Re: [dm-crypt] bits vs bytes

Arno Wagner
2020-03-31T09:32:58Z

On Tue, Mar 31, 2020 at 08:55:32 CEST, Michael Kjörling wrote:
> On 31 Mar 2020 08:43 +0200, from arno@wagner.name (Arno Wagner):
> > Otherwise you would need to multiply by 8 in a lot of places.
> > And you could also use nibbles (4 bit) words (16 bits),
> > long words (32 bits) or quadwords (64 bits) as "units". The
> > byte is not really specuial.
>
> And let's not forget that at the time when many long-lasting
> encryption algorithms (DES, RSA, anyone?) were being designed, it
> still wasn't an open-and-shut case whether even a digital binary
> computer would represent data in 8-bit chunks or not. Octal was still
> big in the late 1970s.

Hehehe, yes. That would be 3-bit units...

Anyways, while SI has no unit for "information", as it is not
a physical thing, Information Theory typically uses "bit" as
base unit. But there are apparently also people that use "nat"
(base e) and "decimal digit" (base 10) in Information Theory.
So we are fortunate they usually use something binary in the
first place!

Hence "bit" is basically the most common denominator for the
different fields involved and also the most simple one
which nicely satisfies KISS.

For even more confusion:
https://en.wikipedia.org/wiki/Binary_prefix
Not only do SI and IEC disagree, but at least with different
prefixes, apparently JEDEC does something even worse and
redefines existing prefixes!

Regards,
Arno

--
Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@wagner.name
GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718
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