With the advent of IoT, crypto-less key establishment protocols exploiting intrinsic channel randomness of physical layer are gaining great interest. These crypto-less protocols are computationally inexpensive and thus suitable for low-power devices. Specifically, they require almost 61 times less energy than for ECDH. However, crypto-less protocols require relatively high time for establishing the secret key (several minutes) as compared to ECDH (few milliseconds).

My question is about the performance benefits of ECDH and physical layer key establishment.

  1. What is an ideal time period for the key establishment? To be specific, for video surveillance applications where normal traffic is very high, how much time should be allowed for the key establishment? Is crypto-less key establishment enables the requisite level of usability?

2.These crypto-less protocols also prone to passive eavesdropping due to the absence of any prior trust. Is some pre-shared secret during deployment a good option for IoT scenarios?

  • $\begingroup$ Question (1) appears to be a question about your what market will tolerate, not about cryptography. Question (2) is too broad to answer. Do you have a specific question about cryptography for a specific application with specific constraints and a specific threat model, or about a specific protocol? $\endgroup$ – Squeamish Ossifrage May 7 '18 at 20:45