Effect of encryption on wireless performance?

[tipoo]

How much do WEP or WPA/WPA2 encryption hurt wireless performance? i understand that it varies from router to router, newer ones having nearly zero impact, but some having up to 25%. mine is somewhat oldish (3 years maybe?), its a D-link DI-524. just curious.

 

[Guest]

I think I have detected some improvement in speed when running without encryption on a current Netgear unit. Previously, I was told that encryption slowed down connections (this was on an older Netgear unit).

The difference between WEP and WPA seems to be when you connect, there's more handshaking as the passphrase coding changes each time you connect so more delay.

 

[tipoo]

seems like older routers have to do WPA2 encryption through drivers, adding overhead and slowing down the router. newer ones have specialized chips that offload this task. geuss i'll stick to WPA(1?).

 

[gstefanick]

Tipoo,

GREAT QUESTION...

In fact I did a study for an enterprise customer some time ago and this is what I found (going off memory)


First, most SOHO equipment (AP / CLIENTS) (product you get off the shelf at BestBuy) arent designed with high end processing chips. You also MUST consider its not just the router you need to consider. When your wireless client is sending frames, its must encry them and also decryp them when receiving them. So keep that in mind...

WEP - Very little security over head. Its a static RC4 key which can be 64 or 128 bit.


WPA/TKIP (PSK)- You have to remember there is the authenication and then encryption.

AUTHN-- It uses a 4 way handshake, this process itself should take no more then 100ms and in most cases like 20ms. After the 4 way handshake is complete it.
ENCRYP-- WPA retains the use of RC4 but adds features designed to address the deficiencies in the way that WEP uses the cipher.WPA lengthens the Initialisation Vector (IV) to 48 bits and the master key to 128 bits. Temporal Key Integrity Protocol (TKIP) generates different keys for each client and alters keys for each successive packet.

WPA2/AES (PSK) -- Again uses 4 way handshake. Same time as above. WPA2 uses the Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) protocol, based on the Advanced Encryption Standard (AES) algorithm for authentication and data encryption. TKIP greatly increases the difficulty of intercepting wireless traffic over WEP, but CCMP is more secure than the combination of RC4 and TKIP. Since CCMP requires more processor cycles than RC4, an upgrade to WPA2 may require replacement of APs or client wireless interfaces.

 

[tipoo]

thanks for the great reply...I'm using WPA right now (TKIP) as it seems to have the best security/loss in performance ratio. some dude on another forum warned me NOT to use WPA2 on the DI-524, he said the thing kneels over and restarts. ah, well. its secure enough for me, its just a simple home network. no top secret stuff to see here


ugh, wi-fi is so confusing with KTIP, AES, PSK, EAP, all that jazz.

 

[gstefanick]

Yeah, i know it takes a bit to get under the belt. AES has a lot of overhead. WPA/TKIP you will be fine.

 

[tipoo]

So you think i should stick with TKIP?

 

[gstefanick]

yea, you will be fine.