBits()
{
	bool temp[64];
	for(int i = 0; i < 64; ++i)
		temp[i] = bits[i];
	for(i = 0; i < 64; ++i)
		bits[i] = temp[ip[i] - 1];
}
//exchange the front and tail
void DESProcess::reverseBits()
{
	bool temp[32];
	for(int i = 0; i < 32; ++i)
	{
		temp[i] = bits[i];
		bits[i] = bits[32 + i];
		bits[32 + i] = temp[i];
	}
}
//Bits and tkey different or
void DESProcess::DiffBits()
{
	for(int i = 0; i < 32; ++i)
		bits[i] = ( (! bits[i]) && tkey[i]) || ( (! tkey[i]) && bits[i]);
}
//ip's contradictory permulate
void DESProcess::fpBits()
{
	bool temp[64];
	for(int i = 0; i < 64; ++i)
		temp[i] = bits[i];
	for(i = 0; i < 64; ++i)
		bits[i] = temp[fp[i] - 1];
}
//pc-1 permulate
void DESProcess::pc_1Key()
{
	bool temp[64];
	for(int i = 0; i < 64; ++i)
		temp[i] = key[i];
	for(i = 0; i < 56; ++i)
		key[i] = temp[pc1[i] - 1];
}
//left shift the key with parameter length
void DESProcess::lsKey(int length)
{
	bool temp[28];
	int i;//circle variable
	length = length + 28;

	for(i = 0; i < 28; ++i)
		temp[i] = key[i];
	for(i = 0; i < 28; ++i)
		key[i] = temp[(i + length) % 28];
	
	for(i = 0; i < 28; ++i)
		temp[i] = key[28 + i];
	for(i = 0; i < 28; ++i)
		key[28 + i] = temp[(i + length) % 28];
}
//expand the right part to the tkey
void DESProcess::BitsToKey()
{
	for(int i = 0; i < 48; ++i)
		tkey[i] = bits[31 + e[i]];
}
//pc_2 permulate and different or
void DESProcess::pc_2Key()
{
	for(int i = 0; i < 48; ++i)
		tkey[i] = ((! tkey[i]) && key[pc2[i] - 1]) || ((! key[pc2[i] - 1]) && tkey[i]);
}
//sBox permulate the key
void DESProcess::sBoxKey()
{
	const int pow_2[4] = {1, 2, 4, 8};
	int i,j;

	bool temp[48];
	for(i = 0; i < 48; ++i)
		temp[i] = tkey[i];

	int tempint;
	for(i = 0; i < 8; ++i)
	{
		tempint = 0;
		for(j = 0; j < 4; ++j)
			if(temp[i * 6 + 4 - j])
				tempint += pow_2[j];
		if(temp[i * 6 + 5])
			tempint += 16;
		if(temp[i*6])
			tempint += 32;
		tempint = sbox[i][tempint];
		for(j = 0; j < 4; ++j)  //number change to tkey
			tkey[i * 4 + j] = ((tempint & pow_2[3 - j]) != 0);
	} //end of for{}
}

//p permulate
void DESProcess::pKey()
{
	bool temp[32];
	for(int i = 0; i < 32; ++i)
		temp[i] = tkey[i];
	for(i = 0; i < 32; ++i)
		tkey[i] = temp[ p[i] - 1];
}