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August 11, 2011 15:49
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Decode Facebook signed_request with NodeJS
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//npm install b64url | |
//A signed_request for testing: | |
//WGvK-mUKB_Utg0l8gSPvf6smzacp46977pTtcRx0puE.eyJhbGdvcml0aG0iOiJITUFDLVNIQTI1NiIsImV4cGlyZXMiOjEyOTI4MjEyMDAsImlzc3VlZF9hdCI6MTI5MjgxNDgyMCwib2F1dGhfdG9rZW4iOiIxNTI1NDk2ODQ3NzczMDJ8Mi5ZV2NxV2k2T0k0U0h4Y2JwTWJRaDdBX18uMzYwMC4xMjkyODIxMjAwLTcyMTU5OTQ3NnxQaDRmb2t6S1IyamozQWlxVldqNXp2cTBmeFEiLCJ1c2VyIjp7ImxvY2FsZSI6ImVuX0dCIiwiY291bnRyeSI6ImF1In0sInVzZXJfaWQiOiI3MjE1OTk0NzYifQ | |
function parse_signed_request(signed_request, secret) { | |
encoded_data = signed_request.split('.',2); | |
// decode the data | |
sig = encoded_data[0]; | |
json = base64url.decode(encoded_data[1]); | |
data = JSON.parse(json); // ERROR Occurs Here! | |
// check algorithm - not relevant to error | |
if (!data.algorithm || data.algorithm.toUpperCase() != 'HMAC-SHA256') { | |
console.error('Unknown algorithm. Expected HMAC-SHA256'); | |
return null; | |
} | |
// check sig - not relevant to error | |
expected_sig = crypto.createHmac('sha256',secret).update(encoded_data[1]).digest('base64').replace(/\+/g,'-').replace(/\//g,'_').replace('=',''); | |
if (sig !== expected_sig) { | |
console.error('Bad signed JSON Signature!'); | |
return null; | |
} | |
return data; | |
} |
Danke!
Here is another impl of parsing Facebook signed request for Node.js - https://gist.github.com/dibikhin/16c6df88cee2fefa3441c0c6d6e34fd3
It's well-structured, self-tested and has zero dependencies. It has been successfully tested on production a few times by these steps. Test it carefully anyway.
(The original Facebook code on PHP for Data Deletion Callback.)
I've found this gist after I'd implemented my own :)
@dibikhin Thanks.
https://gist.github.com/jottenlips/6ed1b49e534e8277f7373d53fe0b7547 This is what I am going with, got as close to the PHP as I could.
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Thank you :))