[Cryptech Tech] Key generation and storage

[Joachim Strömbergson]

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Aloha!

Rob Austein wrote:
> So, again: what's the problem we're trying to solve by moving key 
> generation onto the FPGA?

The discussion Jakob and I had (and why we added this as as a question
in the mail Jakob posted), is if it would be possible to never ever have
secret keys in cleartext outside of the FPGA and thus out of the SW
domain. If there would be a benefit to do so in terms? And if that
benefit would outweigh the added complexity in HW?

Moving the at-rest storage handling from the FPGA to the ARM makes it
easier to increase the size of the storage, handle FLASH wear leveling
etc [1]. As long as the FPGA has the Master Key and handles key wrapping
we should be able to have a clear separation where keys are used and
thus unwrapped, and where they can be efficiently stored. It probably
makes for a simpler and more flexible solution.

Moving the key generation into the FPGA might strengthen the separation,
but would make the FPGA more complex. The question is how bad it would be?

I have done some searches, but not found any good papers describing
complete RSA key generation in FPGAs. Peter, do you know about any
published research into this?


[1] When Jakob and I discussed this our conclusion was that wear
leveling quite probably would not be needed for FLASH memory based key
storage. They are basically never rewritten. But the metadata records
for the keys might be written a bit more often. What makes having the
CPU handling the FLASH storage better is to handle FLASH page access
issues.
- -- 
Med vänlig hälsning, Yours

Joachim Strömbergson - Alltid i harmonisk svängning.
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 Joachim Strömbergson          Secworks AB          joachim at secworks.se
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