Pseudorandom function in Hive?

I'm trying to get a deterministic, pseudorandom function in Hive. I tried checksum, but apparently that's just SQL, not Hive. I did

select hash(1) gave me 1

select rand(1), rand(2), rand(3) got me 0.730878191 0.731146936 0.731057369

Is there a cryptographically secure hash in Hive? Why is rand not random?