c# 加密与解密

using System.Security.Cryptography;
using System.IO;

namespace Common
{
/**//// <summary>
/// DESEncrypt加密解密算法。
/// </summary>
public sealed class DESEncrypt
{
private DESEncrypt()
{
//
// TODO: 在此处添加构造函数逻辑
//
}

private static string key = "zhoufoxcn";

/**//// <summary>
/// 对称加密解密的密钥
/// </summary>
public static string Key
{
get
{
return key;
}
set
{
key = value;
}
}

/**//// <summary>
/// DES加密
/// </summary>
/// <param name="encryptString"></param>
/// <returns></returns>
public static string DesEncrypt(string encryptString)
{
byte[] keyBytes = Encoding.UTF8.GetBytes(key.Substring(0, 8));
byte[] keyIV = keyBytes;
byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
MemoryStream mStream = new MemoryStream();
CryptoStream cStream = new CryptoStream(mStream, provider.CreateEncryptor(keyBytes, keyIV), CryptoStreamMode.Write);
cStream.Write(inputByteArray, 0, inputByteArray.Length);
cStream.FlushFinalBlock();
return Convert.ToBase64String(mStream.ToArray());
}

/**//// <summary>
/// DES解密
/// </summary>
/// <param name="decryptString"></param>
/// <returns></returns>
public static string DesDecrypt(string decryptString)
{
byte[] keyBytes = Encoding.UTF8.GetBytes(key.Substring(0, 8));
byte[] keyIV = keyBytes;
byte[] inputByteArray = Convert.FromBase64String(decryptString);
DESCryptoServiceProvider provider = new DESCryptoServiceProvider();
MemoryStream mStream = new MemoryStream();
CryptoStream cStream = new CryptoStream(mStream, provider.CreateDecryptor(keyBytes, keyIV), CryptoStreamMode.Write);
cStream.Write(inputByteArray, 0, inputByteArray.Length);
cStream.FlushFinalBlock();
return Encoding.UTF8.GetString(mStream.ToArray());
}
}

/// <summary>
/// 一个实现MD5散列字符串的类
/// 作者：周公
/// 日期：2007
/// </summary>
public sealed class MD5Hashing
{
private static MD5 md5 = MD5.Create();
//私有化构造函数
private MD5Hashing()
{
}
/// <summary>
/// 使用utf8编码将字符串散列
/// </summary>
/// <param name="sourceString">要散列的字符串</param>
/// <returns>散列后的字符串</returns>
public static string HashString(string sourceString)
{
return HashString(Encoding.UTF8, sourceString);
}
/// <summary>
/// 使用指定的编码将字符串散列
/// </summary>
/// <param name="encode">编码</param>
/// <param name="sourceString">要散列的字符串</param>
/// <returns>散列后的字符串</returns>
public static string HashString(Encoding encode, string sourceString)
{
byte[] source = md5.ComputeHash(encode.GetBytes(sourceString));
StringBuilder sBuilder = new StringBuilder();
for (int i = 0; i < source.Length; i++)
{
sBuilder.Append(source[i].ToString("x2"));
}
return sBuilder.ToString();
}
}

/// <summary>
/// 实现Base64加密解密
/// 作者：周公
/// 时间：2007
/// </summary>
public sealed class Base64
{
/// <summary>
/// Base64加密
/// </summary>
/// <param name="codeName">加密采用的编码方式</param>
/// <param name="source">待加密的明文</param>
/// <returns></returns>
public static string EncodeBase64(Encoding encode, string source)
{
byte[] bytes = encode.GetBytes(source);
string str;
try
{
str = Convert.ToBase64String(bytes);//Convert.ToBase64String(bytes);
}
catch
{
str = source; //encode = source;
}
return str;       //return encode
}

/// <summary>
/// Base64加密，采用utf8编码方式加密
/// </summary>
/// <param name="source">待加密的明文</param>
/// <returns>加密后的字符串</returns>
public static string EncodeBase64(string source)
{
return EncodeBase64(Encoding.UTF8, source);
}

/// <summary>
/// Base64解密
/// </summary>
/// <param name="codeName">解密采用的编码方式，注意和加密时采用的方式一致</param>
/// <param name="result">待解密的密文</param>
/// <returns>解密后的字符串</returns>
public static string DecodeBase64(Encoding encode, string result)
{
string decode = "";
byte[] bytes = Convert.FromBase64String(result);
try
{
decode = encode.GetString(bytes);
}
catch
{
decode = result;
}
return decode;
}

/// <summary>
/// Base64解密，采用utf8编码方式解密
/// </summary>
/// <param name="result">待解密的密文</param>
/// <returns>解密后的字符串</returns>
public static string DecodeBase64(string result)
{
return DecodeBase64(Encoding.UTF8, result);
}
}