#set the strings

$method="GET";
$appid="d6468df6c1e8419fb5ec50f62be9a28b";
$appkey="15c7a6e1a5bd73500db29dffd0e19b6c6228b044c64348a6f5d6d470c54fc208";
$path="/xxxxx/xxxx/api/v1/users/xxxx/xxxxx";

#build the string to hash

$step1="$method\\n $datestring\\n $appid\\n $path";

#hmac sha256hash the string

$step2=hmac_sha256_hex($step1, $appkey);