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-   -   Bayes' Theorem Question (https://www.mersenneforum.org/showthread.php?t=11942)

R.D. Silverman 2009-05-26 17:04

[QUOTE=CRGreathouse;174866]I've read it (and the one by Damgård, Landrock & Pomerance). I was addressing only the correctness of flouran's result.[/QUOTE]


Mea Culpa. I responded to the wrong post. I meant for flouran
to read it.

flouran 2009-05-26 18:35

[QUOTE=R.D. Silverman;174849]May I suggest that reading the Pomerance & Kim paper would be a
good idea?[/QUOTE]

You're referring to [U]The Probability that a Random Probable Prime is Composite[/U] by Kim and Pomerance? I've read part of it. In your paper, Dr. Silverman, entitled [U]Fast Generation of Random, Strong RSA Primes[/U], you refer to equation 1.6 of the Kim and Pomerance paper:
"Use of the Miller-Rabin algorithm combined with a Lucas or Frobenius strong probable
prime test [5]. According to a very recent paper of Grantham, if one uses a Frobenius
probable prime test, the probability that a candidate is composite when the tests say
`prime' is less than 1/1770, as opposed to the 1/4 one gets with Miller-Rabin alone. If one
performs a single Miller-Rabin test, followed by T Frobenius tests, the probability of error
for 512-bit primes is then less than 1.5*10^-17(1/1770)^T [Pomerance-Kim, equation 1.6]. To achieve a
probability of 2^-100, T = 4 sufficies. One should be able to apply the analytical techniques
of [3] to the Grantham algorithm to arrive at even stronger probability estimates. That
is to say the number 1.5*10^-17 can probably be reduced, but the method is as yet too
new for anyone to have done this analysis. However, the correctness of the 1.5 * 10^-17
bound is not in question."
May I ask your reasons?

flouran 2009-05-26 19:12

[QUOTE=flouran;174896]You're referring to [U]The Probability that a Random Probable Prime is Composite[/U] by Kim and Pomerance? I've read part of it. In your paper, Dr. Silverman, entitled [U]Fast Generation of Random, Strong RSA Primes[/U], you refer to equation 1.6 of the Kim and Pomerance paper:
"Use of the Miller-Rabin algorithm combined with a Lucas or Frobenius strong probable
prime test [5]. According to a very recent paper of Grantham, if one uses a Frobenius
probable prime test, the probability that a candidate is composite when the tests say
`prime' is less than 1/1770, as opposed to the 1/4 one gets with Miller-Rabin alone. If one
performs a single Miller-Rabin test, followed by T Frobenius tests, the probability of error
for 512-bit primes is then less than 1.5*10^-17(1/1770)^T [Pomerance-Kim, equation 1.6]. To achieve a
probability of 2^-100, T = 4 sufficies. One should be able to apply the analytical techniques
of [3] to the Grantham algorithm to arrive at even stronger probability estimates. That
is to say the number 1.5*10^-17 can probably be reduced, but the method is as yet too
new for anyone to have done this analysis. However, the correctness of the 1.5 * 10^-17
bound is not in question."
May I ask your reasons?[/QUOTE]

Thus, it seems to me that you just multiplied the two probabilities together, rather than using Bayes' Theorem. Am I right or simply deluded?


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