
Sliding Right into Information Theory - sctb
http://www.joachim-breitner.de/blog/747-Sliding_Right_into_Information_Theory
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brian_herman__
Could somebody explain this like I am 5 years old?

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scottlocklin
While working on the tail end of a side channel attack paper, the author came
up with a new analytic form for Renyi entropy used in the type of hidden
markov model used in the side channel attack. Pretty solid piece of work.

I am not super familiar with the use of Renyi entropy in HMMs, but it looks
pretty generally interesting; something that can be used to find recurrence
maps in general.

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fizwhiz
Your ELI5 needs an ELI5 :)

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a-dub
They're talking about computing k^m mod p. In the era where you can get a
sense for what operations have taken place based on fingerprints left in the
cache, timing, etc, the algorithms for computing it are ideally designed to be
hardened against it. That is, given knowledge of the sorts of operations that
have taken place, how many bits of the secret that is being computed can be
recovered? They demonstrate that more bits than previously thought can be
practicably recovered from an actual implementation of RSA by using clever
statistical modeling and ideas from information theory.

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fizwhiz
This is much easier to digest, thank you. What's the significance of computing
k^m mod p in this context?

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a-dub
LOL his headings appear to use the same font as David Mackay's excellent free
book on information theory!

[http://www.inference.org.uk/itila/book.html](http://www.inference.org.uk/itila/book.html)

