Various HMACs generated by nodejs and php

Question

Various HMACs generated by nodejs and php

// base64-encode the binary result of the HMAC computation
$merchantSig = base64_encode(hash_hmac('sha256',$signData,pack("H*" , $hmacKey),true));

Above is the php code that generates the digest.

let h = crypto.createHmac('sha256', hmacKey).update(keyString).digest('base64');

The above nodejs code that generates the digest. The key I am using is hex in both php and node. What should I do differently in node to get the same result as in php. I know php uses a different encoding than nodejs. But what else am I missing here?

+3

node.js php cryptography

Karthik priyadarshan 28 Mar 17 at 7:29

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2 answers

hassan · Answer 1 · 2017-03-28T08:17:52+0000

well there is no difference between hmac in both php and node.js.

this is normal behavior for the two pieces of code you provided.

in your php you are packing

yours$hmacKey

a step that doesn't exist in your node side;

in all the following examples i will use as hmac key and data string 123456

yello

eg:

php without packaging:

$merchantSig = base64_encode(hash_hmac('sha256',$signData, $hmacKey,true));
echo $merchantSig; // output : gKjrFq1nrRP33vGiAK9V1Z5bLX5EFZhcfy2flRIGPEI=

node.js without packaging:

let h = crypto.createHmac('sha256', hmacKey).update(keyString).digest('base64');
console.log(h); // output : gKjrFq1nrRP33vGiAK9V1Z5bLX5EFZhcfy2flRIGPEI=

now package both:

php with packing:

$merchantSig = base64_encode(hash_hmac('sha256',$signData,pack("H*" , $hmacKey),true));
echo $merchantSig; // output : Y8D5crzxQfFkwQn1OJHeZTS1KVuTH0y7qLuxyetE0TY=

node.js with packaginghere is the trick

var h = crypto.createHmac('sha256', hmacKey.packHex()).update(keyString).digest('base64');
//                                          ^^^^^^^^^
console.log(h); // output : Y8D5crzxQfFkwQn1OJHeZTS1KVuTH0y7qLuxyetE0TY=