getRandomBytes(): use HMAC-SHA256.
getRandomBytes(): use HMAC-SHA256.

Now that we have an interface to use this API directly, via ACL GENPASS,
we are no longer sure what people could do with it. So why don't make it
a strong primitive exported by Redis in order to create unique IDs and
so forth?

The implementation was tested against the test vectors that can
be found in RFC4231.

pmem/redis,pmem/redis,pmem/redis,pmem/redis