Key Management

Design of Physical-Layer Key Generation Blocks


A high-level flow of the steps to execute physical-layer key generation is presented in the figure below. To demonstrate this as proof-of-concept in our testbed, we make use of software defined radios from Analog devices in order to access the I/Q samples at the physical-layer of the communicating devices. Note that XBee devices are not flexible for accessing the I/Q samples as we can only modify the packet at the frame level, however, not at the physical-layer level. To execute this functionality, the following tasks are performed sequentially.

  1. The two UEs exchange pilots at regular intervals using their SDRs on the same frequency band

  2. The two UEs collect the I/Q symbols at their receiver store them as part of the advantage distillation phase of key generation

  3. The two nodes then apply a novel consensus algorithm to minimize the mismatch rate between the sequences at their side. To execute this step, they either use the SDRs or may talk to each other using the XBee devices. Since the need for SDRs are only for channel extraction, the rest of the algorithms can be implemented using the XBee devices at the message level.

  4. The two devices finally apply LDPC based reconciliation and then apply a hash function so that identical keys are generated at the two sides.

  5. Subsequently, in the testbed demonstration, an image is communicated from one UE to another through AES, and then displayed on the console so as to prove that the keys generated at the two UEs were identical.


The above functional blocks would be implemented on 5G compliant architecture as well. This has been shown through SDRs on the ISM band only for proof-of-concept.

Sub-blocks needed to execute the key generation phase between two UEs

Related Publications:


  1. J. Harshan, Rohit Joshi and Manish Rao ``Group Secret-Key Generation using Algebraic Rings in Wireless Networks," in IEEE Transactions on Vehicular Technology, Vol. 70, No. 02, pp. 1538--1553, Feb. 2021.

  2. Rohit Joshi and J. Harshan, ``On Opportunistic Selection of Common Randomness and LLR Generation for Algebraic Group Secret-Key Generation," IEEE Vehicular Technology Conference (VTC2021-Spring), Helsinki, 2021.