Create XTEA.cpp

src/XTEA.cpp

@@ -0,0 +1,117 @@
+#include <iostream>
+#include <fstream>
+#include <stdint.h>
+
+using namespace std;
+
+#define BLOCK_SIZE 8 //XTEA uses 64-bit blocks, 64 bits is 8 bytes
+
+unsigned int key[4] = { 0xFACE, 0xDEAD, 0xBABE, 0xD00D };
+
+//XTEA block cipher - code from Wikipedia
+//https://en.wikipedia.org/wiki/XTEA
+
+void encipher(unsigned int num_rounds, uint32_t v[2], uint32_t const key[4]) 
+{
+	unsigned int i;
+	uint32_t v0 = v[0], v1 = v[1], sum = 0, delta = 0x9E3779B9;
+	for (i = 0; i < num_rounds; i++) 
+	{
+		v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
+		sum += delta;
+		v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum >> 11) & 3]);
+	}
+	v[0] = v0; v[1] = v1;
+}
+
+void decipher(unsigned int num_rounds, uint32_t v[2], uint32_t const key[4])
+{
+	unsigned int i;
+	uint32_t v0 = v[0], v1 = v[1], delta = 0x9E3779B9, sum = delta * num_rounds;
+	for (i = 0; i < num_rounds; i++)
+	{
+		v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum >> 11) & 3]);
+		sum -= delta;
+		v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
+	}
+	v[0] = v0; v[1] = v1;
+}
+
+void xtea(char filePath[], bool boolEncrypt) {
+
+	//Open file
+	fstream file(filePath, ios::in | ios::out | ios::binary);
+	cout << endl << "Opening file: " << filePath << endl;
+	if (!file) //Check if file is correctly opened
+	{
+		cout << "File " << filePath << " cannot be opened" << endl; 
+		return;
+	}
+
+	cout << "File open" << endl;
+	file.seekg(0, ios::end);
+	unsigned fileSize = file.tellg(); //Get file size
+	cout << "File size: " << fileSize << " bytes" << endl;
+	file.seekg(ios::beg);
+	file.clear();
+
+	//Calculate number of blocks to be encrypted/decrypted
+	int blockNumber = fileSize / BLOCK_SIZE;
+	if (fileSize % BLOCK_SIZE != 0) { ++blockNumber; }
+	cout << "Number of blocks: " << blockNumber << endl;
+
+	//Decalre data array for file operations
+	unsigned char dataArray[BLOCK_SIZE];
+	unsigned filePosition = file.tellg();
+
+	if (boolEncrypt) { cout << "Starting encryption" << endl; }
+	else { cout << "Starting decryption" << endl; }
+	for (int i = 0; i < blockNumber; i++)
+	{
+		//Get data from file
+		file.seekg(filePosition);
+		file.read((char*)dataArray, BLOCK_SIZE);
+
+		//Encrypt/decrypt
+		if (boolEncrypt) { encipher(32, (uint32_t*)dataArray, key); }
+		else { decipher(32, (uint32_t*)dataArray, key); }
+
+		//Write to file
+		file.seekp(filePosition);
+		file.write((char*)dataArray, BLOCK_SIZE);
+
+		//Zero out the data array and increase the pos counter
+		memset(dataArray, 0, BLOCK_SIZE);
+		filePosition += BLOCK_SIZE;
+	}
+	//Close file
+	file.close();
+	cout << "Closing file" << endl;
+	if (boolEncrypt) { cout << "File " << filePath << " has been encrypted" << endl; }
+	else { cout << "File " << filePath << " has been decrypted" << endl; }
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc != 3) 
+	{
+		if ((argc == 2) && (string(argv[1]) == "-h"))
+		{
+			cout << endl << "Usage: " << "[" << argv[0] << "]" << " [file] [-e/-d]" << endl;
+			cout << "[file] is path to the file you want to encrypt/decrypt" << endl;
+			cout << "[-e/-d] choose one to encrypt/decrypt" << endl;
+			cout << endl << "Example usage: XTEA.exe photo.jpg -e" << endl;
+		}
+		else { cout << endl << argv[0] << " You have entered invalid number of parameters" << endl; }
+		return 1;
+	}
+
+	bool encrypt = false;
+	if ((string(argv[2]) != "-e") && ((string(argv[2]) != "-d"))) { cout << "Invalid parameter " << argv[2] << endl; return 1; }
+	if (string(argv[2]) == "-e") { encrypt = true; }
+
+	//Encrypt/decrypt
+	xtea(argv[1], encrypt);
+	return 0;
+}
+