RSA Weak?

Robert J. Hansen rjh at
Fri Nov 2 21:00:45 CET 2007

Alexander W. Janssen wrote:
> How do you come to that figure? A keyspace of 1024 is the double
> amount of 1023 bit, so I'm curious how you come to that figures.

A keyspace of 1024 bits is double that of 1023 bits.  Prime numbers
become more scarce as they go on.  For instance, there are two primes in
a keyspace of two bits.  In a seven-bit keyspace--which, by your logic,
there should be thirty-two times as many primes--there are only twelve
and a half times as many.

Primes are spaced out further and further as numbers grow larger and larger.

In this case, Arjen Lenstra is closing in on RSA-1024 with great
alacrity.  Lenstra is a reputable cryptographer, and his results are
quite interesting.

Read this:

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