Public key crypto by hand

David SMITH dave.smith at
Thu Jul 30 15:57:06 CEST 2009

On Thu, Jul 30, 2009 at 09:30:47AM -0400, Brian Mearns wrote:
> Thanks, Harry. Interesting page, but I don't think primes on the
> order of 3 and 11 really qualify as secure, which was pretty much
> what I figured would be the case: anything that can reasonably be
> done by hand wouldn't be secure.

Your answer implies that you are looking for something that you would
actually use, rather than just a pen-and-paper demo for instruction

In this case, whilst it's not exactly "public key cryptography", even
the simplest algorithms are cryptographically secure with a one-time pad.

Of course, you then have the key exchange problem.

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