[Libre-soc-bugs] [Bug 770] Discussion and Finalisation of Which Cryptographic Primitives to Implement

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=770

--- Comment #10 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Jacob Lifshay from comment #9)

> there *is* a point,

it's always a good idea to read ahead, all messages, in full.
i already worked that out :)

> run much faster 

please understand and accept that the purpose of the exercise,
under this Grant, is *not* processor speed, it is instruction
count reduction and thus efficiency and power reduction.

speed is an arbitrary factor based on a direct near-linear
relationship with how much back-end silicon is thrown at the
problem, whereas power consumption is not.

> is very highly significant

anyone may throw more silicon down and claim "it's significant".
every datasheet for hard macros also contains power consumption
figures and these are what is much more critical.

SV being completely abstract and an architecturally independent
ISA the only thing we can possibly claim right across the board
of all possible microarchitectures is that power consumption
is reduced as a direct result of the reduction in instruction
count.

> nearly everything i described in comment #5 was talking about poly1305, not
> chacha. those are all 320 and 192-bit bigint ops (rounded up to nearest
> multiple of 64-bits) that svp64 + bigint definitely accelerates.

ok.  i needed to know that.  i have (had) no idea what poly1305 is,
and it would be helpful to have crossreferences (comment 0) to reference
code, and so on, yeh?

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