Encrypt/Decrypt using Bouncy Castle in C#

I am using the "BouncyCastle.Crypto.dll" for encrypt/decrypt a string in my app. I am using the following code from this blog: I have a class BCEngine, exactly the same as the one given in the link mentioned above. ``` public class BCEngine { private readonly Encoding _encoding; private readonly IBlockCipher _blockCipher; private PaddedBufferedBlockCipher _cipher; private IBlockCipherPadding _padding; public BCEngine(IBlockCipher blockCipher, Encoding encoding) { _blockCipher = blockCipher; _encoding = encoding; } public void SetPadding(IBlockCipherPadding padding) { if (padding != null) _padding = padding; } public string Encrypt(string plain, string key) { byte[] result = BouncyCastleCrypto(true, _encoding.GetBytes(plain), key); return Convert.ToBase64String(result); } public string Decrypt(string cipher, string key) { byte[] result = BouncyCastleCrypto(false, Convert.FromBase64String(cipher), key); return _encoding.GetString(result); } /// <summary> /// /// </summary> /// <param name="forEncrypt"></param> /// <param name="input"></param> /// <param name="key"></param> /// <returns></returns> /// <exception cref="CryptoException"></exception> private byte[] BouncyCastleCrypto(bool forEncrypt, byte[] input, string key) { try { _cipher = _padding == null ? new PaddedBufferedBlockCipher(_blockCipher) : new PaddedBufferedBlockCipher(_blockCipher, _padding); byte[] keyByte = _encoding.GetBytes(key); _cipher.Init(forEncrypt, new KeyParameter(keyByte)); return _cipher.DoFinal(input); } catch (Org.BouncyCastle.Crypto.CryptoException ex) { throw new CryptoException(ex.Message); } } } ``` I am using an asp.net form in which i have written code as given below: ``` public partial class EncryptionForm : System.Web.UI.Page { Encoding _encoding; IBlockCipherPadding _padding; string key = "DFGFRT"; string textToBeEncrypted = "Original text. Please encrypt me."; string txtEncryptedText = string.empty; string txtDecryptedText = string.empty; protected void Page_Load(object sender, EventArgs e) { _encoding = Encoding.ASCII; Pkcs7Padding pkcs = new Pkcs7Padding(); _padding = pkcs; } protected void btnEncrypt_Click(object sender, EventArgs e) { txtEncryptedText = AESEncryption(textToBeEncrypted, key, true); } protected void btnDecrypt_Click(object sender, EventArgs e) { txtDecryptedText = AESDecryption(txtEncryptedText.Text, key, true); } public string AESEncryption(string plain, string key, bool fips) { BCEngine bcEngine = new BCEngine(new AesEngine(), _encoding); bcEngine.SetPadding(_padding); return bcEngine.Encrypt(plain, key); } public string AESDecryption(string cipher, string key, bool fips) { BCEngine bcEngine = new BCEngine(new AesEngine(), _encoding); bcEngine.SetPadding(_padding); return bcEngine.Decrypt(cipher, key); } } ``` Not sure, but due to some reason, I get an exception when I call the btnEncrypt_Click "Key length not 128/192/256 bits." Can anybody please guide? I am a complete newbie to this. Thanks in Advance.