symmetricmethod.cs

C#语言编写的加密、解密小实例

using System;
using System.Data;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace Encrypt
{
	/// <summary>
	/// SymmetricMethod 的摘要说明。
	/// 加密类
	/// 刘兴苗
	/// 2004-11-26
	/// </summary>

	public class SymmetricMethod
	{
		private SymmetricAlgorithm mobjCryptoService;
		private string Key;

		/// <summary>
		/// 对称加密类的构造函数
		/// </summary>
		public SymmetricMethod()
		{
			mobjCryptoService = new RijndaelManaged();
			Key = "Guz(%&hj7x89H$yuBI0456FtmaT5&fvHUFCy76*h%(HilJ$lhj!y6&(*jkP87jH7";
		}

		/// <summary>
		/// 获得密钥
		/// </summary>
		/// <returns>密钥</returns>
		private byte[] GetLegalKey()
		{
			string sTemp = Key;
			mobjCryptoService.GenerateKey();
			byte[] bytTemp = mobjCryptoService.Key;
			int KeyLength = bytTemp.Length;
			if (sTemp.Length > KeyLength)
				sTemp = sTemp.Substring(0, KeyLength);
			else if (sTemp.Length < KeyLength)
				sTemp = sTemp.PadRight(KeyLength, ' ');
			return ASCIIEncoding.ASCII.GetBytes(sTemp);
		}

		/// <summary>
		/// 获得初始向量IV
		/// </summary>
		/// <returns>初试向量IV</returns>
		private byte[] GetLegalIV()
		{
			string sTemp = "E4ghj*Ghg7!rNIfb&95GUY86GfghUb#er57HBh(u%g6HJ($jhWk7&!hg4ui%$hjk";
			mobjCryptoService.GenerateIV();
			byte[] bytTemp = mobjCryptoService.IV;
			int IVLength = bytTemp.Length;
			if (sTemp.Length > IVLength)
				sTemp = sTemp.Substring(0, IVLength);
			else if (sTemp.Length < IVLength)
				sTemp = sTemp.PadRight(IVLength, ' ');
			return ASCIIEncoding.ASCII.GetBytes(sTemp);
		}

		/// <summary>
		/// 加密方法
		/// </summary>
		/// <param name="Source">待加密的串</param>
		/// <returns>经过加密的串</returns>
		public string Encrypto(string Source)
		{
			byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
			MemoryStream ms = new MemoryStream();
			mobjCryptoService.Key = GetLegalKey();
			mobjCryptoService.IV = GetLegalIV();
			ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
			CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
			cs.Write(bytIn, 0, bytIn.Length);
			cs.FlushFinalBlock();
			ms.Close();
			byte[] bytOut = ms.ToArray();
			return Convert.ToBase64String(bytOut);
		}

		/// <summary>
		/// 解密方法
		/// </summary>
		/// <param name="Source">待解密的串</param>
		/// <returns>经过解密的串</returns>
		public string Decrypto(string Source)
		{
			byte[] bytIn = Convert.FromBase64String(Source);
			MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
			mobjCryptoService.Key = GetLegalKey();
			mobjCryptoService.IV = GetLegalIV();
			ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
			CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
			StreamReader sr = new StreamReader(cs);
			return sr.ReadToEnd();
		}
	}
}