Tinc power consuption

[Guus Sliepen]

On Wed, Apr 24, 2013 at 09:46:04AM +0200, Saverio Proto wrote:

> Guus can you tell me if tinc uses openssl and AES algorithm ? (it is
> realted to power consumption)

The manual can tell you that tinc 1.0.x indeed uses OpenSSL, but it uses
Blowfish by default. However, you can switch to AES using the Cipher option.

In tinc 1.1, if you enable the new protocol, AES is the default.

> if yes some computers have a special hardware chip to make AES in
> hardware, and might be the cause of power consumption ?
> http://en.wikipedia.org/wiki/AES_instruction_set
> 
> try cat /proc/cpuinfo | grep aes
> 
> if there is the aes flag then you are doing probably aes in hardware
> in openssl is compiled correctly to do this.
> when you use this chip you might expect a bigger power consumption ?

You would expect a lower power consumption if your CPU supports AES
instructions, because otherwise OpenSSL will use less efficient instructions.

> read this paper, they do something else but they describe the SSL AES
> stuff in detail
> http://staff.science.uva.nl/~delaat/rp/2012-2013/p08/report.pdf
> 
> moreover reading this paper could help to make tinc faster :)

I do not see so much in this paper that could be applied to tinc. Of course, if
you have hardware that OpenSSL can take advantage of, this will indeed speed
things up. And if tinc would use multiple threads that would help too (on
multi-core systems), but that is not so trivial to implement.

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
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