Recommended key size for life long key

Robert J. Hansen rjh at
Mon Sep 9 09:42:16 CEST 2013

On 9/9/2013 3:03 AM, John Clizbe wrote:
> Several minutes to verify a signature makes such large key sizes non-starters.
> Folks using a baseline of a 1GHz cellphone seem to have no idea of the
> lifetimes involved in MIL-SPEC equipment. I'm sure there are some 1 MIPS VAX
> 11/780s still in military service somewhere. /MAYBE/ the 233Mhz hardened
> Pentium chips have been decommissioned by now.

As a data point on that one: the 80386 production line shut down in 2007
after 22 years of production.  It ran at a top speed of 25MHz, but was
more frequently undervolted to enhance lifetime at the cost of reducing
it to 16MHz.  Today it's still a commonly embedded processor.

For those who wonder why the 386 has survived even into the present day,
it mostly has to do with legacy support and recertification costs.  If
you have a piece of Assembly from '86 that works just fine and which you
paid a lot of money to develop and get certified for use in a certain
environment running on x86 hardware, you will probably be very reluctant
to hire the developers, pay for the re-engineering expense, and pay for
the recertification expense, in order to get your application to run on
a modern-day StrongARM.  The embedded 80386 may be slow and antiquated,
but it's *cheap*, and lets you leverage your existing resources.

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