方法一：

    //须添加对System.Web的引用

    using System.Web.Security;

     

    ...

     

    /// <summary>

    /// SHA1加密字符串

    /// </summary>

    /// <param name="source">源字符串</param>

    /// <returns>加密后的字符串</returns>

    public string SHA1(string source)

    {

        return FormsAuthentication.HashPasswordForStoringInConfigFile(source, "SHA1");

    }

 

 

    /// <summary>

    /// MD5加密字符串

    /// </summary>

    /// <param name="source">源字符串</param>

    /// <returns>加密后的字符串</returns>

    public string MD5(string source)

    {

        return FormsAuthentication.HashPasswordForStoringInConfigFile(source, "MD5");;

    }

 

方法五：

    using System.IO;

    using System.Security.Cryptography;

    using System.Text;

     

    ...

     

    //默认密钥向量

    private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

    /// <summary>

    /// DES加密字符串

    /// </summary>

    /// <param name="encryptString">待加密的字符串</param>

    /// <param name="encryptKey">加密密钥,要求为8位</param>

    /// <returns>加密成功返回加密后的字符串，失败返回源串</returns>

    public static string EncryptDES(string encryptString, string encryptKey)

    {

        try

        {

            byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));

            byte[] rgbIV = Keys;

            byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);

            DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();

            MemoryStream mStream = new MemoryStream();

            CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);

            cStream.Write(inputByteArray, 0, inputByteArray.Length);

            cStream.FlushFinalBlock();

            return Convert.ToBase64String(mStream.ToArray());

        }

        catch

        {

            return encryptString;

        }

    }

     

    /// <summary>

    /// DES解密字符串

    /// </summary>

    /// <param name="decryptString">待解密的字符串</param>

    /// <param name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param>

    /// <returns>解密成功返回解密后的字符串，失败返源串</returns>

    public static string DecryptDES(string decryptString, string decryptKey)

    {

        try

        {

            byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey);

            byte[] rgbIV = Keys;

            byte[] inputByteArray = Convert.FromBase64String(decryptString);

            DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();

            MemoryStream mStream = new MemoryStream();

            CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);

            cStream.Write(inputByteArray, 0, inputByteArray.Length);

            cStream.FlushFinalBlock();

            return Encoding.UTF8.GetString(mStream.ToArray());

        }

        catch

        {

            return decryptString;

        }

    }

 

 

 

方法六(文件加密)：

    using System.IO;

    using System.Security.Cryptography;

    using System.Text;

     

    ...

     

    //加密文件

    private static void EncryptData(String inName, String outName, byte[] desKey, byte[] desIV)

    {

        //Create the file streams to handle the input and output files.

        FileStream fin = new FileStream(inName, FileMode.Open, FileAccess.Read);

        FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);

        fout.SetLength(0);

     

        //Create variables to help with read and write.

        byte[] bin = new byte[100]; //This is intermediate storage for the encryption.

        long rdlen = 0;              //This is the total number of bytes written.

        long totlen = fin.Length;    //This is the total length of the input file.

        int len;                     //This is the number of bytes to be written at a time.

     

        DES des = new DESCryptoServiceProvider();

        CryptoStream encStream = new CryptoStream(fout, des.CreateEncryptor(desKey, desIV), CryptoStreamMode.Write);

     

        //Read from the input file, then encrypt and write to the output file.

        while (rdlen < totlen)

        {

            len = fin.Read(bin, 0, 100);

            encStream.Write(bin, 0, len);

            rdlen = rdlen + len;

        }

     

        encStream.Close();

        fout.Close();

        fin.Close();

    }

     

    //解密文件

    private static void DecryptData(String inName, String outName, byte[] desKey, byte[] desIV)

    {

        //Create the file streams to handle the input and output files.

        FileStream fin = new FileStream(inName, FileMode.Open, FileAccess.Read);

        FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);

        fout.SetLength(0);

     

        //Create variables to help with read and write.

        byte[] bin = new byte[100]; //This is intermediate storage for the encryption.

        long rdlen = 0;              //This is the total number of bytes written.

        long totlen = fin.Length;    //This is the total length of the input file.

        int len;                     //This is the number of bytes to be written at a time.

     

        DES des = new DESCryptoServiceProvider();

        CryptoStream encStream = new CryptoStream(fout, des.CreateDecryptor(desKey, desIV), CryptoStreamMode.Write);

     

        //Read from the input file, then encrypt and write to the output file.

        while (rdlen < totlen)

        {

            len = fin.Read(bin, 0, 100);

            encStream.Write(bin, 0, len);

            rdlen = rdlen + len;

        }

     

        encStream.Close();

        fout.Close();

        fin.Close();

 

}

 

原文地址：http://www.cnblogs.com/zengxiangzhan/archive/2010/01/30/1659687.html