DoS on the Key Chain

Another DoS attack is specific to how the TESLA receiver reconstructs the key chain. If an attacker could fool a receiver to believe that a packet was sent out far in the future, and the receiver would try to verify the key disclosed in the packet by applying the pseudo-random function until the last committed key chain value. This attack can be easily prevented by checking that the packet interval is less or equal the latest interval that the sender can possibly be in. For an incoming packet sent in interval $I$_j, the receiver can verify if the interval $I$_j is not in the future, i.e. if the sender can already be in that interval. The verification condition is that $I$_j < (t_i - T₀) / T_int , where $t$_i is an upper bound on the sender's time that the receiver computes at the arrival of the packet.