On 09/03/2013 03:06 PM, Brian Burkhalter wrote:
So it looks like there are two decisions to be made on this topic:
On Sep 3, 2013, at 1:21 AM, Paul Sandoz wrote:
add the following method to BigInteger
public boolean isProbablePrime(int certainty, Random end) ,
which allows primality testing with arbitrary Random objects.
In many cases, using a well seeded normal Random object will work
just fine, and this will give users the ability to provide their own
Random objects
This sounds like a very good solution to me. That way someone can decide
whether they want to take the hit with SecureRandom, or if Random is good
enough.
Yes.
1) Add BigInteger.isProbablePrime(int certainty, Random rnd) {}
So offhand, I wouldn't commit to saying if SecureRandom is necessary or not,
but it wouldn't surprise me.
My intuition is that the new algorithm for TLR might be sufficient as input to
this Monte-Carlo algorithm, but i don't have any hard empirical data.
2) Replace SR with TLR as the default Random in
BigInteger.passesMillerRabin(int iterations, Random rnd) {}.
Any further comments from those adept at this topic?
I assume you mean to change line 898:
if (rnd == null) {
rnd = ThreadLocalRandom.current();; // was: getSecureRandom();
}
This seems fine in terms of sufficient RNG quality and better
performance. Also in terns of being for sure thread-safe
even though it uses no locks/sync: there are no possible async
or parallel calls from entry into this method, so using
thread-local one is fine.
The new SplittableRandom class might be a better choice but
can't be used here because it doesn't subclass Random. Oh well.
-Doug
