Patch to speed-up LibTomMath

[Peter Turczak]

Hi there,

while working on a quite low-power embedded System (a 68k derivative  
clocked at 166 MHz), I realised that libtommath was simply too slow.  
Just connecting to an ssh-server using dbclient took about 30-40 sec.  
Therefore I adapted the whole dropbear code and libtomcrypt (which  
already comes with an appropriate interface) to use libtomsfastmath,  
which heavily uses fix-precision numbers and assembly.

The patch is nearing its completion, for now a connection using  
dbclient takes about 11 sec, from local commandline to logoff after a  
remote "echo hello". Unfortunately the dropbear server seems to have  
broken while doing m68k assembly speedups, but this should be  
fixable. On an X86 this patch likewise greatly increases the  
performance of all public-key algorithms.

It would be interesting how close Marcos and my approaches regarding  
speedups are under real word conditions, say slow/underpowered/ 
embedded computers like routers, ,,netbooks'', dboxen,etc.

If there is any demand for a pre-alpha release maybe I would put it  
on my webpage for you to download, just let me know.

Best regards,
   Peter

On Dec 17, 2008, at 11:20 PM, bodrato at mail.dm.unipi.it wrote:

> Dear dropbear developers,
>
> I was experimenting with the Toom-Cook multiplication algorithm,  
> for large
> numbers, and I run across LibTomMath. Unfortunately the main  
> project seems
> dead and forgotten, so I searched for an active project using its  
> code and
> I've found Dropbear!
> I patched the 3-way Toom from libtommath with some simple  
> optimizations
> ( http://ln.bodrato.it/FasterToomConvolution_pdf ), now it is
> significantly faster: on my laptop it "obsoletes" the Karatsuba code,
> since it is as fast a Karatsuba for small operands, but faster for  
> bigger
> ones.
> Now the question is: are you interested in the patch?
> (maybe you prefer not to modify an "external and imported" library...)
> In the case you are interested, how should I submit the new files?
>
> Thank you for any answer,
> Marco
>
> -- 
> http://bodrato.it/
>
>
>