C#加密解密大全

1、方法一 (不可逆加密)

    public string EncryptPassword(string PasswordString,string PasswordFormat ) 
    { 
       string  encryptPassword = null;
       if (PasswordFormat="SHA1")
       { 
          encryptPassword=FormsAuthortication.HashPasswordForStoringInConfigFile(PasswordString ,"SHA1"); 
       } 
       elseif (PasswordFormat="MD5") 
       { 
          encryptPassword=FormsAuthortication.HashPasswordForStoringInConfigFile(PasswordString ,"MD5"); 
       }
         return encryptPassword ;
    }

2、方法二 (可逆加密)

 public interface IBindesh
    {
    string encode(string str);
    string decode(string str);
     }

    public class EncryptionDecryption : IBindesh
    {
        public string encode(string str)
         {
            string htext = ""; 

            for ( int i = 0; i < str.Length; i++)
            {
                htext = htext + (char) (str[i] + 10 - 1 * 2);
            }
            return htext;
     }

        public string decode(string str)
        {
            string dtext = ""; 

            for ( int i=0; i < str.Length; i++)
            {
                dtext = dtext + (char) (str[i] - 10 + 1*2);
            }
            return dtext;
        }

3、方法三 (可逆加密)

 const string KEY_64 = "VavicApp";//注意了，是8个字符，，64位

        const string IV_64 = "VavicApp"; 
        public string Encode(string data)
        {
            byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);
            byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);

            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            int i = cryptoProvider.KeySize;
            MemoryStream ms = new MemoryStream();
            CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIV), CryptoStreamMode.Write);

            StreamWriter sw = new StreamWriter(cst);
            sw.Write(data);
            sw.Flush();
            cst.FlushFinalBlock();
            sw.Flush();
            return Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length);

        }

        public string Decode(string data)
         {
            byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);
            byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);

            byte[] byEnc;
            try
            {
                byEnc = Convert.FromBase64String(data);
            }
            catch
            {
                return null;
            }

            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            MemoryStream ms = new MemoryStream(byEnc);
            CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateDecryptor(byKey, byIV), CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(cst);
            return sr.ReadToEnd();
        }

4、MD5不可逆加密    (32位加密)