加密

    public class PassWord
    {
        //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 static 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);
            }
            return ret.ToString();
        }
        //解密方法  
        public static 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());
        }
        /// <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>
        public static 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>
        public static 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>
        public static 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>
        public static 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>
        public static 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);
        }
    }