----- Original Message -----
From: "Nicolas Rachinsky" <[EMAIL PROTECTED]>
Subject: Re: Fermat's primality test vs. Miller-Rabin
* Joseph Ashwood <[EMAIL PROTECTED]> [2005-11-22 02:50 -0800]:
16384 times
..................
If I remember the proof of MR correctly it assumes an odd number. Were
all your questions odd?
The random numbers tested were almost certainly not all odd, no filtering
was done on random.
If not, please try again with odd numbers only.
I'm running an abbreviated test right now, and it's looking less impressive,
I have to assume I'm hitting a bad streak somehow. Real bad, 30 numbers
tested, no primes at all so far, I see one that has passed 79 tests. I have
to assume I'm missing something really stupid at this point in my new number
chooser that I don't have the time to find right now. So I'm asking for
anyones help in pointing out to me, why after I let it go the full 128 runs
(that is 128 numbers that passed a single round of MR) I didn't get a single
number to pass more than 79? Did I just hit a really, really bad streak?
The exact code for the function and the support variables :
static int lenNum = 512;
static SecureRandom rand = new SecureRandom();
static BigInteger two = BigInteger.valueOf(2);
static BigInteger chooseValue()
{
//pick a random integer
BigInteger curNum = null;
byte [] rawBytes = new byte[lenNum/8];
rand.nextBytes(rawBytes);
curNum = new BigInteger(rawBytes);
//make sure it's odd
if(curNum.mod(BigInteger.valueOf(2)).compareTo(BigInteger.ZERO) == 0)
{
curNum = curNum.add(BigInteger.ONE);
}
//it's 0 or negative try again
if(curNum.compareTo(BigInteger.ZERO)<=0)
{
return chooseValue();
}
return curNum;
}
This should choose a 512-bit random odd positive number, unless I'm missing
something horribly, horribly braindead.
Anyway, back to trying to design a "cool" user interface (anyone who knows
me knows that the cue to begin laughing, I can't design a UI for sh*t).
Joe
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