IEEE Transactions on Wireless Communications

Physical-Layer Secret Key Generation With Colluding Untrusted Relays

Chan Dai Truyen Thai, Jemin Lee, Tony Q. S. Quek

Published Oct 16, 2015• 90 citations

Abstract

In this paper, we propose a physical-layer secret key generation scheme for multiantenna legitimate nodes with the help of multiple untrusted relays, equipped with multiple antennas. The untrusted relays conform to the relaying transmission protocol of legitimate nodes, but they also eavesdrop the confidential information of an legitimate transmitter. The key generation scheme is designed with zero forcing (ZF) and minimum mean square error (MMSE) channel estimators for non-, partially, and fully colluding modes of untrusted relays. Furthermore, we propose a scheme adaptive to channel coherence time. Specifically, to achieve a higher secret key rate (SKR) within the channel coherence time, the number of relay and legitimate nodes' antennas are optimally determined and the most suitable antennas are selected for the key generation. Our results show that the proposed scheme achieves a higher SKR than a prior work, and non- and partially colluding modes provide a higher SKR than the fully colluding mode through the proposed scheme. We also verify that exploiting more antennas of untrusted relays does not always enhance the SKR by showing the existence of the optimal number of antennas of the relays participating in the scheme.

DOI: 10.1109/twc.2015.2491935

Related papers

Physical-layer secret key generation with untrusted relays

Chan Dai Truyen Thai, Jemin Lee, Cheng Chi +1 more

In this paper, we propose a physical-layer secret key generation scheme for multi-antenna legitimate nodes with the help from multiple untrusted relays with single antenna. The relays' actions conform to the rules but they passively eavesdrop the information. Different from most previous key generation schemes, where a key is generated based on a channel coefficient, in the proposed scheme, we use the linear combination of channel coefficients to generate a key. Simulation results show that the rate leaked to the untrusted relays is low and the secret key rate is therefore high. We also point out that the relay communication can achieve higher secret key rate than the direct communication in several distance ranges.

IEEE Globecom Workshops (GC Wkshps)Dec 1, 201410 citations

Physical-Layer Cooperative Key Generation with Correlated Eavesdropping Channels in IoT

Peng Xu, Dongyang Hu, Gaojie Chen

With a massive amount of wireless sensor nodes in Internet of Things (IoT), it is difficult to establish key distribution and management mechanism for traditional encryption technology. Alternatively, the physical layer key generation technology is promising to implement in IoT, since it is based on the principle of information-theoretical security and has the advantage of low complexity. Most existing key generation schemes assume that eavesdropping channels are independent of legitimate channels, which may not be practical especially when eavesdropper nodes are near to legitimate nodes. However, this paper investigates key generation problems for a multi-relay wireless network in IoT, where the correlation between eavesdropping and legitimate channels are considered. Key generation schemes are proposed for both non-colluding and partially colluding eavesdroppers situations. The main idea is to divide the key agreement process into three phases: 1) we first generate a secret key by exploiting the difference between the random channels associated with each relay node and the eavesdropping channels; 2) another key is generated by integrating the residual common randomness associated with each relay pair; 3) the two keys generated in the first two phases are concatenated into the final key. The secrecy key performance of the proposed key generation schemes is also derived with closed-forms.

IEEE International Conference on Internet of Things (iThings) and IEEE Green Computing and Communications (GreenCom) and IEEE Cyber, Physical and Social Computing (CPSCom) and IEEE Smart Data (SmartData)Nov 1, 202013 citations

Cooperative Key Generation in Wireless Networks

Lifeng Lai, Yingbin Liang, Wenliang Kevin Du

The impact of relay nodes on the secret key generation via the physical layer resources is investigated. A novel relay-assisted strategy is proposed to improve the generated secret key rate. The main idea is to exploit the random channels associated with relay nodes in the network as additional random sources for the key generation. This approach is particularly useful when the channels between legitimate nodes change slowly. Four increasingly sophisticated yet more practical scenarios are studied, for which relay-assisted key generation protocols are proposed and are shown to be optimal or order-optimal in terms of the key rate. It is also shown that the multiplexing gain in the key rate scales linearly with the number of relays, which demonstrates that relay-assisted schemes substantially increase the key rate. This is in sharp contrast to scenarios with relays helping information transmission, in which the multiplexing gain does not scale with the number of relays. Furthermore, a cooperative scheme is also proposed in which relays help key generation but the generated keys are kept secure from these relays.

