Date: Wed, 1 Apr 2020 10:07:07 +0200 (CEST)
From: Leo Perrin <leo.perrin@inria.fr>
To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
Cc: Robert Moskowitz <rgm-sec@htt-consult.com>, 
 "Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu>, 
 Dan Brown <danibrown@blackberry.com>, cfrg@ietf.org
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Thread-Topic: Encrypt in place guidance
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Archived-At: <https://mailarchive.ietf.org/arch/msg/cfrg/2Bk2wMqx-r4ZVkiI6eKJEqp0B-o>
Subject: Re: [Cfrg] Encrypt in place guidance
Precedence: list

Hi,

>> Speck
>=20
> Hmm. Were the design criteria for that algorithm
> ever published in the end? (I've not followed it,
> so they may have been.)

The authors of SPECK put something on eprint [1] but it merely lists public=
 results and claims they already knew about the corresponding attacks. I pe=
rsonally don't find this document convincing at all since it came *after* a=
 public analysis. In my opinion (and it is not a controversial one in the a=
cademic symmetric crypto community), if the designers of a cipher did not p=
ublish their security analysis along with its specification then you should=
 not even consider using the corresponding cipher. Of course, there is also=
 the elephant in the room: SPECK was designed by the same entity as the bac=
kdoored DUAL_EC.

By the way, there are many (many!) 64-bit block ciphers in the literature--=
-see Table 6 of [2]. Full disclosure: I am a co-author of this survey. If y=
ou have questions about it, feel free to ask!

[1] https://eprint.iacr.org/2017/560
[2] https://eprint.iacr.org/2017/511

Cheers,

/L=E9o