On 05/24/2016 10:49 AM, Kia wrote:
I am working on an NTP client/server implementation in ocaml for mirageos
(https://matildah.github.io/posts/2016-05-23-ntp-status.html) and I need to
have access to random numbers -- is
https://github.com/mirage/mirage/blob/master/types/V1.mli#L63 the right way for
for a mirageos library to get random numbers or is this out of date/deprecated?
Is there a reference/example for how a library can use the random number
generation module in mirage?
Hi Kia,
The Random module uses the OCaml runtime's random module. Here's the
header on that module:
" Pseudo-random number generator
This is a lagged-Fibonacci F(55, 24, +) with a modified addition
function to enhance the mixing of bits.
If we use normal addition, the low-order bit fails tests 1 and 7
of the Diehard test suite, and bits 1 and 2 also fail test 7.
If we use multiplication as suggested by Marsaglia, it doesn't fare
much better.
By mixing the bits of one of the numbers before addition (XOR the
5 high-order bits into the low-order bits), we get a generator that
passes all the Diehard tests.
"
Seeding: "Initialize the generator with a random seed chosen in a
system-dependent way. If |/dev/urandom| is available on the host
machine, it is used to provide a highly random initial seed. Otherwise,
a less random seed is computed from system parameters (current time,
process IDs)."
If this is sufficient for your needs, Random is indeed the way to go.
If you need better guarantees, it might be a good idea to talk with the
folks who built ocaml-nocrypto.
Thanks,
Mindy
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