How can I pass up an exception
<p>How can I handle an expected exception?</p>

<p>I have code in my MVC controller that calls the following:</p>

<pre><code>u.RowKey == new SimplerAES().Dec(HttpServerUtility.UrlTokenDecode(id)));
</code></pre>

<p>In my other SimplerAES class:</p>

<pre><code>    public string Dec(byte[] encrypted)
    {
        return encoder.GetString(Decrypt(encrypted));
    }

    public byte[] Decrypt(byte[] buffer)
    {
        try {
            MemoryStream decryptStream = new MemoryStream();
            using (CryptoStream cs = new CryptoStream(decryptStream, decryptor, CryptoStreamMode.Write))
            {
                cs.Write(buffer, 0, buffer.Length);
            }
            return decryptStream.ToArray();
        } catch(CryptographicException e){
            //... do something with it ...
            return null; // I put the return null here as I got a syntax message saying
                         // not all code returns
        }
    }
</code></pre>

<p>Can someone please explain how I get the message that decrypt failed all the way up 
to the point where I first try to get the RowKey. Do I have to put u.RowKey within
a try catch as well?</p>