IEEE Journal on Selected Areas in CommunicationsAug 23, 201293 citations

Achievable Rates for Physical-Layer Cooperative Key Generation with Correlated Eavesdropping Channels

Peng Xu, Jun Yang, Gaojie Chen

This paper investigates the cooperative jamming based key generation scheme in a cooperative wireless network, where Alice and Bob aim to generate a secret key (SK) that is secret from Eve and a private key (PK) that is secret from both the relay and Eve, with the assistance of a relay. The correlation between legitimate channels and eavesdropping channels is considered. The SK and PK rates are evaluated based on minimum mean square error (MMSE) and zero forcing (ZF) estimation methods, respectively. The analytical expressions are further simplified with asymptotic forms in the high signal-to-noise ratio (SNR) regime. We demonstrate that the MMSE method is optimal to estimate channels, and the ZF method is asymptotically optimal in the high SNR regime. Moreover, we prove that the double-hop key generation strategy cannot achieve a higher rate than the single-hop strategy. Finally, numerical results validate the analysis and demonstrate that the cooperative jamming based key generation scheme significantly outperforms the traditional pairwise key generation scheme.

IEEE Wireless Communications and Networking ConferenceApr 21, 20242 citations

PHY-based cooperative key generation in wireless networks

Lifeng Lai, Yingbin Liang, Wenliang Kevin Du

The impact of relay nodes on the secret key generation via the physical layer resources is investigated. A novel relay-assisted strategy is proposed to improve the generated secret key rate. The main idea is to exploit the random channels associated with relay nodes in the network as additional random sources for the key generation. This approach is particularly useful when the channels between legitimate nodes change slowly. Three increasingly sophisticated yet more practical scenarios are studied, for which relay-assisted key generation protocols are proposed and are shown to be optimal or order-optimal in terms of the key rate. It is also shown that the presence of relay node increases the multiplexing gain. This is in sharp contrast to scenarios with relay helping information transmission, in which the relay node does not increase the multiplexing. Furthermore, a cooperative scheme is also proposed in which relays help key generation but the generated keys are kept secure from these relays.

Allerton Conference on Communication, Control, and ComputingSep 1, 201117 citations

Cooperative Jamming-Based Physical-Layer Group Secret and Private Key Generation

Shiming Fu, Tong Ling, Jun Yang +1 more

This paper explores physical layer group key generation in wireless relay networks with a star topology. In this setup, the relay node plays the role of either a trusted or untrusted central node, while one legitimate node (Alice) acts as the reference node. The channel between the relay and Alice serves as the reference channel. To enhance security during the channel measurement stage, a cooperative jamming-based scheme is proposed in this paper. This scheme allows the relay to obtain superimposed channel observations from both the reference channel and other relay channels. Then, a public discussion is utilized to enable all nodes to obtain estimates of the reference channel. Subsequently, the legitimate nodes can agree on a secret key (SK) that remains secret from the eavesdropper (Eve), or a private key (PK) that needs to be secret from both the relay and Eve. This paper also derives the lower and upper bounds of the SK/PK capacity. Notably, it demonstrates that there exists only a small constant difference between the SK/PK upper and lower bounds in the high signal-to-noise ratio (SNR) regime. Simulation results confirm the effectiveness of the proposed scheme for ensuring security and efficiency of group key generation.

EntropySep 4, 20241 citation