Re: Byte Addressability And Beyond

On Tue, 4 Jun 2024 10:54:27 +0200
Terje Mathisen <terje.mathisen@tmsw.no> wrote:

Michael S wrote:

On Mon, 3 Jun 2024 08:03:53 -0000 (UTC)
Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
 

On Thu, 30 May 2024 18:31:46 +0000, MitchAlsup1 wrote:
 

30 years ago you could say the same thing about encryption. 

>
I don’t think newer CPUs have been optimized for encryption.
Instead, we see newer encryption algorithms (or ways of using
them) that work better on current CPUs. 

 
I think moderate efficiency on CPU, not too low, but not high
either, is a requirement for (symmetric-key) cipher. Esp. when the
key is 128-bit or shorter. 

 
That's correct:
 
CPU efficiency, primarily on the reference 32-bit platform
(PentiumPro 200 MHz) but also on an 8-bit "smart card" implementation
was one of the key requirements for the AES competition.
 
When a group of four programmers (including me) spent a week on
CERN's candidate, we were able to triple the speed, bringing it into
parity with the eventual winner. All the finalists were more or less
the same speed at this point, i.e. able to do full duplex 100 Mbit/s
Ethernet traffic (so around 20 MB/s) on a single thread/core.
 
Terje
 

My point was that for symmetric cipher intended for use with "short"
keys, at least during a phase of standardization, exceptionally high
efficiency on existing CPUs would be considered a defect rather than
advantage.
Not necessarily so for "long" keys, where unbreakability by brute force
is taken for granted.