Re: [ISS] Block Chipers Slides

[Giuseppe Bianchi < >]

Ahi! Marco removed the best slide of the pack (here attached again)
which basically says that all modes are (more or less) OK EXCEPT ECB!!

ECB, as Marco will tell you today, should not ve considered a mode, but
it is just a completely insecure approach which should not have been
even named in my opinion!! Indeed, I believe the crypto community made a
BIG error in calling it a "mode" and giving it an acronym, as non expert
people, when seeing the acronym EBC, may think to something meaningful
and may not realize it is just the most stupid thing you may ever do!

In fact too often we see recurring questions (and enjoy some relevant
nonsense comments/answers...) such as:
https://crypto.stackexchange.com/questions/225/should-i-use-ecb-or-cbc-encryption-mode-for-my-block-cipher/226
which suggest that "normal" persons may get badly confused!

Which brings me back to the rationale behind the attached slide (Marco
please re-include it!!): even if you do NOT understand what are such
listed modes (e.g. OFB or XTS are arguably less common than CBC or CTR,
at least in networking!), they at least are all (well, almost all - see
note!) meaningful construction whereas ECB is NOT, as it just means: no
block chaining at all! In other words, whenever you will see ECB in a
configuration, raise a super, super red flag, you have a SERIOUS
security problem!!!

Have a good lecture, and greetings from remote!

GB


technical note: XEX is also bad for the same reasons of ECB, see
wikipedia to understand why. Unfortunately I was not the creator of such
beautiful slide (I'd have in fact also removed XEX from the "good" modes).


Il 16/10/2019 19:54, Marco Spaziani Brunella ha scritto:
> Dear Students;
> You can find attached the slides of today (and tomorrow) lecture.
> See you tomorrow;
> *Marco Spaziani Brunella*
> CNIT Researcher @ University of Rome Tor Vergata
> E // 
> 
 
> <mailto:
 >
> A // Via Del Politecnico 1, 00133 Rome, Netprog Lab
> <https://maps.google.com/?q=Via%20Del%20Politecnico%201%2C%2000133%20Rome%2C%20Netprog%20Lab>
>

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