[Cryptography] [Crypto-practicum] Justify the sequence of operations in CTR mode.

[Tom Mitchell]

On Tue, Feb 16, 2016 at 1:42 PM, Ron Garret <ron at flownet.com> wrote:

>
> On Feb 16, 2016, at 11:03 AM, Ryan Carboni <ryacko at gmail.com> wrote:
>
> > Why not use single-key Even-Mansour-like construction?
> >
> > Ciphertext = E( E(CTR) XOR plaintext)) XOR E(CTR)
> >
> > Costs only two encryptions, both parallelizable,
>
> I don’t think so.  You have an iterated encryption E(E(…)).  That looks
> like a serial dependency to me.


Not parallel but pipeline, there will be another block.  Multiple
filesystems are
common too.
So not totally SIMD friendly but SMP friendly up to a processor count where
the block size abuses cache.   The individual encryptions may be very
parallel
and farmed out to SIMD, vector  or special purpose hardware blocks.



-- 
  T o m    M i t c h e l l
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