[strongSwan] difference between 'aes128' and 'aes128gcm8' notation in 'esp' cypher algo

[Shahreen Ahmed]

Hello,

Waiting for a feedback on this.

Thanks,
Shahreen


On 17.07.2014 14:23, Shahreen Ahmed wrote:
> Hi all,
> 
> I am trying to use aes-gcm crypto algorithm in my setup where the cpu
> has 'aes' instruction enabled and the relevant drivers are loaded:
> 
> lsmod | grep -e aes -e gcm
> gcm                    10857  0
> aesni_intel            12915  4
> cryptd                  8006  4 ghash_clmulni_intel,aesni_intel
> aes_x86_64              7961  1 aesni_intel
> aes_generic            27609  2 aesni_intel,aes_x86_64
> 
> I compiled Strongswan with --enable-gcm and added the 'gcm' plugin in
> the strongswan.conf file.
> 
> If I use 'aes128gcm8' as 'esp' in ipsec.conf I get poor performance
> (60% less throughput on UDP traffic) than using only 'aes128'.
> 
> My question is :
> 
> 1) with only 'aes128' what integrity algo does it actually use?
> 
> 2) To enable and use 'aes128gcm8' effectively (as expecting better
> throughput) do I need to take any extra steps than the above?
> 
> I tried with using PRF for GCM resulting no improvement.
> 
> Thanks,
> Shahreen