Perfect Secrecy in Bidirectional Relaying (Joint work with Shashank V. and Navin Kashyap at IISc, Bangalore)

Andrew Thangaraj

Department of Electrical Engineering
Indian Institute of Technology (IIT),
Madras, India

Abstract:

The XOR of two bits is independent of each one of them. This fact was used in the classical one-time pad to get perfect secrecy. An interesting question is whether perfect secrecy arises in a similar fashion in other scenarios. Specifically, we consider compute-and-forward in bidirectional relaying, where a relay node wants to compute the XOR of two bits from two other nodes. In this scenario, the two nodes modulate their individual bits to integers and transmit them simultaneously. These integers get summed at the relay node. Is it possible to design the modulation such that the sum of the integers is independent of each of the bits? Can the sum still convey the XOR of the bits to the relay node? Can such a modulation be power-limited? We answer these questions in the affirmative and establish an achievable rate using lattice codes.

Biography:

Andrew Thangaraj received the B.Tech. degree in electrical engineering from Indian Institute of Technology (IIT), Madras, India, in 1998, and the Ph.D. degree in electrical engineering from Georgia Institute of Technology, Atlanta, in 2003. He was a Post doctoral Researcher at the GTL-CNRS Telecommunications Laboratory at Georgia Tech Lorraine, Metz, France, from August 2003 to May 2004. From June 2004, he has been with the Department of Electrical Engineering, IIT Madras, where he is currently an Associate Professor. His research interests are in coding theory, information theory and physical layer security. He is currently serving as Editor (coding theory and information-theoretic secrecy) for the IEEE Transactions on Communications.