tea.cs

tea算法的实现,可以进行普通加密解密

using System;


namespace TeaCrypto
{
	/// <summary>
	/// Summary description for Tea.
	/// </summary>
	public class Tea
	{
		// Ctor
		public Tea()
		{
		}

		public string EncryptString(string Data, string Key)
		{
			if(Data.Length == 0)
				throw new ArgumentException("Data must be at least 1 character in length.");

			uint[] formattedKey = FormatKey(Key);

			if(Data.Length%2!=0) Data += '\0'; // Make sure array is even in length.		
			byte[] dataBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(Data);

			string cipher = string.Empty;
			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);
				cipher += Util.ConvertUIntToString(tempData[0]) + Util.ConvertUIntToString(tempData[1]);
			}
			
			return cipher;
		}

		public string Decrypt(string Data, string 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] = Util.ConvertStringToUInt(Data.Substring(i, 4));
				tempData[1] = Util.ConvertStringToUInt(Data.Substring(i+4, 4));
				decode(tempData, formattedKey);
				dataBytes[x++] = (byte)tempData[0];
				dataBytes[x++] = (byte)tempData[1];
			}

			string decipheredString = System.Text.ASCIIEncoding.ASCII.GetString(dataBytes, 0, dataBytes.Length);
			if(decipheredString[decipheredString.Length - 1] == '\0') // Strip the null char if it was added.
				decipheredString = decipheredString.Substring(0, decipheredString.Length - 1);
			return decipheredString;
		}

		public uint[] FormatKey(string Key)
		{
			if(Key.Length == 0)
				throw new ArgumentException("Key must be between 1 and 16 characters in length");

			Key = Key.PadRight(16,' ').Substring(0, 16); // Ensure that the key is 16 chars in length.
			uint[] formattedKey = new uint[4];

			// Get the key into the correct format for TEA usage.
			int j = 0;
			for(int i=0; i<Key.Length; i+=4)
				formattedKey[j++] = Util.ConvertStringToUInt(Key.Substring(i, 4));

			return formattedKey;
		}

		#region Tea Algorithm
		public void code(uint[] v, uint[] k)  
		{              
			uint y = v[0];
			uint z = v[1];
			uint sum = 0;   
			uint delta=0x9e3779b9;
			uint n=32;             

			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; 
		}

		public void decode(uint[] v, uint[] k)  
		{
			uint n=32;
			uint sum;
			uint y=v[0];
			uint z=v[1];
			uint delta=0x9e3779b9;

			sum = delta << 5 ;

			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
	}
	
}