[e2e] Regarding use of Reed-Solomon code in wireless networks

[Debarshi Sanyal]

On 6 May 2015 at 20:14, Detlef Bosau <detlef.bosau at web.de> wrote:

> Am 06.05.2015 um 15:02 schrieb Debarshi Sanyal:
> > Hi Detlef, Khaled,
> >
> > Thanks for sharing your views.
> >
> > For the detection mechanism to work, retransmission must be explicitly
> > switched off (as retransmitting same nonce gives advantage to the
> wormhole
> > attacker).
>
> Even then the problem is to discern a wormhole from noise. Years ago,
> the community discussed the "loss differentiation problem" which
> focussed on the question whether a lost packet was due to congestion or
> due to corruption. In WiFi networks, the question is whether a lost
> packet is due to collision or due to corruption. Disabling
> retransmission in WiFi networks means disabling the MAC scheme. (NB:
> There is no such thing as collision DETECTION in WiFi.)
>

I understand there is a fundamental problem here: corruption or collision.
Independent of the cause, the receiver will attempt to repair the packet.
If it fails, the sender must transmit a fresh nonce.
The unfortunate downside is that if packets are lost due to collisions and
the backoff mechanism of MAC is switched off, collisions will only
increase.

The wormhole is assumed to be passive: it will not corrupt the packet; it
will only tunnel it over a longer distance. This assumption effectively
means only noise can corrupt the packet. Active wormholes are definitely
more difficult to detect.




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