Re: HW CRYPTO: rt2500usb

[Ivo van Doorn <ivdoorn@gmail.com>]

On Tuesday 30 December 2008, Ivo van Doorn wrote:
> Hi,
> 
> Currently HW crypto support has been implemented for rt2500usb,
> but has been disabled by default since it only works for TKIP.
> I am currently investigating why WEP and AES are failing, I am currently
> hitting a deadend so I hope somebody else has some suggestions.
> 
> With the current implementation which works for TKIP I noticed that WEP128
> and AES will neither transmit any data after the succesfull association. Upon
> investigation I discovered that below patch was required to make the transmitting
> of frames possible, _but_ none of the frames receive a proper reply from the AP.
> 
> The strange part is that the data length of the frame must be increased by a number
> of bytes depending on the crypto algorithm. From what I gather, the value most likely
> represents the icv_len value from the ieee80211_key structure. The weird part is that
> TKIP apparently does not require this additional length.
> 
> So far I haven't found the legacy driver adding these extra bytes to the length either,
> which sounds a bit suspicious as well.
> 
> Frames caught using wireshark from a second computer look a bit suspicious,
> a ping command from my PC will be received as broadcast frames on wireshark
> with a size of 32 bytes. (I have changed the size of the ping request, but the received
> frames don't change in size)
> 
> I'll try to do some more research later this week, but hopefully somebody has some
> suggestions on where to look for me. :)

Never mind, issue has been fixed. Well at least it is working on WEP 128
but my laptop died before I could test AES. Patch will be send to linux-wireless in
a few minutes.

Ivo