Re: [Classpathx-crypto] Primes and BigInteger

[Raif S. Naffah]

well, i guessed it may be the case and that's why i asked for somebody who
can inspect the sources (of the JDK) to tell me/us more.  thanx for that.

the GNU crypto lib solves this problem by implementing a more reliable and i
think faster primality test based on Colin Plumb's tests (as the info page
states).

by the way, is there a bug number in the bug parade of Sun that points to
this problem?


cheers;
rsn
----- Original Message -----
From: "Marcel Winandy" <address@hidden>
To: <address@hidden>
Sent: Wednesday, April 17, 2002 11:00 PM
Subject: [Classpathx-crypto] Primes and BigInteger


> Hello!
>
> I've just read that you were wondering about some large primes for which
> java.math.BigInteger.isProbablePrime() returns 'false'. Well, BigInteger
> has indeed a bug in its primality test. BigInteger runs Miller-Rabin
> first. If Miller-Rabin returns 'probable prime' for some number, a
> second test will be made, using Lucas this time. And there is a bug in
> that Lucas algorithm of BigInteger. I don't know exactly what is is,
> because a friend of mine examined several primality test algorithms. He
> found that bug in BigInteger and told me. However, it was a very silly
> mistake as far as I remeber - something like +1 instead of -1. But the
> consequences are enormous - as you have seen.
>
> I hope it will help you.
>
> Bye,
>  Marcel
> --
> Marcel Winandy
> EMail: address@hidden
> http://www-student.informatik.uni-bonn.de/~winandy/
>
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