- hash_hmac: documentation ( source)
- base64_encode: documentation ( source)
<?php
$input = 'POST
8d03746277e04e07fca4d2ecb533cb6f
Tue, 17 Jun 2014 12:17:31 GMT';
$key = 'WFepNDcs8xwypK1sSc8J0xtWNIt/g917dZ21xtQdUCtCR5HazBLgiUnON0N91hVq9ImcC08XUlmyQ57PyNFHlM90e33PW7lB33anZpBT2RB5EVa2mb0TTcnLRGHzzFSA';
$hmac = hash_hmac('sha512', $input, $key, true); // true voor binary output
echo base64_encode($hmac);