using System;
using System.Security.Cryptography;
using System.Text;



public class EncrypHelper
{
    /// <summary>
    ///静态无参构造
    /// </summary>
    static EncrypHelper()
    {
        //默认的密钥
        SecretKey = "";
    }

    /// <summary>
    /// 使用SHA256加密字符串
    /// </summary>
    /// <param name="Source"></param>
    /// <returns></returns>
    public static string EncrypToSHA(string Source)
    {
        SHA256Managed sha256 = new SHA256Managed();
        byte[] s = UTF8Encoding.UTF8.GetBytes(Source);
        byte[] t = sha256.ComputeHash(s);
        return Convert.ToBase64String(t);
    }

    /// <summary>
    /// 缺省的密钥
    /// </summary>
    public static readonly string SecretKey;

    /// <summary>
    /// 使用缺省密钥字符串加密string
    /// </summary>
    /// <param name="original">明文</param>
    /// <returns>密文</returns>
    public static string Encrypt(string original)
    {
        return Encrypt(original, SecretKey);
    }

    /// <summary>
    /// 使用缺省密钥字符串解密string
    /// </summary>
    /// <param name="original">密文</param>
    /// <returns>明文</returns>
    public static string Decrypt(string original)
    {
        try
        {
            return Decrypt(original, SecretKey, System.Text.Encoding.Default);
        }
        catch (Exception)
        {

        }
        return string.Empty;
    }

    /// <summary>
    /// 使用给定密钥字符串加密string
    /// </summary>
    /// <param name="original">原始文字</param>
    /// <param name="key">密钥</param>
    /// <returns>密文</returns>
    public static string Encrypt(string original, string key)
    {
        byte[] buff = System.Text.Encoding.Default.GetBytes(original);
        byte[] kb = System.Text.Encoding.Default.GetBytes(key);
        return Convert.ToBase64String(Encrypt(buff, kb));
    }

    /// <summary>
    /// 使用给定密钥字符串解密string
    /// </summary>
    /// <param name="original">密文</param>
    /// <param name="key">密钥</param>
    /// <returns>明文</returns>
    public static string Decrypt(string original, string key)
    {
        return Decrypt(original, key, System.Text.Encoding.Default);
    }

    /// <summary>
    /// 使用给定密钥字符串解密string,返回指定编码方式明文
    /// </summary>
    /// <param name="encrypted">密文</param>
    /// <param name="key">密钥</param>
    /// <param name="encoding">字符编码方案</param>
    /// <returns>明文</returns>
    public static string Decrypt(string encrypted, string key, Encoding encoding)
    {
        byte[] buff = Convert.FromBase64String(encrypted);
        byte[] kb = System.Text.Encoding.Default.GetBytes(key);
        return encoding.GetString(Decrypt(buff, kb));
    }

    /// <summary>
    /// 生成MD5摘要
    /// </summary>
    /// <param name="original">数据源</param>
    /// <returns>摘要</returns>
    public static byte[] MakeMd5(byte[] original)
    {

        MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
        byte[] keyhash = hashmd5.ComputeHash(original);
        hashmd5 = null;
        return keyhash;
    }

    /// <summary>
    /// 使用给定密钥加密
    /// </summary>
    /// <param name="original">明文</param>
    /// <param name="key">密钥</param>
    /// <returns>密文</returns>
    public static byte[] Encrypt(byte[] original, byte[] key)
    {
        TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
        des.Key = MakeMd5(key);
        des.Mode = CipherMode.ECB;
        return des.CreateEncryptor().TransformFinalBlock(original, 0, original.Length);
    }

    /// <summary>
    /// 使用给定密钥解密数据
    /// </summary>
    /// <param name="encrypted">密文</param>
    /// <param name="key">密钥</param>
    /// <returns>明文</returns>
    public static byte[] Decrypt(byte[] encrypted, byte[] key)
    {
        TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
        des.Key = MakeMd5(key);
        des.Mode = CipherMode.ECB;
        return des.CreateDecryptor().TransformFinalBlock(encrypted, 0, encrypted.Length);
    }
}