Secure Broadcasting Over Fading Channels

• Published in: IEEE transactions on information theory Vol. 54; no. 6; pp. 2453 - 2469
• Main Authors: Khisti, A., Tchamkerten, A., Wornell, G.W.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2008; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Broadcasting; Channel state information; Channels; Communication channels; Communication system control; Confidential messages; Councils; Cryptographic protocols; cryptography; Data integrity; Data transmission; Decoding; Degradation; Fading; fading channels; Information security; information-theoretic secrecy; key distribution; Messages; multicasting; multiuser diversity; Optimization; parallel channels; Public key cryptography; Receivers; Strategy; Terminals; Transmission; wiretap channel
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2008.921861

We study a problem of broadcasting confidential messages to multiple receivers under an information-theoretic secrecy constraint. Two scenarios are considered: 1) all receivers are to obtain a common message; and 2) each receiver is to obtain an independent message. Moreover, two models are considered: parallel channels and fast-fading channels. For the case of reversely degraded parallel channels, one eavesdropper, and an arbitrary number of legitimate receivers, we determine the secrecy capacity for transmitting a common message, and the secrecy sum-capacity for transmitting independent messages. For the case of fast-fading channels, we assume that the channel state information of the legitimate receivers is known to all the terminals, while that of the eavesdropper is known only to itself. We show that, using a suitable binning strategy, a common message can be reliably and securely transmitted at a rate independent of the number of receivers. We also show that a simple opportunistic transmission strategy is optimal for the reliable and secure transmission of independent messages in the limit of large number of receivers.