[C#] 常用工具类——加密解密类

using System;
using System.Configuration;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.Security;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.IO;
using System.Security.Cryptography;

namespace Utils
{
    /// <summary>
    /// <para>　</para>
    /// 　常用工具类——加密解密类
    /// <para>　-------------------------------------------------</para>
    /// <para>　StringEncode：返回 HTML 字符串的编码结果</para>
    /// <para>　StringDecode：返回 HTML 字符串的解码结果</para>
    /// <para>　UrlEncode：返回 URL 字符串的编码结果</para>
    /// <para>　UrlDecode：返回 URL 字符串的解码结果</para>
    /// <para>　DESEncrypt：DES加密</para>
    /// <para>　DESDecrypt：DES解密</para>
    /// <para>　MD5：MD5函数</para>
    /// <para>　SHA256：SHA256函数</para>
    /// </summary>
    public class EncyptHelper
    {
        /// <summary>
        /// 32位Key值：
        /// </summary>
        public static byte[] DESKey = new byte[] { 0x03, 0x0B, 0x13, 0x1B, 0x23, 0x2B, 0x33, 0x3B, 0x43, 0x4B, 0x9B, 0x93, 0x8B, 0x83, 0x7B, 0x73, 0x6B, 0x63, 0x5B, 0x53, 0xF3, 0xFB, 0xA3, 0xAB, 0xB3, 0xBB, 0xC3, 0xEB, 0xE3, 0xDB, 0xD3, 0xCB };

        #region 返回 HTML 字符串的编码结果
        /// <summary>
        /// 返回 HTML 字符串的编码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>编码结果</returns>
        public static string StringEncode(string str)
        {
            return HttpUtility.HtmlEncode(str);
        }
        #endregion

        #region 返回 HTML 字符串的解码结果
        /// <summary>
        /// 返回 HTML 字符串的解码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>解码结果</returns>
        public static string StringDecode(string str)
        {
            return HttpUtility.HtmlDecode(str);
        }
        #endregion

        #region 返回 URL 字符串的编码结果
        /// <summary>
        /// 返回 URL 字符串的编码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>编码结果</returns>
        public static string UrlEncode(string str)
        {
            return HttpUtility.UrlEncode(str);
        }
        #endregion

        #region 返回 URL 字符串的解码结果
        /// <summary>
        /// 返回 URL 字符串的解码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>解码结果</returns>
        public static string UrlDecode(string str)
        {
            return HttpUtility.UrlDecode(str);
        }
        #endregion

        #region DES加密
        /// <summary>
        /// DES加密
        /// </summary>
        /// <param name="strSource">待加密字串</param>
        /// <returns>加密后的字符串</returns>
        public static string DESEncrypt(string strSource)
        {
            return DESEncrypt(strSource, DESKey);
        }
        /// <summary>
        /// DES加密
        /// </summary>
        /// <param name="strSource">待加密字串</param>
        /// <param name="key">Key值</param>
        /// <returns>加密后的字符串</returns>
        public static string DESEncrypt(string strSource, byte[] key)
        {
            SymmetricAlgorithm sa = Rijndael.Create();
            sa.Key = key;
            sa.Mode = CipherMode.ECB;
            sa.Padding = PaddingMode.Zeros;
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, sa.CreateEncryptor(), CryptoStreamMode.Write);
            byte[] byt = Encoding.Unicode.GetBytes(strSource);
            cs.Write(byt, 0, byt.Length);
            cs.FlushFinalBlock();
            cs.Close();
            return Convert.ToBase64String(ms.ToArray());
        }
        #endregion

        #region DES解密
        /// <summary>
        /// DES解密
        /// </summary>
        /// <param name="strSource">待解密的字串</param>
        /// <returns>解密后的字符串</returns>
        public static string DESDecrypt(string strSource)
        {
            return DESDecrypt(strSource, DESKey);
        }
        /// <summary>
        /// DES解密
        /// </summary>
        /// <param name="strSource">待解密的字串</param>
        /// <param name="key">32位Key值</param>
        /// <returns>解密后的字符串</returns>
        public static string DESDecrypt(string strSource, byte[] key)
        {
            SymmetricAlgorithm sa = Rijndael.Create();
            sa.Key = key;
            sa.Mode = CipherMode.ECB;
            sa.Padding = PaddingMode.Zeros;
            ICryptoTransform ct = sa.CreateDecryptor();
            byte[] byt = Convert.FromBase64String(strSource);
            MemoryStream ms = new MemoryStream(byt);
            CryptoStream cs = new CryptoStream(ms, ct, CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(cs, Encoding.Unicode);
            return sr.ReadToEnd();
        }
        #endregion        

        #region MD5函数
        /// <summary>
        /// MD5函数,需引用：using System.Security.Cryptography;
        /// </summary>
        /// <param name="str">原始字符串</param>
        /// <returns>MD5结果</returns>
        public static string MD5(string str)
        {
            byte[] b = Encoding.Default.GetBytes(str);
            b = new MD5CryptoServiceProvider().ComputeHash(b);
            string ret = "";
            for (int i = 0; i < b.Length; i++)
                ret += b[i].ToString("x").PadLeft(2, '0');
            return ret;
        }
        #endregion

        #region SHA256函数
        /// <summary>
        /// SHA256函数
        /// </summary>
        /// /// <param name="str">原始字符串</param>
        /// <returns>SHA256结果</returns>
        public static string SHA256(string str)
        {
            byte[] SHA256Data = Encoding.UTF8.GetBytes(str);
            SHA256Managed Sha256 = new SHA256Managed();
            byte[] Result = Sha256.ComputeHash(SHA256Data);
            return Convert.ToBase64String(Result);  //返回长度为44字节的字符串
        }
        #endregion
    }
}