Implementing OTP Google Authenticator on Laravel 4 - laravel

Question

I'm working on integrating 2-factor authentication using https://github.com/ChristianRiesen/otp on a Laravel 4.1.23 site: the secret gets generated fine, the QR code image too, and Google Authenticator is able to scan the image.
However, the code generated on my iPhone inside the Google Authenticator application does not validate. I've followed the example from the README.md.
In my Controller, I have code like the following:
$secret = GoogleAuthenticator::generateRandom();
$url = GoogleAuthenticator::getQrCodeUrl('totp', 'MySite:'.Auth::user()->email, $secret);
// Save the secret with the user's data
if (!Auth::user()->secret) {
Auth::user()->secret = $secret;
Auth::user()->save();
}
return View::make('2fa')->with('secret', $secret)->with('url', $url);
Then in my view (2fa.blade.php), I have code like the following:
<strong>Secret Key:</strong> {{ $secret }}
<strong>QR Code</strong> <br/>
<img src="{{ $url }}" />
<form action="/confirm_key" method="post">
<label for="key">Enter the generated key:</label>
<input type="text" name="key" id="key"/>
<input type="submit" id="submit" value="Confirm Key"/>
</form>
That all appears to be working. The form posts to the following controller function:
public function postTwoFactorAuthentication() {
// Now how to check
$otp = new Otp();
if ($otp->checkTotp(Base32::decode(Auth::user()->secret), Input::get('key'))) {
return 'Verified!';
}
// Wrong key
else {
return 'Invalid key!'
}
}
This is following usage example from the repo pretty closely, but the key (token) never validates. Am I missing something here? Is Laravel screwing with something?
Any help is appreciated.