Yin and Madria [9] describe an approach for black hole
mitigation that works by introducing authorization and cryptography
into the routing protocol. This is a valuable contribution
to solving the problem, but it assumes that the
cryptographic keys used by the nodes won’t get in the hands
of an attacker. Papadimitratos and Haas [10] also propose a
secure routing scheme which they argue mitigates the effects
of routing misbehaviour. This scheme also uses cryptographic
methods to ensure that spurious route responses are rejected by
recipients. Given that sensor nodes are usually small and out of
the reach of the network operator, theft and reverse-engineering
is a real possibility and it does not suffice to assume that
the cryptographic keys will always be secret; thus we require
alternate methods to protect against black hole attacks.