How to Encrypt/Decrypt Password in C#?

//Code Behiend C#
public static void PageLoad()
{
string strKey = "Your Private Key";

//For Encrypt
strKey strName = "administrator";
string strEPassword = Encrypt(strName,strKey);

//For Decrypt
string strEncryptKey = "3zm5dPl2XoXFFcCite50AiKVto/mOlKCR24YFh4XSU0=";
string strDPassword = Decrypt(strEncryptKey,strKey);

}

//Add This Library in Your Page
using System.Security.Cryptography;

public static string GenerateAPassKey(string passphrase)
{
string passPhrase = passphrase;
string saltValue = passphrase;
string hashAlgorithm = "SHA1";
int passwordIterations = 2;
int keySize = 256;
byte[] saltValueBytes = Encoding.ASCII.GetBytes(saltValue);
PasswordDeriveBytes pdb = new PasswordDeriveBytes(passPhrase, saltValueBytes, hashAlgorithm, passwordIterations);
byte[] Key = pdb.GetBytes(keySize / 11);
String KeyString = Convert.ToBase64String(Key);
return KeyString;
}

public static string Encrypt(string plainStr, string KeyString)
{
RijndaelManaged aesEncryption = new RijndaelManaged();
aesEncryption.KeySize = 256;
aesEncryption.BlockSize = 128;
aesEncryption.Mode = CipherMode.ECB;
aesEncryption.Padding = PaddingMode.ISO10126;
byte[] KeyInBytes = Encoding.UTF8.GetBytes(KeyString);
aesEncryption.Key = KeyInBytes;
byte[] plainText = ASCIIEncoding.UTF8.GetBytes(plainStr);
ICryptoTransform crypto = aesEncryption.CreateEncryptor();
byte[] cipherText = crypto.TransformFinalBlock(plainText, 0, plainText.Length);
return Convert.ToBase64String(cipherText);
}

public static string Decrypt(string encryptedText, string KeyString)
{
RijndaelManaged aesEncryption = new RijndaelManaged();
aesEncryption.KeySize = 256;
aesEncryption.BlockSize = 128;
aesEncryption.Mode = CipherMode.ECB;
aesEncryption.Padding = PaddingMode.ISO10126;
byte[] KeyInBytes = Encoding.UTF8.GetBytes(KeyString);
aesEncryption.Key = KeyInBytes;
ICryptoTransform decrypto = aesEncryption.CreateDecryptor();
byte[] encryptedBytes = Convert.FromBase64CharArray(encryptedText.ToCharArray(), 0, encryptedText.Length);
return ASCIIEncoding.UTF8.GetString(decrypto.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length));
}