Subject: [openpgp] SHA3 is standardised as FIPS 202

From: ianG <[email-masked]>
Date: Thu, 06 Aug 2015 19:53:00 +0100

It looks like SHA3 is now out as FIPS 202.

http://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf

I think.

Now, SHA3 or Keccak as it was better known, is built using the sponge 
construction idea.  Included in the design are a couple of XOFs or 
extendable output functions called SHAKE128 and SHAKE256.

I think these XOFs can be used as encryption algorithms in XOR-stream mode.

Which brings us to a point worth thinking about.  For a future OpenPGP 
release, we could use SHA3 for both the hash algorithm and the stream 
cipher.  Etc.  (There are supposed to be modes that you can do for 
authenticated encryption as well.)

Which then gives us the opportunity to have ONE algorithm provide a much 
larger space of our needs.  If we the SHA3 engine were to form the basis 
of all the symmetric needs, then this would provide for a minimal 
implementation with less code and less complexity.

E.g., we could simply set the Mandatory to Implement (MTI) algorthm to 
the SHA3 family.

Worthwhile?  I'm not saying this will work - I'm just holding out the 
thought experiment that we could substantially ease the burden on 
developers and implementers if we could simplify the set down to one 
common family.

iang

---

From: Hanno Böck <[email-masked]>
Date: Thu, 6 Aug 2015 18:47:25 -0700

On Thu, 06 Aug 2015 19:53:00 +0100
ianG <[email-masked]> wrote:

> Which brings us to a point worth thinking about.  For a future
> OpenPGP release, we could use SHA3 for both the hash algorithm and
> the stream cipher.  Etc.  (There are supposed to be modes that you
> can do for authenticated encryption as well.)

The keccak (aka sha3) authors submitted two proposals for authenticated
encryption modes to the CAESAR competition:
http://competitions.cr.yp.to/caesar-submissions.html
(ketje and keyak)

(caesar is a competition to find new authenticated encryption algs -
it's currently in round 2, it's still some time until final results are
expected - late 2017.)

-- 
Hanno Böck
http://hboeck.de/

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