Improving the Efficiency of Thermal Covert Channels in Multi-/many-core Systems
Zijun Long1,a, Xiaohang Wang1,b, Yingtao Jiang2, Guofeng Cui1,c, Li Zhang1,d and Terrence Mak3,4
1South China University of Technology, Guangzhou, China
a201530612446@mail.scut.edu.cn
bxiaohangwang@scut.edu.cn
c201430610429@mail.scut.edu.cn
d201721045909@mail.scut.edu.cn
2University of Nevada, Las Vegas, USA
yingtao.jiang@unlv.edu
3University of Southampton, UK
tmak@ecs.soton.ac.uk
4Guangzhou, China
ABSTRACT
In many-core chips seen in mobile computing, data center, AI, and elsewhere, thermal covert channels could be established to transmit data (e.g., passwords), supposedly to be kept secret and private. Effectiveness of a thermal covert channel, measured by its transmission rate and bit error rate (BER), is so much dependent on the thermal noise=interference imposed on the channel. In this paper, we present a few techniques to improve the capacity of thermal covert channel by overcoming the thermal interference. In particular, data in a thermal covert channel are encoded and represented following a new thermal signaling scheme where logic value, 0 or 1, modules the thermal signals duty cycle. Next, we show in this study that proper selection of transmission frequency can significantly minimize thermal interference. In addition, we propose a robust end to end communication protocol for reliable communications. Our experiments have confirmed that, compared to an existing thermal covert channel attack [1] [2], a thermal covert channel enhanced with all the improvements proposed in this study is seeing significant BER reduction (by as much as 75%), and transmission rate boost (by more than threefold). Building such a strong thermal covert channel is the key step towards developing robust defense and countermeasures against information leaking over thermal covert channel.
