2012 Reports :  Cryptology ePrint Archive Forum
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Posted by: ncourtois (IP Logged)
Date: 23 June 2012 18:41

In eprint/2012/338 we read:

"for the first time, we propose a general algebraic attack framework on
the multi-output stream ciphers"

But in fact the authors ignore the most basic literature on the topic:
The following paper specifically covers the scenario with multiple
outputs and provides many useful worst-case bounds on the existence of
such attacks:

Nicolas Courtois:
Algebraic Attacks on Combiners with Memory and Several Outputs,
ICISC 2004, LNCS 3506, pp. 3-20, Springer 2005.
An extended and updated version of this paper is available at


On page 5 we find 4 attack scenarios called S1-S4.

This is highly confusing, because,
please note that a similar notation S12345 was used in the extended version of
Nicolas Courtois, Willi Meier: Algebraic Attacks on Stream Ciphers with
Linear Feedback. Eurocrypt 2003, LNCS 2656, pp. 345-359, Springer.
This is available at [www.nicolascourtois.com]

The notation S12345 is also used in extended slides by Courtois which can be found at

The scenario S5 on page 70 is precisely the attack with multiple outputs (and also for augmented functions).
See also:

Edited 7 time(s). Last edit at 10-Sep-2012 12:46 by ncourtois.

Re: 2012/338
Posted by: ncourtois (IP Logged)
Date: 09 September 2012 11:26

in their paper we read:

"This paper focuses on the LFSR-based multi-output stream
ciphers consisting of a linear feedback shift register (LFSR) and a multioutput filter boolean function"

WHILE my paper covers already a MUCH more general case when also you have internal memory added to the non-linear filter, and when you have 0 memory bits, my framework degrades to the simple case they study here.

The authors claimed to ignore and have promised me to update their paper on 25/06/2012...

However to this day their paper was NOT updated.

I must therefore ask the IACR to withdraw this paper and to blacklist the authors from eprint as perpetrators of serious scientific fraud.

Edited 3 time(s). Last edit at 10-Sep-2012 13:02 by ncourtois.

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