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Logic encryption is a powerful hardware protection technique that uses extra key inputs to lock a circuit from piracy or unauthorized use. The recent discovery of the SAT-based attack with Distinguishing Input Pattern (DIP) generation has rendered all traditional logic encryptions vulnerable, and thus the creation of new encryption methods. However, a critical question for any new encryption method is whether security against the DIP-generation attack means security against all other attacks. In this paper, a new high-level SAT-based attack called SigAttack has been discovered and thoroughly investigated. It is based on extracting a key-revealing signature in the encryption. A majority of all known SAT-resilient encryptions are shown to be vulnerable to SigAttack. By formulating the condition under which SigAttack is effective, the paper also provides guidance for the future logic encryption design.

Cyclic logic encryption is newly proposed in the area of hardware security. It introduces feedback cycles into the circuit to defeat existing logic decryption techniques. To ensure that the circuit is acyclic under the correct key, CycSAT is developed to add the acyclic condition as a CNF formula to the SAT-based attack. However, we found that it is impossible to capture all cycles in any graph with any set of feedback signals as done in the CycSAT algorithm. In this paper, we propose a behavioral SAT-based attack called BeSAT. Be-SAT observes the behavior of the encrypted circuit on top of the structural analysis, so the stateful and oscillatory keys missed by CycSAT can still be blocked. The experimental results show that BeSAT successfully overcomes the drawback of CycSAT.

Logic encryption has attracted much attention due to increasing IC design costs and growing number of untrusted foundries. Unreachable states in a design provide a space of flexibility for logic encryption to explore. However, due to the available access of scan chain, traditional combinational encryption cannot leverage the benefit of such flexibility. Cyclic logic encryption inserts key-controlled feedbacks into the original circuit to prevent piracy and overproduction. Based on our discovery, cyclic logic encryption can utilize unreachable states to improve security. Even though cyclic encryption is vulnerable to a powerful attack called CycSAT, we develop a new way of cyclic encryption by utilizing unreachable states to defeat CycSAT. The attack complexity of the proposed scheme is discussed and its robustness is demonstrated.

The high cost of IC design has made chip protection one of the first priorities of the semiconductor industry. Although there is a common impression that combinational circuits must be designed without any cycles, circuits with cycles can be combinational as well. Such cyclic circuits can be used to reliably lock ICs. Moreover, since memristor is compatible with CMOS structure, it is possible to efficiently obfuscate cyclic circuits using polymorphic memristor-CMOS gates. In this case, the layouts of the circuits with different functionalities look exactly identical, making it impossible even for an inside foundry attacker to distinguish the defined functionality of an IC by looking at its layout. In this paper, we propose a comprehensive chip protection method based on cyclic locking and polymorphic memristor-CMOS obfuscation. The robustness against state-of-the-art key-pruning attacks is demonstrated and the overhead of the polymorphic gates is investigated.

Process variation is the dominating factor for performance degradation in modern IC chips. The conventional guard-band design methodology leads to significant performance penalty. This paper utilizes an emerging non-volatile resistive device, memristor, with timing violation detectors to dynamically achieve local recovery from timing violation during the runtime, eliminating the necessity of testing phase. It develops a systematic self-tuning mechanism that globally adjusts the clock skew scheduling to compensate the timing violation, and determines the tunability of the memristor-based self-tunable circuits. It also proposes an algorithmic memristor placement across the clock tree to balance the tradeoff between hardware cost and system tunability. Experimental results show that our approach can improve the yield from 90% to 98% with only 4% overhead in average.

Due to the increasing complexity of design process, outsourcing, and use of third-party blocks, it becomes harder and harder to prevent Trojan insertion and other malicious design modifications. In this paper, we propose to deploy security invariant as carried proof to prevent and detect Trojans and malicious attacks and to ensure the security of hardware design. Non-interference with down-grading policy is checked for confidentiality. Contrary to existing approaches by type checking, we develop a method to model-check a simple safety property on a composed machine. Down-grading is handled in a better way in model-checking and the effectiveness of our approach is demonstrated on various Verilog benchmarks.

"This paper examines the exilic experience and nomadic discourse in the lives and works of Gao Xingjian and Ma Jian, two prominent literary figures who have lived outside China since the late 1980s....Their exilic writing provides new source material for the study of literary exile and nomadism at the turn of the 21st century."

The article examines the social and political uses of the Chinese popular media in promoting the market economy and reforming national subjectivity through the production and promotion of the TV documentary Shanxi Merchants.

(The Chinese film tradition was) a sacred hall (baodian), an orthodox place strictly guarded by professionally trained third and fourth generation filmmakers. The fifth generation didn't enter thro...

This paper explores the discourse of cultural nationalism and its recent articulation in historical TV dramas (Lishi ju): TV serials set in the Chinese imperial past and depicting court politics and the private lives of imperial families. First, I briefly survey the recent resurgence of historical drama on the TV screen, especially comparing two different ways of representing history: “history light” (xishuo) and “history orthodox” (zhengju). While history light, a new genre strongly influenced by the costume dramas imported from Hong Kong and Taiwan, emphasizes the entertainment values of popular culture and adopts a postmodern attitude towards history, history orthodox renews the pedagogical tradition and the moralistic narrative of historical drama in modern China since the May Fourth enlightenment movement. I then focus on TV dramas in the history orthodox mode and their ideological messages, examining two representative works by Hu Mei: Yongzheng Dynasty (Yongzheng wangchao, 1999) and The Great Emperor Wu of Han (Hanwu dadi, 2005). While drawing attention to the various narrative strategies, intertextualities and audio-visual styles employed in these dramas to represent the glorious national history and portray a strong leader (the emperor) as national hero, I also provide a contextual analysis of the production and circulation of these two dramas as well as the critical and media response to them, to reveal the social agencies and social formation of these dramas behind the screen. I suggest that the revisionist reframing of the past in historical TV drama reflects a new nationalist historical consciousness and cultural identity borne out of China’s rapid rise and aspirations to become an economic and political superpower.