The Pure Crypto Project's Hash Function

[Ralf Senderek]

    On Sat, 3 May 2003, Rich Salz wrote:

> But you "invented" a new hashing mechanism.  Why do you think the industry
> has settled on RSA/SHA1 as a standard?

Because it is "cheap" and not because the users understand what they are
doing. There may be other reasons, but none of them is "clarity" or
"conciousness of what's going on".

> I also forgot to ask if we haven't learned enough from PGP: interop is
> important.  What's your compelling reason to throw that away?

First of all, I'm not advocating not to use PGP. I've spend plenty of
time to explain the background principles of PGP, but we have this
complexity problem now and the development of PGP in recent years
does not at all point into a direction to solve this problem.

The short version of my compelling reason is :


Why the Pure Crypto Project started
-----------------------------------

As crypto products have developed over the years they have become more
and more complex and also more inscrutable leaving the user in a fatal
dependence on crypto code which almost nobody fully understands
nor analyses for all its security implications. Most people have
inevitably accepted this situation without being able to know
in detail what they are doing when they use crypto programs,
although the basic principles are widely known, the specifications
are all published and of course the code is open for inspection.
But as the code grows more and more complex it is simply beyond
the state of the art to analyse this sort of code with respect
to all implications for security.

The Pure Crypto Project (PCP) started to turn the process in a
different direction and to tackle the inscrutability problem by
developing a program that consists of a very small amount of
highly readable code that will be clear and understandable not only
for security experts but for many crypto-literate people.
So the most important objective of PCP is to restrict itself to
one well known basic function (RSA and Modular Exponentiaton)
to provide encryption and signing with only a few hundred lines of
security relevant code that can be fully analysed with respect
to its security implications.


> I think this is a real bad approach.
>         /r$

>From the point of view how things have been done in the past
one can only agree, but from the point of view, that it it
neccessary to regain control over what you do when you use
crypto PCP is a very, very good approach!

So please elaborate on your concept of "good" and "bad".


Ralf.



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