[Tinyos Core WG] Fwd: CC2420 Security Support Documentation

[Philip Levis]

On Jul 1, 2009, at 11:22 AM, Miklos Maroti wrote:

> Hi Phil,
>
> On Wed, Jul 1, 2009 at 8:16 PM, Philip Levis<pal at cs.stanford.edu>  
> wrote:
>>
>> On Jul 1, 2009, at 11:14 AM, Miklos Maroti wrote:
>>
>>> Hi John,
>>>
>>>> The CC2420SecurityMode is only active for the next AMSend.send  
>>>> command.
>>>> You
>>>> can set different security options for different messages on a per
>>>> message
>>>> basis. The security header is attached when an AMSend is called  
>>>> through a
>>>> SecAMSend interface.
>>>
>>> I find that rather strange in an event driver OS. You CANNOT be sure
>>> that no other module is going to call AMSend in between your calls.
>>
>> If it's sync code, you can be.
>
> Oh, you are completely right, my bad.
>
> Why did we choose with PacketAcknowledgements, PacketLink,
> PacketTimeSync to pass in the message buffer? What is fundamentally
> different with packet  security modes than with other packet options?

Historically, the idea was that you could configure a packet and send  
it later. So those parameters are stored in metadata.

It probably makes sense to keep that programming style here, rather  
than change to the stateful approach.

Phil