[45153] in Cypherpunks
Re: Timing Cryptanalysis Attack
daemon@ATHENA.MIT.EDU (Tom Weinstein)
Mon Dec 11 05:23:21 1995
Date: Mon, 11 Dec 1995 02:07:49 -0800
From: Tom Weinstein <tomw@netscape.com>
To: cypherpunks@toad.com
Eric Young wrote:
>
> I for one will probably add a flag for conditional compilation of my
> bignumber library so that it will take constant time. This may be a
> %10 slow down (using small windows exponentiation) which is trivial
> compared to the %30 speedup I will probably get when I implement a
> faster mod function :-).
Careful. Even if you can make the number of executed instructions the
same, you still have to worry about timing differences due to branches
and the way the hardware multiplier handles different operands.
--
Sure we spend a lot of money, but that doesn't mean | Tom Weinstein
we *do* anything. -- Washington DC motto | tomw@netscape.com
