Is there a way to generate same Hmac hash output from PHP as done with nodejs?

Question

Following is my nodejs function for creating HMAC hash -

function hash() {
    key = "hello";
    msg = "Hello";
    var hmac = crypto.createHmac('sha256', key);
    hmac.update(msg, 'utf8');
    var digest = hmac.digest();
    console.log('---hash =======>' + digest);
    return digest;
}

function hmacHex(key, msg) {
    var hmac = crypto.createHmac('sha256', key);
    hmac.update(msg, 'utf8');
    var digest = hmac.digest('hex');
    console.log('---hmacHex ====>' + digest);
    return digest;
}

var res = hash();
hmacHex("hello", res);

Copy

OUTPUT FROM hash() => }/�(K=�����('�Zt�h�\D�Z��@ywڦ�

OUTPUT FROM hmaxHex() => 692a18bd347476d28300e579794ba799cda80625191ef71783fce95692c2b6f9
Copy

Following is my PHP equivalent code for generating above mentioned output -

class Signature{

public function hash()
    {
        $key = "hello";
        $msg = "Hello";
        $hash = hash_hmac('sha256', utf8_encode($msg), $key, true);
        error_log('---hash ===>'.$hash);
        return $hash;
    }

public function hmacHex($msg)
    {
        $key = "hello";
        $hash = hash_hmac('sha256', utf8_encode($msg), $key, false);
        error_log('---hmacHex ===>' . $hash);
        return $hash;
    }
}

$obj = new Signature();

$res = $obj->hash();
$obj->hmacHex($res);
Copy

OUTPUT FROM hash() => }/?(K=?????('?Zt?h?\D?Z??@ywڦ?

OUTPUT FROM hmacHex => d920859abc579a070f2f8177e71d8431955784c8ed1d596b3364871ba35b5951
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From the outputs, it is clear that in nodejs I am getting replacement characters whereas in PHP it appears as a question mark.

I am trying to generate exactly the same output from my PHP code so that when the outputs are rehashed it should be the same.

Answer 1

your $key php side must be utf8_encode because on the node side crypto.createHmac('sha256', key);

the key here is utf8 encoded by crypto.createHmac.