function sha1KeyedMAC($key, $message) { $c = new SHA1Context(); $s = new SHA1(); $s->reset($c); $s->input($c, $key . $message); $s->result($c); return pack('N5', $c->messageDigest[0], $c->messageDigest[1], $c->messageDigest[2], $c->messageDigest[3], $c->messageDigest[4]); }