EAP-FAST Internal Crypto Libraries take a lot of time

ramprasad.rajendran at wipro.com ramprasad.rajendran
Wed Jan 17 05:56:40 PST 2007

>-----Original Message-----
>From: hostap-bounces+ramprasad.rajendran=wipro.com at shmoo.com 
>[mailto:hostap-bounces+ramprasad.rajendran=wipro.com at shmoo.com]
> On Behalf Of Jouni Malinen
>Sent: Tuesday, January 16, 2007 9:32 PM
>To: hostap at shmoo.com
>Subject: Re: EAP-FAST Internal Crypto Libraries take a lot of time
>On Tue, Jan 16, 2007 at 09:15:19PM +0530, 
>ramprasad.rajendran at wipro.com wrote:
>> I am using the internal TLS and crypto libraries and have 
>> CONFIG_INTERNAL_LIBTOMMATH enabled for bringing down the size.
>> I find that during EAP-FAST authentication, after the server 
>has sent 
>> out a Server Hello Message, the code keeps looping infinitely in the 
>> function s_mp_exptmod in a for(;;) loop. It takes atleast 10 mins 
>> before the function returns :-(
>> Is this behaviour because, the run time memory is not enough or the 
>> processor is pretty slow.
>10 minutes is bit extreme.. One thing to note is that the 
>CONFIG_INTERNAL_LIBTOMMATH version does not include all the 
>optimized bignum algorithms from LibTomMath. In other words, 
>it is expected to take much more CPU than the optimized 
>version (but take less code size). At least in this particular 
>case, I would recommend testing with the full LibTomMath (if 
>at all possible with the memory/flash restrictions) and if the 
>end result is considerable faster, it would be reasonable to 
>merge in some of the more optimized code into libtommath.c.

The AP disassociates after about 2 mins. Would it be possible 
to increase the inactivity timer or something like similar so 
that I can just verify whether it works before I start using 
the faster math libraries.

We have a Cisco Aironet 1100 Series.


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