Working AES

        [Test]
        public void EncryptDataAndDecryptData_TestDataIsCorrect()
        {
            AesCryptator aesCryptator = new AesCryptator();
            string stringToEncrypt = "Hello World";
            //Encrypt the string
            string encryptedString = aesCryptator.EncryptData(stringToEncrypt);
            //Decrypt the string
            string decryptedString = aesCryptator.DecryptData(encryptedString);

            Assert.AreEqual(decryptedString, stringToEncrypt);
        }

public static class CryptationUtility
    {
        public static string BytesToString(byte[] bytesToConvert)
        {
            return Encoding.ASCII.GetString(bytesToConvert);
        }

        public static byte[] StringToBytes(string stringToConvert)
        {
            return Encoding.ASCII.GetBytes(stringToConvert);
        }

        public static string ToUrlSafeBase64(byte[] input)
        {
            return Convert.ToBase64String(input).Replace("+", "-").Replace("/", "_");
        }

        public static byte[] FromUrlSafeBase64(string input)
        {
            return Convert.FromBase64String(input.Replace("-", "+").Replace("_", "/"));
        }
    }

public class AesCryptator
    {
        private RijndaelManaged _rijndaelObj;

        public AesCryptator()
        {
            _rijndaelObj = new RijndaelManaged();
        }

        public void SetRijndaelObject(RijndaelManaged rijndaelObj)
        {
            _rijndaelObj = rijndaelObj;
        }

        public RijndaelManaged GetRijndaelObject()
        {
            return _rijndaelObj;
        }

        public AesData GetAesData()
        {
            string key = Encoding.ASCII.GetString(_rijndaelObj.Key);
            string iv = Encoding.ASCII.GetString(_rijndaelObj.IV);
            return new AesData(key, iv);
        }

        public string EncryptData(string str)
        {
            //Create a memory stream to hold the encrypted data
            MemoryStream msEncrypt = new MemoryStream();

            try
            {
                //Create a new instance of the CryptoStream class
                CryptoStream csEncrypt = new CryptoStream(msEncrypt, _rijndaelObj.CreateEncryptor(), CryptoStreamMode.Write);

                //Create stream writer
                StreamWriter swEncrypt = new StreamWriter(csEncrypt);

                //Encrypt the string
                swEncrypt.Write(str);

                //Clean up. csEncrypt has to be closed before getting data from memorystream
                swEncrypt.Close();
                csEncrypt.Close();

                //Convert encrypted data to string
                //string encryptedString = Convert.ToBase64String(ms.ToArray());
                string encryptedString = CryptationUtility.ToUrlSafeBase64(msEncrypt.ToArray());

                //Clean up
                msEncrypt.Close();

                //Return encrypted string
                return encryptedString;
            }
            catch (Exception ex)
            {
                throw new AesCryptationException("Error in encrypting - " + ex.Message);
            }
        }

        public string DecryptData(string encryptedString)
        {
            try
            {
                //Convert the encrypted string to a byte array
                //byte[] encryptedBytes = System.Convert.FromBase64String(encryptedString);
                byte[] encryptedBytes = CryptationUtility.FromUrlSafeBase64(encryptedString);

                //Convert the byte array into a memory stream for decryption
                MemoryStream msDecrypt = new MemoryStream(encryptedBytes);

                ////Create a new instance of the CryptoStream class
                CryptoStream csDecrypt = new CryptoStream(msDecrypt, _rijndaelObj.CreateDecryptor(), CryptoStreamMode.Read);

                //Decrypt the stream
                StreamReader srDecrypt = new StreamReader(csDecrypt);

                //Convert the decrypted stream into a string
                string decryptedString = srDecrypt.ReadToEnd();

                //Clean up
                srDecrypt.Close();
                csDecrypt.Close();
                msDecrypt.Close();

                //return decrypted string
                return decryptedString;
            }
            catch (Exception ex)
            {
                throw new AesCryptationException("Error in decrypting - " + ex.Message);
            }
        }
    }