public void AesEncryptionTool_CanEncryptAndDecryptText()
        {
            const string teststring = "Hello world!";
            const string passphrase = "The quick brown fox jumps over the lazy dog.";

            AesEncryptionTool tool = new AesEncryptionTool();

            string ciphertext = tool.EncryptText(teststring, passphrase);
            Assert.AreNotEqual(teststring, ciphertext);

            string decryptedText = tool.DecryptText(ciphertext, passphrase);
            Assert.AreEqual(teststring, decryptedText);
        }