Having read all the criticism of the API, I still don't agree with the 
minimalist view nor do I favor implementing a mathfunc to mirror a 
semi-obscure API, and prefer to keep SRANDOM in a module that fails to 
load if no kernel random source is available  so I'm proposing a new API.

builtin:

zrandint -c /count/=*1 *-U /upper/=*MAX_UINT32 *-L /lower/=*0 *-s 
/scalar /-a /array /-f raw|hex|*dec*

**default output is equivalent to _echo $SRANDOM_. I can special case 
the nonsensical arguments like /count/=0 and /upper/=/lower /if that's 
the wish of the group/. upper/ is inclusive

zrandbyte -c /count/=*8 *-s /scalar /-a /array /-f raw|hex|*hex:*|dec:

     default output format will be a colon-separated string of bytes 
encoded in hex, in an array hex and hex: are equivalent.  I could, 
instead, add another option to specify a separator and default to :.

Parameter:

SRANDOM

     A random, uniformly-distributed, unsigned, 32-bit integer.

mathfunc:

zrandomf()

     produces a random float-point number from 0 to 1  inclusive

zrandomi(/upper/=*MAX_UINT32*,/lower/=*0*,/inclusive/=*0*)

     takes 0 to 3 arguments.  exclusive by default to accommodate 
${string[zrandomi($#string)+1]}

I'm not particularly tied to any of the names except SRANDOM