Numerical Simulation on Dynamic Behavior of a Cold-Formed Steel Framing Building Test Model

A nonlinear dynamic numerical simulation on seismic behavior of a two-story cold-formed steel framing building full-scale shaking table test model was carried out by the way of from components to integral structure. Firstly, refined numerical model of shear wall was established, and restoring force models of screw connections between the framing and sheathings were integrated into the numerical model of shear wall. The refined numerical model of shear wall was verified by tests. Secondly, based on refined numerical model of shear wall and modified exponential “Foschi” skeleton curve, uniform restoring force skeleton curves of two typical shear walls of the shaking table test model were obtained. Then, a simplified numerical model of shear wall was proposed. Finally, a dynamic numerical model of cold-formed steel framing building was established based on the simplified shear wall model and assumption of rigid diaphragm, and nonlinear dynamic analysis was carried out. The results of numerical simulation agreed well with the tests, which indicated that the numerical model of integral buildings can factually reflect the dynamic behavior of cold-formed steel framing building

Double DIP: Re-Evaluating Security of Logic Encryption Algorithms

Logic encryption is a hardware security technique that uses extra key inputs to lock a given combinational circuit. A recent study by Subramanyan et al. shows that all existing logic encryption techniques can be successfully attacked. As a countermeasure, SARLock was proposed to enhance the security of existing logic encryptions. In this paper, we re- evaluate the security of these approaches. A SAT-based at- tack called Double DIP is proposed and shown to success- fully defeat SARLock-enhanced encryptions

Rescuing Logic Encryption in Post-SAT Era by Locking & Obfuscation

The active participation of external entities in the manufacturing flow has produced numerous hardware security issues in which piracy and overproduction are likely to be the most ubiquitous and expensive ones. The main approach to prevent unauthorized products from functioning is logic encryption that inserts key-controlled gates to the original circuit in a way that the valid behavior of the circuit only happens when the correct key is applied. The challenge for the security designer is to ensure neither the correct key nor the original circuit can be revealed by different analyses of the encrypted circuit. However, in state-of-the-art logic encryption works, a lot of performance is sold to guarantee security against powerful logic and structural attacks. This contradicts the primary reason of logic encryption that is to protect a precious design from being pirated and overproduced. In this paper, we propose a bilateral logic encryption platform that maintains high degree of security with small circuit modification. The robustness against exact and approximate attacks is also demonstrated

A Comparative Investigation of Approximate Attacks on Logic Encryptions

Logic encryption is an important hardware protection technique that adds extra keys to lock a given circuit. With recent discovery of the effective SAT-based attack, new enhancement methods such as SARLock and Anti-SAT have been proposed to thwart the SAT-based and similar exact attacks. Since these new techniques all have very low error rate, approximate attacks such as Double DIP and AppSAT have been proposed to find an almost correct key with low error rate. However, measuring the performance of an approximate attack is extremely challenging, since exact computation of the error rate is very expensive, while estimation based on random sampling has low confidence. In this paper, we develop a suite of scientific encryption benchmarks where a wide range of error rates are possible and the error rate can be found out by simple eyeballing. Then, we conduct a thorough comparative study on different approximate attacks, including AppSAT and Double DIP. The results show that approximate attacks are far away from closing the gap and more investigations are needed in this area

Vulnerability and Remedy of Stripped Function Logic Locking

Stripped Function Logic Locking (SFLL) as the most advanced logic locking technique is robust against both the SAT-based and the removal attacks under the assumption of thorough resynthesis of the stripped function. In this paper, we propose a bit-coloring attack based on our discovery of a critical vulnerability in SFLL. In fact, we show that if only one protected input pattern is discovered, then the scheme can be unlocked with a polynomial number of queries to an activated circuit. As a remedy to this vulnerability, we also propose a provably secure general function that deregularizes the relation between the protected input patterns and the secret key. The mathematical proofs as well as the experiments confirm both the polynomiality of the bit-coloring attack on standard SFLL and the exponentiality of similar attacks on SFLL with general function

SAT-based Bit-flipping Attack on Logic Encryptions

Logic encryption is a hardware security technique that uses extra key inputs to prevent unauthorized use of a circuit. With the discovery of the SAT-based attack, new encryption techniques such as SARLock and Anti-SAT are proposed, and further combined with traditional logic encryption techniques, to guarantee both high error rates and resilience to the SAT-based attack. In this paper, the SAT-based bit-flipping attack is presented. It first separates the two groups of keys via SAT-based bit-flippings, and then attacks the traditional encryption and the SAT-resilient encryption, by conventional SAT-based attack and by-passing attack, respectively. The experimental results show that the bit-flipping attack successfully returns a circuit with the correct functionality and significantly reduces the executing time compared with other advanced attacks

SigAttack: New High-level SAT-based Attack on Logic Encryptions

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 Locking and Memristor-based Obfuscation Against CycSAT and Inside Foundry Attacks

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

BeSAT: Behavioral SAT-based Attack on Cyclic Logic Encryption

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. BeSAT 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

Effects of Surgery on Prognosis of Young Women With Operable Breast Cancer in Different Marital Statuses: A Population-Based Cohort Study

BackgroundThe influence of surgical approaches [including mastectomy, breast-conserving therapy (BCT) and post-mastectomy breast reconstruction (PMBR) on prognosis of young women (<40 years old) with operable breast cancer has not been determined yet, and this might vary in patients with different marital statuses. Therefore, we aimed to investigate the effect of surgery on survival outcomes for young women with operable breast cancer in different marital statuses.MethodsWe used the Surveillance, Epidemiology, and End Results (SEER) database to identify young women with operable breast cancer between 2004 and 2016, who underwent mastectomy, BCT or PMBR. We assessed overall survival (OS) and breast cancer-specific survival (BCSS) using the Kaplan–Meier method and hazard ratios using multivariate Cox proportional hazard regression.ResultsCompared to mastectomy, both of BCT and PMBR conferred better OS (BCT: HR = 0.79, 95%CI: 0.69–0.90, p <0.001; PMBR: HR = 0.70, 95%CI: 0.63–0.78, p <0.001) and BCSS (BCT: HR = 0.79, 95%CI: 0.69–0.91, p = 0.001; PMBR: HR = 0.73, 95%CI: 0.65–0.81, p <0.001), but there was no significant difference of survival between BCT and PMBR group. The survival benefit of BCT compared to mastectomy remained significant in unmarried young women (OS: HR = 0.68, 95%CI: 0.55–0.83, p <0.001; BCSS: HR = 0.69, 95%CI: 0.56–0.86, p = 0.001) but not in the married (OS: HR = 0.89, 95%CI: 0.75–1.05, p = 0.177; BCSS: HR = 0.89, 95%CI: 0.75–1.05, p = 0.161), while no matter married or not, PMBR group had better OS and BCSS than mastectomy group but not BCT group.ConclusionBoth of BCT and PMBR had improved survival compared to mastectomy for young women with operable breast cancer. The survival benefit of BCT compared to mastectomy remained significant in unmarried patients but not in married patients