类实现.NET框架下的加密和解密

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System;
using System.Security.Cryptography;
using System.IO;
using System.Text;

/// <summary>
/// Security 的摘要说明
/// Security类实现.NET框架下的加密和解密。
/// </summary>
namespace PTFair.WebSites.Common
{
    public class Security
    {
        string _QueryStringKey = ConfigurationSettings.AppSettings["CryptionKey"]; //URL传输参数加密Key
        string _PassWordKey = "hgfedcba";//PassWord加密Key
        public Security()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //
        }

        ///
        /// 加密URL传输的字符串
        ///
        public string EncryptQueryString(string QueryString)
        {
            return Encrypt(QueryString, _QueryStringKey);
        }

        ///
        /// 解密URL传输的字符串
        ///
        public string DecryptQueryString(string QueryString)
        {
            return Decrypt(QueryString, _QueryStringKey);
        }

        ///
        /// 加密帐号口令
        ///
        public string EncryptPassWord(string PassWord)
        {
            return Encrypt(PassWord, _PassWordKey);
        }

        ///
        /// 解密帐号口令
        ///
        public string DecryptPassWord(string PassWord)
        {
            return Decrypt(PassWord, _PassWordKey);
        }

        ///
        /// DEC 加密过程
        ///
        public string Encrypt(string pToEncrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();//把字符串放到byte数组中

            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
            //byte[]inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt);
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);//建立加密对象的密钥和偏移量
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey); //原文使用ASCIIEncoding.ASCII方法的GetBytes方法
            MemoryStream ms = new MemoryStream(); //使得输入密码必须输入英文文本
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }

            ret.ToString();
            return ret.ToString();
        }

        ///
        /// DEC 解密过程
        ///
        public string Decrypt(string pToDecrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            int len = pToDecrypt.Length / 2;
            byte[] inputByteArray = new byte[len];
            for (int x = 0; x < len; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);//建立加密对象的密钥和偏移量,此值重要,不能修改
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();//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
            return System.Text.Encoding.Default.GetString(ms.ToArray());
        }

        ///
        /// 检查己加密的字符串是否与原文相同
        ///
        public bool ValidateString(string EnString, string FoString, int Mode)
        {
            switch (Mode)
            {
                default:
                case 1:
                    if (Decrypt(EnString, _QueryStringKey) == FoString.ToString())
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                case 2:
                    if (Decrypt(EnString, _PassWordKey) == FoString.ToString())
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
            }
        }
    }
}