Question

I am tying to implement a progressive hmac with PHP and JS. I think I got the js figured out using crypto.js

var hmac = CryptoJS.algo.HMAC.create(CryptoJS.algo.SHA256, "Secret Passphrase");

hmac.update("Message Part 1");
hmac.update("Message Part 2");
hmac.update("Message Part 3");

var hash = hmac.finalize();

Taken straight from crypto.js I’m trying to figure out how to duplicate this on the server side with PHP 5.3

Any help on this would be great!

Answer 1

You can use hash_init(), hash_update() and hash_final():

$ctx = hash_init('sha256', HASH_HMAC, 'Secret Passphrase');
hash_update($ctx, 'Message Part 1');
hash_update($ctx, 'Message Part 2');
hash_update($ctx, 'Message Part 3');
$result = hash_final($ctx);

echo $result;