Conclusions

In this paper, we have presented an extension to our TESLA scheme which provides a solution to the source authentication problem under the assumption that the sender and receiver are loosely time synchronized. The basic TESLA protocol has the following salient properties:

• Low computation overhead. On the order of one MAC function computation per packet for both sender and receiver.
• Low communication overhead. Required is as little as one MAC value per packet. Periodically, the sender also needs to send out the secret keys.
• Perfect loss robustness. If a packet arrives in time, the receiver can verify its authenticity eventually (as long as it receives later packets).

The extensions we propose in this paper feature:

• The basic TESLA scheme provides delayed authentication. With additional information in a packet, we show in this paper how we can provide immediate authentication.
• We reduce the communication overhead when multiple TESLA instances with different authentication delays are used concurrently.
• We derive a tight lower bound on the disclosure delay.
• Harden the sender and the receiver against denial-of-service attacks.