Different HMACs generated by nodejs and php

问题

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

The above is the php code that generates the digest.

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

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

回答1:

well, there are no difference between the hmac's in both php and node.js .

this is the normal behavior for the two pieces of codes your provided.

in your php you are packing your $hmacKey

the step which is not exists in your node side;

---

in all the next examples i will use 123456 as hmac key and yello as a data string

for example :

php without packing :

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

node.js without packing :

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

---

now let's pack the both :

php with packing :

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

node.js with packing here is the trick

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

---

Update

Here is some online tests for both php & nodejs in the two cases (using pack-without using pack)

php : https://3v4l.org/HCt4g

nodejs : http://rextester.com/YNNWN69327

here is another tests with another keys and strings . for php :

https://3v4l.org/JKdNk

and node.js

http://rextester.com/RXGM49887 ,

来源：https://stackoverflow.com/questions/43063221/different-hmacs-generated-by-nodejs-and-php