[19079] in cryptography@c2.net mail archive
Re: Fermat's primality test vs. Miller-Rabin
daemon@ATHENA.MIT.EDU (Sidney Markowitz)
Sat Dec 3 13:55:31 2005
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Sun, 04 Dec 2005 03:41:54 +1300
From: Sidney Markowitz <sidney@sidney.com>
To: Joseph Ashwood <ashwood@msn.com>
Cc: cryptography@metzdowd.com
In-Reply-To: <BAY0-SMTP0499FBEE8C0BA37A1E6F73AC4D0@phx.gbl>
Joseph Ashwood wrote:
> byte [] rawBytes = new byte[lenNum/8];
> rand.nextBytes(rawBytes);
> curNum = new BigInteger(rawBytes);
I haven't thought through why it would produce non-primes, but it
doesn't seem to do what you want. That produces a 512 bit
twos-complement number, which gives you a 511 bit positive integer, not
512 bit. It also is unnecessarily complicated compared to this form of
the BigInteger constructor and the or method (see the javadoc):
curNum = BigInteger.ONE.or(new BigInteger(512, rand));
-- Sidney Markowitz
http://www.sidney.com
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