On Fri, 04 Jul 2008 20:46:13 -0700
Allen [EMAIL PROTECTED] wrote:
Is there an upper limit on the number of RSA Public/Private 1024 bit
key pairs possible? If so what is the relationship of the number of
1024 bit to the number of 2048 and 4096 bit key pairs?
There are limits, but they're not particularly important.
I'll oversimplify. Roughly speaking, a 1024-bit RSA public key is the
product of two 512-bit primes. According to the Prime Number Theorem,
the number of primes n is approximately n/log(n). Actually, what we
need is the number of primes 2^511 and 2^512, but that correction
doesn't make much differences -- work through the math yourself to see
that. Call the number of such primes P.
Now, we need two such primes. There are therefore P^2 pairs, more than
2^1000. The numbers are very much larger for 2048- and 4096-bit keys,
but I'll leave those as an exercise for the reader.
--Steve Bellovin, http://www.cs.columbia.edu/~smb
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