WPA2-PSK safty

Hi,

I'm wondering about WPA2 safety in the scenario of a preshared key (PSK).
I'm aware that the protocol is safe by today's knowledge if they key is kept
secure.
But what if I share the key with another person to enable that person to use
my AP. Will that break confidentiality of my communication with the AP?
The AES encryption key is derived from the PSK in some form of handshake. I
want to know now if someone else can obtain that key by capturing the
handshake and knowing the PSK?

Thanks, Thorsten

Thorsten Tarrach wrote:
>
> I'm wondering about WPA2 safety in the scenario of a preshared key
> (PSK). I'm aware that the protocol is safe by today's knowledge if they
> key is kept secure.
> But what if I share the key with another person to enable that person to
> use my AP. Will that break confidentiality of my communication with the AP?
> The AES encryption key is derived from the PSK in some form of
> handshake. I want to know now if someone else can obtain that key by
> capturing the handshake and knowing the PSK?

That's a very good question, and one for which you can get a pretty
definitive answer from the good people at sci.crypt.

My own gut feeling is that if they sniff your handshake packets AND they
have the PSK, they can decrypt the random session key, but I may well be
talking balls. You need to ask the professionals.