Specified key is not a valid size for this algorithm

Question

I have with this code:

RijndaelManaged rijndaelCipher = new RijndaelManaged();

            // Set key and IV
            rijndaelCipher.Key = Convert.FromBa         


        

Answer 1

here is the class i created

public class ByteCipher
{
    // This constant is used to determine the keysize of the encryption algorithm in bits.
    // We divide this by 8 within the code below to get the equivalent number of bytes.
    private int _Keysize = (int)GlobalConfiguration.DataEncode_Key_Size;

    private byte[] saltStringBytes;

    private byte[] ivStringBytes;
    // This constant determines the number of iterations for the password bytes generation function.
    private const int DerivationIterations = 1000;
    private string _passPhrase = GlobalConfiguration.DataEncode_Key;

    private const string salt128 = "kljsdkkdlo4454GG";
    private const string salt256 = "kljsdkkdlo4454GG00155sajuklmbkdl";

    public ByteCipher(string passPhrase = null, DataCipherKeySize keySize = DataCipherKeySize.Key_128)
    {
        if (!string.IsNullOrEmpty(passPhrase?.Trim()))
            _passPhrase = passPhrase;
        _Keysize = keySize == DataCipherKeySize.Key_256 ? 256 : 128;
        saltStringBytes = _Keysize == 256 ? Encoding.UTF8.GetBytes(salt256) : Encoding.UTF8.GetBytes(salt128);
        ivStringBytes = _Keysize == 256 ? Encoding.UTF8.GetBytes("SSljsdkkdlo4454Maakikjhsd55GaRTP") : Encoding.UTF8.GetBytes("SSljsdkkdlo4454M");
    }

    public byte[] Encrypt(byte[] plainTextBytes)
    {
        if (plainTextBytes.Length <= 0)
            return plainTextBytes;

        using (var password = new Rfc2898DeriveBytes(_passPhrase, saltStringBytes, DerivationIterations))
        {
            var keyBytes = password.GetBytes(_Keysize / 8);
            using (var symmetricKey = new RijndaelManaged())
            {
                symmetricKey.BlockSize = _Keysize;
                symmetricKey.Mode = CipherMode.CBC;
                symmetricKey.Padding = PaddingMode.PKCS7;
                using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes))
                {
                    using (var memoryStream = new MemoryStream())
                    {
                        using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                        {
                            cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                            cryptoStream.FlushFinalBlock();
                            // Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
                            var cipherTextBytes = saltStringBytes;
                            cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
                            cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
                            memoryStream.Close();
                            cryptoStream.Close();
                            return cipherTextBytes;
                        }
                    }
                }
            }
        }
    }

    public byte[] Decrypt(byte[] cipherTextBytesWithSaltAndIv)
    {
        if (cipherTextBytesWithSaltAndIv.Length <= 0)
            return cipherTextBytesWithSaltAndIv;
        var v = Encoding.UTF8.GetString(cipherTextBytesWithSaltAndIv.Take(_Keysize / 8).ToArray());
        if (v != salt256 && v != salt128)
            return cipherTextBytesWithSaltAndIv;

        var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((_Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((_Keysize / 8) * 2)).ToArray();

        using (var password = new Rfc2898DeriveBytes(_passPhrase, saltStringBytes, DerivationIterations))
        {
            var keyBytes = password.GetBytes(_Keysize / 8);
            using (var symmetricKey = new RijndaelManaged())
            {
                symmetricKey.Mode = CipherMode.CBC;
                symmetricKey.Padding = PaddingMode.PKCS7;
                symmetricKey.BlockSize = _Keysize;

                using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
                {
                    using (var memoryStream = new MemoryStream(cipherTextBytes))
                    {
                        using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                        {
                            var plainTextBytes = new byte[cipherTextBytes.Length];
                            var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                            memoryStream.Close();
                            cryptoStream.Close();
                            return plainTextBytes;
                        }
                    }
                }
            }
        }
    }
}