Interesting issues with CCMP

Kyle McMartin kyle
Fri Sep 24 17:08:34 PDT 2004

Hi James,

On Fri, Sep 24, 2004 at 04:28:30PM -0700, James Woo wrote:
> It's a Linksys WAP54g bug. It's not clearing the PwrMgt bit (bit 12) when 
> constructing
> the AAD. You're losing your multicast packets when PwrMgt bit is set. To 
> become bug-compatible,
> change line 818 in hostap_crypt_ccmp.c from
> 	aad[3] = pos[1] & 0xc7; to 	aad[3] = pos[1] & 0xe7;
> and then your problem should go away.


> James Woo
> P.S. Linksys WAP54g has similar CCMP problem with fragmentation too.
> It's clearing the fragment number when constructing the AAD. To verify the 
> problem, you'll
> see no data traffic when fragmentation is enabled (for example, 
> fragmentation = 256).

Ick. I guess I'll have to hope for a firmware upgrade from linksys.

Thanks again,
	Kyle McMartin.

More information about the Hostap mailing list