- hash_hmac: documentation ( source)
- base64_encode: documentation ( source)
<?php
$customer = "HwM3V6eqEnOWrUdBhLF79N4iOwxI9Vh1Th0FbaAXres&pZPHkkVUQ7l9Ll2KSLUQQcb4gb1ASSUMSFbOVMM10g";
$foo = hash_hmac("sha1", $customer, false);
echo base64_encode($foo);
?>