C#加密与解密

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DES加密解密：//名称空间
using  System;
using  System.Security.Cryptography;
using  System.IO;
using  System.Text;

//方法
//加密方法

//sKey输入密码的时候，必须使用英文字符，区分大小写，且字符数量是8个，不能多也不能少，否则出错。
public    string  Encrypt(string  pToEncrypt,  string  sKey)
{
           DESCryptoServiceProvider  des  =  new  DESCryptoServiceProvider();
           //把字符串放到byte数组中
                 //原来使用的UTF8编码，我改成Unicode编码了，不行
           byte[]  inputByteArray  =  Encoding.Default.GetBytes(pToEncrypt);
           //byte[]  inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt);

           //建立加密对象的密钥和偏移量
           //原文使用ASCIIEncoding.ASCII方法的GetBytes方法
           //使得输入密码必须输入英文文本
           des.Key  =  ASCIIEncoding.ASCII.GetBytes(sKey);
           des.IV  =  ASCIIEncoding.ASCII.GetBytes(sKey);
           MemoryStream  ms  =  new  MemoryStream();
           CryptoStream  cs  =  new  CryptoStream(ms,  des.CreateEncryptor(),CryptoStreamMode.Write);
           //Write  the  byte  array  into  the  crypto  stream
           //(It  will  end  up  in  the  memory  stream)
           cs.Write(inputByteArray,  0,  inputByteArray.Length);
           cs.FlushFinalBlock();
           //Get  the  data  back  from  the  memory  stream,  and  into  a  string
           StringBuilder  ret  =  new  StringBuilder();
           foreach(byte  b  in  ms.ToArray())
                       {
                       //Format  as  hex
                       ret.AppendFormat("{0:X2}",  b);
                       }
           ret.ToString();
           return  ret.ToString();
}

//解密方法
public    string  Decrypt(string  pToDecrypt,  string  sKey)
{
           DESCryptoServiceProvider  des  =  new  DESCryptoServiceProvider();

           //Put  the  input  string  into  the  byte  array
           byte[]  inputByteArray  =  new  byte[pToDecrypt.Length  /  2];
           for(int  x  =  0;  x  <  pToDecrypt.Length  /  2;  x++)
           {
                     int  i  =  (Convert.ToInt32(pToDecrypt.Substring(x  *  2,  2),  16));
               inputByteArray[x]  =  (byte)i;
           }

           //建立加密对象的密钥和偏移量，此值重要，不能修改
           des.Key  =  ASCIIEncoding.ASCII.GetBytes(sKey);
           des.IV  =  ASCIIEncoding.ASCII.GetBytes(sKey);
           MemoryStream  ms  =  new  MemoryStream();
           CryptoStream  cs  =  new  CryptoStream(ms,  des.CreateDecryptor(),CryptoStreamMode.Write);
           //Flush  the  data  through  the  crypto  stream  into  the  memory  stream
           cs.Write(inputByteArray,  0,  inputByteArray.Length);
           cs.FlushFinalBlock();

           //Get  the  decrypted  data  back  from  the  memory  stream
           //建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象
           StringBuilder  ret  =  new  StringBuilder();

           return  System.Text.Encoding.Default.GetString(ms.ToArray());
}

SHA1加密：散列是一种单向算法，一旦数据被转换，将无法再获得其原始值，只能对加密后的数据进行比较

    /// <summary>
    /// SHA1加密，不可逆转
    /// </summary>
    /// <param name="str">string str:被加密的字符串</param>
    /// <returns>返回加密后的字符串</returns>
    private string SHA1Encrypt(string str)
    {
        System.Security.Cryptography.SHA1 s1 = new System.Security.Cryptography.SHA1CryptoServiceProvider();
        byte[] byte1;
        byte1 = s1.ComputeHash(Encoding.Default.GetBytes(str));
        s1.Clear();
        return Convert.ToBase64String(byte1);
    }

    /// <summary>
    /// SHA256加密，不可逆转
    /// </summary>
    /// <param name="str">string str:被加密的字符串</param>
    /// <returns>返回加密后的字符串</returns>
    private string SHA256Encrypt(string str)
    {
        System.Security.Cryptography.SHA256 s256 = new System.Security.Cryptography.SHA256Managed();
        byte[] byte1;
        byte1 = s256.ComputeHash(Encoding.Default.GetBytes(str));
        s256.Clear();
        return Convert.ToBase64String(byte1);
    }

    /// <summary>
    /// SHA384加密，不可逆转
    /// </summary>
    /// <param name="str">string str:被加密的字符串</param>
    /// <returns>返回加密后的字符串</returns>
    private string SHA384Encrypt(string str)
    {
        System.Security.Cryptography.SHA384 s384 = new System.Security.Cryptography.SHA384Managed();
        byte[] byte1;
        byte1 = s384.ComputeHash(Encoding.Default.GetBytes(str));
        s384.Clear();
        return Convert.ToBase64String(byte1);
    }

    /// <summary>
    /// SHA512加密，不可逆转
    /// </summary>
    /// <param name="str">string str:被加密的字符串</param>
    /// <returns>返回加密后的字符串</returns>
    private string SHA512Encrypt(string str)
    {
        System.Security.Cryptography.SHA512 s512 = new System.Security.Cryptography.SHA512Managed();
        byte[] byte1;
        byte1 = s512.ComputeHash(Encoding.Default.GetBytes(str));
        s512.Clear();
        return Convert.ToBase64String(byte1);
    }

    /// <summary>
    /// MD5加密，不可逆转
    /// </summary>
    /// <param name="str">string str:被加密的字符串</param>
    /// <returns>返回加密后的字符串</returns>
    private string MD5Encrypt(string str)
    {
        System.Security.Cryptography.MD5 m5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
        byte[] byte1;
        byte1 = m5.ComputeHash(Encoding.Default.GetBytes(str));
        m5.Clear();
        return Convert.ToBase64String(byte1);
    }