Help generate Facebook API "Sig" in Python

Question

Hi guys,

I have been struggling with this for over two days and I could use your help. Here's the problem:

Whenever a request is made to the Facebook REST server, we have to send an additional parameter called "sig". This sig is generated using the following algorithm:

<?php

$secret = 'Secret Key'; // where 'Secret Key' is your application secret key 
$args = array(
'argument1' => $argument1,
'argument2' => $argument2); // insert the actual arguments for your request in place of these example args 
$request_str = '';
foreach ($args as $key => $value) {
$request_str .= $key . '=' . $value; // Note that there is no separator.
}
$sig = $request_str . $secret;
$sig = md5($sig);

?>

More information about this: http://wiki.developers.facebook.com/index.php/How_Facebook_Authenticates_Your_Application

I have been trying to reproduce this piece of code in Python, here is my attempt:

def get_signature(facebook_parameter):
    sig = ""
    for key, value in facebook_parameter.parameters:
        sig += key + "=" + value
    sig += facebook_parameter.application_secret
    return hashlib.md5(sig).hexdigest()

facebook_paremeter.parameters is a list that looks like this:

[('api_key', '...'), ('v', '1.0'), ('format', 'JSON'), ('method', '...')]

and facebook_paremeter.application_secret is a valid app secret.

This code is running on the Google App Engine development platform (if that makes any difference). Python 2.6.4.

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Can somebody help me find out where my code is going wrong?

Thanks, Sri

Answer 1

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