Thread: xor Encryption

I am trying to work out the encryption function to the following decryption function.

Code:

char* buf;
	unsigned int nKey = buf[3] << 24;
	nKey |= buf[2] << 16;
	nKey |= buf[1] << 8;
	nKey |= buf[0];
	unsigned int nIndex = 4;

	for(unsigned int nBitNr = 0; nBitNr < 32; ++nBitNr, nIndex++)
	{
		int nDecryptBit = (nKey & (1 << nBitNr)) >> nBitNr;
		int chEncryptedByte = buf[nIndex];
		int chDecryptedByte = chEncryptedByte;

		chDecryptedByte = chDecryptedByte ^ nDecryptBit;
		chDecryptedByte = chDecryptedByte & 1;
		chDecryptedByte = chDecryptedByte ^ chEncryptedByte;
		buf[nIndex] = chDecryptedByte;
		if(nBitNr == 31)
			break;
	}
	printf("File Decrypted is %s\n",buf);

I see that the decrpt key is the first for bytes of Buf and that only 32 bytes are decrypted.

From searching these forums I now know that
a = b ^ c goes to c = b ^ a

would a = b & 1 go to a = b & 0?

also what is this doing?

Code:

int nDecryptBit = (nKey & (1 << nBitNr)) >> nBitNr;