- substr: documentation ( source)
- var_dump: documentation ( source)
- hash_hmac: documentation ( source)
<?php
$hashn = hash_hmac('sha256', '', '7d87ae991cd4854952ebc9a6bea989ae1ec8974983c22cb9d27ee0e60113b1e1');
$hashn = substr($hashn,0,64);
var_dump($hashn);