phc-discussions - Re: [PHC] Doubts about AntCrypt floating-point use

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Date: Tue, 01 Apr 2014 22:55:01 +0000
From: "Poul-Henning Kamp" <phk@....freebsd.dk>
To: discussions@...sword-hashing.net, Bill Cox <waywardgeek@...il.com>
Subject: Re: [PHC] Doubts about AntCrypt floating-point use

In message <CAOLP8p5X2jDuaCaX_rfzL3Ls61X9iGXFb_6BSYbKX8c+WhRyLQ@...l.gmail.com>
, Bill Cox writes:

I must admit that I had not previously considered floating point
in this context.

There are certainly some (minor) disadvantages with respect to
ensuring correct rounding behaviour and minimizing entropy loss,
but thanks to IEEE those should be manageable problems.

Calling library trig functions is bit too optimistic though.

But pulling in FP also means that you can pull all the
"non-giraffe mathematics"[1] into the cryptographic playpen.

Think about the potential Mandelbrots fractals or The Lorentz
Attractor has as "dial-a-hardness one-way functions[2][3].

It probably is about high time that we eject the "integers-only"
dogma in the non-symmetric parts of cryptography.

Thanks to AntCrypt for inspiring that thought.

Poul-Henning

[1] "Modulus arithmetic is to math, what the giraffe is to zoology."

[2] Not to mention the vast improvement of aesthetic quality in
    crypto-paper illustrations.

[3] At the absolutely ridiculous upper end of FP-password hash
    functions, you take each byte of your password as a signed 8
    bit integer and plug it into the GISS climate model at initial
    temperature at particular grid-points in 1900, and see if you
    get the right level of water in a harbour of your own choice
    in 2100.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@...eBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.