- hash_hmac: documentation ( source)
<?php
$apikey='6b00538440c940329fe5ee6f96c6b263';
$apisecret='912a4bbd4714996afb8921f75b43c9d';
$nonce=1434405875;
$uri='https://bittrex.com/api/v1.1/account/getbalances?apikey='.$apikey.'&nonce='.$nonce;
echo $uri;
$sign=hash_hmac('sha512',$uri,$apisecret);
echo $sign;
?>