Subject: Re: The Pledge model -- K5 generates 6 mos income in three days
From: Ian Lance Taylor <>
Date: 26 Jun 2002 21:35:29 -0700

"Stephen J. Turnbull" <> writes:

> And _some_ software (RSA comes to
> mind) is sufficiently hard to reimplement from the spec (Diffie-
> Hellman IIRC) that making it proprietary always makes business sense.

RSA is easy to implement if you understand number theory.  I did it
once in about a month, and I spent most of the time writing assembler
routines for fast infinite precision arithmetic. That was fifteen
years ago now; it would be much easier today.

Or maybe you meant to say sufficiently *easy* to reimplement from the
spec.  RSA, the algorithm, was, of course, patented.  So
reimplementations, including the one I did, were not actually legal.
RSA, the company, could only make money because of the patent.
Without it, they would have had nothing but a proposal for PKI, which
I expect everybody would have ignored.  (The patent has since expired,
but RSA did OK by making everybody pay for their PKI infrastructure;
the company is now owned by Verisign.)