Kullan hash_hmac :

$sig = hash_hmac('sha256', $string, $secret)

hash_hmac() function burada yardımcı olabilir:

Generate a keyed hash value using the HMAC method

For example, the following portion of code :

$hash = hash_hmac('sha256', 'hello, world!', 'mykey');
var_dump($hash);

Aşağıdaki çıktıyı verir:

string '07a932dd17adc59b49561f33980ec5254688a41f133b8a26e76c611073ade89b' (length=64)

And, to get the list of hashing algorithms that can be used, see hash_algos().