info required urgently

[Matt Johnston]

On Thu, May 21, 2009 at 06:20:59PM +0530, Sourav Chakraborty wrote:
> We are trying to use Dropbear as a base to evaluate if we can build a sshv2 server with minimal requirements and whose footprint would be ~70kB.
> Can you please refer us to some diagrammatic representation of ssh v2 server 
> architecture and Dropbear architecture documentation(which will help us in 
> understanding the codebase)?

As I already told you, none exists that I know of. I'm not
going to produce any at the moment.

Buliding on Ubuntu i386 9.04 with the attached options.h, using the
options documented in SMALL and:

export CFLAGS="-ggdb -Os -Wall -ffunction-sections -fdata-sections"
export LDFLAGS="-Wl,--gc-sections"
./configure --disable-zlib
make PROGRAMS=dropbear
strip -o dropbear.strip dropbear

I get a 83 kB binary. Try running 

objdump -t dropbear|grep -v UND|cut -c 16-|sort |less

and you'll get a sorted list of functions and sizes. You
could add down the bottom of libtommath/tommath_class.h
#undef BN_FAST_MP_INVMOD_C
#undef BN_MP_EXPTMOD_FAST_C
and it should save a few more kB.

If binary size is your only requirement, running UPX on it
will get it to <40kB ;)

Matt
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