Yeah, i realized my error when I was outside, but you beat me back to the pc. It should have been

//echo -a $version $file($mircexe).sig $beta $hmac($mircexe,$null,sha1,2)

result: 7.63 ok 0536e81a5595b711016b1b9d37d8b42ff8d693da

$hmac is confusing because everywhere else in the world the syntax is presented as HMAC(key,message) but here it's $hmac(message,key)