No abstract

Recent research has demonstrated that there is no sharp distinction between passive attacks based on sidechannel leakage and active attacks based on fault injection. Fault behavior can be processed as side-channel information, offering all the benefits of Differential Power Analysis including noise averaging and hypothesis testing by correlation. This paper introduces Differential Fault Intensity Analysis, which combines the principles of Differential Power Analysis and fault injection. We observe that most faults are biased -such as single-bit, two-bit, or three-bit errors in a byte -and that this property can reveal the secret key through a hypothesis test. Unlike Differential Fault Analysis, we do not require precise analysis of the fault propagation. Unlike Fault Sensitivity Analysis, we do not require a fault sensitivity profile for the device under attack. We demonstrate our method on an FPGA implementation of AES with a fault injection model. We find that with an average of 7 fault injections, we can reconstruct a full 128-bit AES key.

Many commercial systems in the embedded space have shown weakness against power analysis based side-channel attacks in recent years. Designing countermeasures to defend against such attacks is both labor intensive and error prone. Furthermore, there is a lack of formal methods for quantifying the actual strength of a countermeasure implementation. Security design errors may therefore go undetected until the side-channel leakage is physically measured and evaluated. We show a better solution based on static analysis of C source code. We introduce the new notion of Quantitative Masking Strength (QMS) to estimate the amount of information leakage from software through side channels. The QMS can be automatically computed from the source code of a countermeasure implementation. Our experiments, based on side-channel measurement on real devices, show that the QMS accurately quantifies the side-channel resistance of the software implementation.

No abstract

No abstract