Do you concider Tetra encryption algorithms secure?

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Markus Jansson

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Jan 1, 2005, 6:14:12 PM1/1/05
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Simple, quick question.

I dont, simply because they havent published them for peer-review and
they have made poor crypto before. But I just want to hear a quick
opinion from the newsgroups most regular and respected contributors. :)

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Douglas A. Gwyn

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Jan 2, 2005, 1:21:57 AM1/2/05
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Markus Jansson wrote:
> I dont, simply because they havent published them for peer-review and
> they have made poor crypto before.

With no information to go on, there is no reason to
consider them secure, nor to be certain that they are
insecure. Going purely by historical statistics, one
would a priori assume a system is vulnerable, and the
burden of proof to the contrary would rest with its
promoters.

John Savard

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Jan 2, 2005, 11:20:56 AM1/2/05
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On Sun, 02 Jan 2005 01:14:12 +0200, Markus Jansson
<seemyh...@katsokotisivuilta.ni> wrote, in part:

>I dont, simply because they havent published them for peer-review

Well, in that case, I don't know what they are, so I wouldn't be able to
tell you if they are secure or not.

John Savard
http://home.ecn.ab.ca/~jsavard/index.html

Gregory G Rose

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Jan 2, 2005, 1:18:50 PM1/2/05
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In article <cr7akj$bsc$1...@phys-news1.kolumbus.fi>,

Markus Jansson <seemyh...@katsokotisivuilta.ni> wrote:
>I dont, simply because they havent published them for peer-review and
>they have made poor crypto before. But I just want to hear a quick
>opinion from the newsgroups most regular and respected contributors. :)

I haven't seen the Tetra algorithms, which means
I'm allowed to comment on them... and please bear
in mind that these are personal comments, not in
any sense on behalf of my employer.

Based on its age and provenance, I would expect
that the TETRA algorithms are multiple-LFSR
nonlinear filter algorithms. The were designed
well before the current algebraic attacks
(Courtois, Armknecht(?sp), Pieprzyk, etc.) and I
think they have a high chance of being
academically broken by this kind of attack.

That said, TETRA restarts the stream frequently,
and unless there's something wrong with its
initialization (possible but unlikely), you'll
never get the data you need to do the
cryptanalysis. So it's probably secure in
practice. But it might not be.

In any case, if you want to send stuff securely
through it, application-layer security (like TLS)
is the only way to go, in any of these systems.

Greg.
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Greg Rose
232B EC8F 44C6 C853 D68F E107 E6BF CD2F 1081 A37C
Qualcomm Australia: http://www.qualcomm.com.au

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