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FortifyIQ at CHES 2023: Carry-based Differential Power Analysis (CDPA) and its Application to Attacking HMAC-SHA-2

In this paper, FortifyIQ introduces Carry-based Differential Power Analysis (CDPA), a novel methodology that allows for attacking schemes involving arithmetical addition. This methodology is applied to what is believed to be the first published full-fledged attack on HMAC-SHA-2 which does not require a profiling stage.

FortifyIQ provides full mathematical analysis of the method and shows that, under certain assumptions and with a sufficient amount of traces, any key can be revealed. In the experimental part of the paper, FortifyIQ demonstrates a successful application of the attack both in software simulation and on an FPGA board using power consumption measurements.

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Results of FortifyIQ research, described in the paper, show that any implementation of HMAC-SHA-2, even in pure parallel hardware, is vulnerable to side-channel attacks, unless it is adequately protected.
FortifyIQ AES Algorithm
AVA_VAN.5 Evaluation & Validation Summary
SGS Brightsight Common Criteria Laboratory
“Summary. The leakage analysis (Welch t-test) on over 30 million traces did not show statistically significant first- and second-order differences between trace sets with fixed and random inputs. The template-based DPA analysis, on the pseudo-random trace set for the profiling phase (15 million traces) and on a sub-set of 300k fix input traces for matching phase targeting the first-round S-box output, and template attack on ciphertext, did not indicate any potential information leakage.”
“The results for the soft IP presented in the report were obtained on the TOE which is the basic hardware implementation of the soft IP without additional levels of security (e.g. that are present in a secure silicon layout). Therefore the internal strength of the soft IP itself was evaluated. This indicates that the investigated features and parameters of the soft IP implementation should be robust against SCA and fault injection attacks in different implementations including ASIC. Nevertheless, according to the Common Criteria rules, the strength of the final composite product must be evaluated on its own”
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