Re: Fermat's primality test vs. Miller-Rabin

2005-11-14 Thread Travis H.
Although the Carmichael numbers fool the Fermat test (that is, $a^{n-1} = 1 (n)$) for *all* a, I thought it would work properly if a shares a factor with n. Yes I guess the difference is that with MR you are trying to find a number that is *likely* a prime, whereas with Fermat you are

Re: Fermat's primality test vs. Miller-Rabin

2005-11-14 Thread Alexander Klimov
On Fri, 11 Nov 2005, Joseph Ashwood wrote: From: Charlie Kaufman [EMAIL PROTECTED] I've heard but not confirmed a figure of one failure in 20 million. I've never heard an estimate of the probability that two runs would fail to detect the composite. It couldn't be better than one failure is 20

Re: On Digital Cash-like Payment Systems

2005-11-14 Thread Travis H.
Don't ever encrypt the same message twice that way, or you're likely to fall to a common modulus attack, I believe. Looks like it (common modulus attack involves same n, different (e,d) pairs). However, you're likely to be picking a random symmetric key as the message, and Schneier even

RE: On Digital Cash-like Payment Systems

2005-11-14 Thread Whyte, William
Don't ever encrypt the same message twice that way, or you're likely to fall to a common modulus attack, I believe. Looks like it (common modulus attack involves same n, different (e,d) pairs). However, you're likely to be picking a random symmetric key as the message, and Schneier