Re: [libmicrohttpd] HTTPS delay

[Christian Grothoff]

On 10/30/2011 05:16 PM, Avner Flesch wrote:
> Hi,
>
> I am developing simple secured HTTP (HTTPS) server for embedded system.
> It seems that the delay is rather long - for example ~230 KB file delay
> is almost 6 seconds.
> Is there a way to speed it up?

On an embedded system, I suspect the main contributor to latency is CPU 
time for the cryptographic operations (you didn't say what kind of 
embedded system, so it's hard for me to say if 6s is good or bad).

You could configure MHD to use different (faster) ciphers, which may 
give you significant performance improvements (if CPU speed is the 
problem). Google's choices for HTTPS might be a good starting point.

Changing the default cipher suite in MHD is done using 
MHD_OPTION_HTTPS_PRIORITIES followed by a string specifying the ciphers 
(see 'gnutls_priority_init' documentation for the format of that string).

Other than that, there is little you can do: HTTPS is slow, and I'm 
generally pretty sure that MHD and GNUtls are about as fast as they can 
be (so switching to a different HTTP(S) server would also most likely 
not help you --- unless that server uses a different cipher suite by 
default, and in that case you could just use the option I gave above).

Happy hacking!

Christian