Re: Truelly Random Numbers

[tcmay@got.net (Timothy C. May)]

At 3:11 PM 3/3/96, Gary Howland wrote:

>Timothy C May wrote:
>
>> In some PK code I did several years ago in Mathematica, the primes for the
>> RSA modulus were found by picking a "random" (more on this later) starting
>> point and then counting up from there, testing for primality (actually,
>> pseudoprimality, technically). As one would expect, primes are found fairly
>> quickly.
>
>Surely the process of counting up until you get a prime means
>that the chances of getting certain primes are greater than
>others (eg. 17 is more likely than 19) ?

???

I think you are misunderstanding the point. The count doesn't start at 0,
if this is your point...that would be a lot worse than some primes more
common than other, that would mean everyone uses the same prime, e.g., "2."

Rather, one picks a suitably random number, such as
"836480166228153153328299.....845082582622308645" (lots of digits) and
tests it for primality (pseudoprimality). For a several hundred digit
number, only about a one percent chance or less that it's prime. So, one
iterates upward or downward by two (one first makes sure it's odd, as it
must be to be a possible prime).

Sure, the first prime reached is "more likely" to be selected than the
second or third or nth prime reached, but so what? No outsider knows the
seed value, which is where all of the security resides.

--Tim May

Boycott "Big Brother Inside" software!
We got computers, we're tapping phone lines, we know that that ain't allowed.
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