tea2.cpp

tea 加密算法 qq使用的就是这个加密算法来 解决登陆问题

public class Tea
{
	public static byte[] Encrypt(byte[] data, byte[] key) 
	{
		byte[] dataBytes;
		if (data.Length % 2 == 0)
		{
			dataBytes = data;
		} 
		else 
		{
			dataBytes = new byte[data.Length + 1];
			Array.Copy(data,0,dataBytes,0,data.Length);
			dataBytes[data.Length] = 0x0;
		}

		byte[] result = new byte[dataBytes.Length * 4];
		uint[] formattedKey = FormatKey(key);
		uint[] tempData = new uint[2];
		for (int i = 0; i < dataBytes.Length; i += 2) {
			tempData[0] = dataBytes[i];
			tempData[1] = dataBytes[i + 1];
			code(tempData, formattedKey);
			Array.Copy(ConvertUIntToByteArray(tempData[0]),0,result,i * 4,4);
			Array.Copy(ConvertUIntToByteArray(tempData[1]),0,result,i*4+4,4);
		}
		return result;
	}

	public static byte[] Decrypt(byte[] data, byte[] key) {
		uint[] formattedKey = FormatKey(key);
		int x = 0;
		uint[] tempData = new uint[2];
		byte[] dataBytes = new byte[data.Length / 8 * 2];
		
		for (int i = 0; i < data.Length; i += 8) {
			tempData[0] = ConvertByteArrayToUInt(data, i);
			tempData[1] = ConvertByteArrayToUInt(data, i + 4);
			decode(tempData, formattedKey);
			dataBytes[x++] = (byte)tempData[0];
			dataBytes[x++] = (byte)tempData[1];
		}

		//修剪添加的空字符
		if (dataBytes[dataBytes.Length - 1] == 0x0) {
			byte[] result = new byte[dataBytes.Length - 1];
			Array.Copy(dataBytes,0,result,0,dataBytes.Length - 1);
		}

		return dataBytes;
	}

	static uint[] FormatKey(byte[] key) 
	{
		if (key.Length == 0)
			throw new ArgumentException("Key must be between 1 and 16 characters in length");
		byte[] refineKey =new byte[16];
		
		if (key.Length < 16) 
		{
			Array.Copy(key, 0, refineKey, 0, key.Length);
			for (int k = key.Length; k < 16; k++) {
				refineKey[k] = 0x20;
			}
		} 
		else 
		{
			Array.Copy(key,0,refineKey,0,16);
		}
		
		uint[] formattedKey = new uint[4];
		int j = 0;
		for (int i = 0; i < refineKey.Length; i += 4)
			formattedKey[j++] = ConvertByteArrayToUInt(refineKey, i);
		
		return formattedKey;
	}

#region Tea Algorithm
	static void code(uint[] v, uint[] k) 
	{
		uint y = v[0];
		uint z = v[1];
		uint sum = 0;
		uint delta = 0x9e3779b9;
		uint n = 16;
		while (n-- > 0) 
		{
			sum += delta;
			y += (z << 4) + k[0] ^ z + sum ^ (z >> 5) + k[1];
			z += (y << 4) + k[2] ^ y + sum ^ (y >> 5) + k[3];
		}
		
		v[0] = y;
		v[1] = z;
	}
	static void decode(uint[] v, uint[] k) 
	{
		uint n = 16;
		uint sum;
		uint y = v[0];
		uint z = v[1];
		uint delta = 0x9e3779b9;
		/*
		* 由于进行16轮运算，所以将delta左移4位，减16次后刚好为0.
		*/
		
		sum = delta << 4;
		while (n-- > 0) 
		{
			z -= (y << 4) + k[2] ^ y + sum ^ (y >> 5) + k[3];
			y -= (z << 4) + k[0] ^ z + sum ^ (z >> 5) + k[1];
			sum -= delta;
		}
		
		v[0] = y;
		v[1] = z;
	}
#endregion
	
	private static byte[] ConvertUIntToByteArray(uint v) 
	{
		byte[] result = new byte[4];
		result[0] = (byte)(v & 0xFF);
		result[1] = (byte)((v >> 8) & 0xFF);
		result[2] = (byte)((v >> 16) & 0xFF);
		result[3] = (byte)((v >> 24) & 0xFF);
		return result;
	}
	private static uint ConvertByteArrayToUInt(byte[] v, int offset) {
		if (offset + 4 > v.Length) return 0;
		uint output;
		output = (uint)v[offset];
		output |= (uint)(v[offset + 1] << 8);
		output |= (uint)(v[offset + 2] << 16);
		output |= (uint)(v[offset + 3] << 24);
		return output;
	}

}