Protecting source code against reverse engineering and theft is an important problem. The goal is to carry out computations using confidential algorithms on an untrusted party while ensuring confidentiality of algorithms. This problem has been addressed for Boolean circuits known as circuit privacy'. Circuits corresponding to real-world programs are impractical. Well-known obfuscation techniques are highly practicable, but provide only limited security, e.g., no piracy protection. In this work, we modify source code yielding programs with adjustable performance and security guarantees ranging from indistinguishability obfuscators to (non-secure) ordinary obfuscation. The idea is to artificially generate misleading' statements. Their results are combined with the outcome of a confidential statement using encrypted . Thus, an attacker must guess' the encrypted selector variables to disguise the confidential source code. We evaluated our method using more than ten programmers as well as pattern mining across open source code repositories to gain insights of (micro-)coding patterns that are relevant for generating misleading statements. The evaluation reveals that our approach is effective in that it successfully preserves source code confidentiality.
Keeping the circuit private while changing any wire value in the circuit has also been investigated @cite_11 . An attack can be detected and data can then be erased.
@cite_11
1663689473 2109894721 2065181350 1998461107
Motivated by the problem of protecting cryptographic hardware, we continue the investigation of private circuits initiated in [16]. In this work, our aim is to construct circuits that should protect the secrecy of their internal state against an adversary who may modify the values of an unbounded number of wires, anywhere in the circuit. In contrast, all previous works on protecting cryptographic hardware relied on an assumption that some portion of the circuit must remain completely free from tampering. We obtain the first feasibility results for such private circuits. Our main result is an efficient transformation of a circuit C, realizing an arbitrary (reactive) functionality, into a private circuit C′ realizing the same functionality. The transformed circuit can successfully detect any serious tampering and erase all data in the memory. In terms of the information available to the adversary, even in the presence of an unbounded number of adaptive wire faults, the circuit C′ emulates a black-box access to C. Trust in reference to integrated circuits addresses the concern that the design and or fabrication of the integrated circuit (IC) may be purposely altered by an adversary. The insertion of a hardware Trojan involves a deliberate and malicious change to an IC that adds or removes functionality or reduces its reliability. Trojans are designed to disable and or destroy the IC at some future time or they may serve to leak confidential information covertly to the adversary. Trojans can be cleverly hidden by the adversary to make it extremely difficult for chip validation processes, such as manufacturing test, to accidentally discover them. This paper investigates the sensitivity of a power supply transient signal analysis method for detecting Trojans. In particular, we focus on determining the smallest detectable Trojan, i.e., the least number of gates a Trojan may have and still be detected, using a set of process simulation models that characterize a TSMC 0.18 μm process. We also evaluate the sensitivity of our Trojan detection method in the presence of measurement noise and background switching activity. A successful detection of the stealthy dopant-level circuit trojan, proposed by at CHES 2013 [1], is reported. Contrary to an assumption made by , dopant types in active region are visible with either scanning electron microscopy SEM or focused ion beam FIB imaging. The successful measurement is explained by an LSI failure analysis technique called the passive voltage contrast [2]. The experiments are conducted by measuring a dedicated chip. The chip uses the diffusion programmable device [3]: an anti-reverse-engineering technique by the same principle as the stealthy dopant-level trojan. The chip is delayered down to the contact layer, and images are taken with 1 an optical microscope, 2 SEM, and 3 FIB. As a result, the four possible dopant-well combinations, namely i p+ n-well, ii p+ p-well, iii n+ n-well and iv n+ p-well are distinguishable in the SEM images. Partial but sufficient detection is also achieved with FIB. Although the stealthy dopant-level circuits are visible, however, they potentially make a detection harder. That is because the contact layer should be measured. We show that imaging the contact layer is at most 16-times expensive than that of a met al layer in terms of the number of images. Malicious tampering of the internal circuits of ICs can lead to detrimental results. Insertion of Trojan circuits may change system behavior, cause chip failure or send information to a third party. This paper presents an information-theoretic approach for Trojan detection. It estimates the statistical correlation between the signals in a design, and explores how this estimation can be used in a clustering algorithm to detect the Trojan logic. Compared with the other algorithms, our tool does not require extensive logic analysis. We neither need the circuit to be brought to the triggering state, nor the effect of the Trojan payload to be propagated and observed at the output. Instead we leverage already available simulation data in this information-theoretic approach. We conducted experiments on the TrustHub benchmarks to validate the practical efficacy of this approach. The results show that our tool can detect Trojan logic with up to 100 coverage with low false positive rates.