[denobis]

I think you've substituted

$key = pack("C*", 48, 99, 101, 102, 56, 56, 56, 101, 56, 48, 99, 51, 49, 48, 57, 49, 54, 102, 55, 101, 97, 98, 100, 97, 54, 100, 51, 97, 51, 98, 57, 52);

to

$key="a446fc7f58805dbc1472105773367dac";