Enhancing non-profiled side-channel attacks by time-frequency analysis

Side-channel analysis(SCA)has become an increasing important method to assess the physical security of cryptographic systems.In the process of SCA,the number of attack data directly determines the performance of SCA.With sufficient attack data,the adversary can achieve a successful SCA.However,in reality,the cryptographic device may be protected with some countermeasures to limit the number of encryptions using the same key.In this case,the adversary cannot use casual numbers of data to perform SCA.The performance of SCA will be severely dropped if the attack traces are insufficient.In this paper,we introduce wavelet scatter transform(WST)and short-time fourier transform(STFT)to non-profiled side-channel analysis domains,to improve the performance of side-channel attacks in the context of insufficient data.We design a practical framework to provide suitable parameters for WST/STFT-based SCA.Using the proposed method,the WST/STFT-based SCA method can significantly enhance the performance and robustness of non-profiled SCA.The practical attacks against four public datasets show that the proposed method is able to achieve more robust performance.Compared with the original correlation power analysis(CPA),the number of attack data can be reduced by 50–95%.

Enhanced sulfide chemisorption by conductive AI-doped ZnO decorated carbon nanoflakes for advanced Li-S batteries

Lithium-sulfur batteries have attracted significant attention recently due to their high theoretical capacity, energy density and cost effectiveness. However, sulfur cathodes suffer from issues such as shuttle effects, uncontrollable deposition of lithium sulfides species, and volume expansion of sulfur, which result in rapid capacity fading and low Coulombic efficiency. In recent years, metal-oxide nanostructures have been widely used in Li-S batteries, owing to their effective inhibition of the shuttle effect and controlled deposition of lithium sulfide. However, the nonconductive metal-oxides used in Li-S batteries suffer from extra diffusion process, which slows down the electrochemical reaction kinetics. Herein, we report the synthesis of carbon nanoflakes decorated with conductive aluminium-doped zinc oxide （AZO@C） nanoparticles, through a facile biotem- plating method using kapok fibers as both the template and carbon source. A sulfur cathode based on the AZO@C nanocomposites shows better electrochemical performance than those of cathodes based on ZnO and A1203 with poor conductivity, with a stable capacity of 927 mAh.g-1 at 0.1C （1C = 1,675 mA.g-1） after 100 cycles. A reversible capacity of 544 mAh.g-1 after 300 cycles was obtained even after increasing the current density to 0.5C, with a 0.039% capacity decay per cycle under a sulfur loading of 3.3 mg-cm-2. Moreover, a capacity of 466 mAh.g-1 after 100 cycles at 0.5C could still be obtained when the sulfur loading was increased to 6.96 mg.cm-2. The excellent electrochemical performance of the AZO@C/S composite can be attributed to its high conductivity of the polar AZO host, which suppresses the shuttle effect while simultaneously improving the redox kinetics in the reciprocal transformation of lithium sulfide species.

Transparency order versus confusion coefficient:a case study of NIST lightweight cryptography S-Boxes

Side-channel resistance is nowadays widely accepted as a crucial factor in deciding the security assurance level of cryptographic implementations.In most cases,non-linear components(e.g.S-Boxes)of cryptographic algorithms will be chosen as primary targets of side-channel attacks(SCAs).In order to measure side-channel resistance of S-Boxes,three theoretical metrics are proposed and they are revisited transparency order(VTO),confusion coefficients variance(CCV),and minimum confusion coefficient(MCC),respectively.However,the practical effectiveness of these metrics remains still unclear.Taking the 4-bit and 8-bit S-Boxes used in NIST Lightweight Cryptography candidates as concrete examples,this paper takes a comprehensive study of the applicability of these metrics.First of all,we empirically investigate the relations among three metrics for targeted S-boxes,and find that CCV is almost linearly correlated with VTO,while MCC is inconsistent with the other two.Furthermore,in order to verify which metric is more effective in which scenarios,we perform simulated and practical experiments on nine 4-bit S-Boxes under the non-profiled attacks and profiled attacks,respectively.The experiments show that for quantifying side-channel resistance of S-Boxes under non-profiled attacks,VTO and CCV are more reliable while MCC fails.We also obtain an interesting observation that none of these three metrics is suitable for measuring the resistance of S-Boxes against profiled SCAs.Finally,we try to verify whether these metrics can be applied to compare the resistance of S-Boxes with different sizes.Unfortunately,all of them are invalid in this scenario.

Transparency order versus confusion coefficient:a case study of NIST lightweight cryptography S‑Boxes

Side-channel resistance is nowadays widely accepted as a crucial factor in deciding the security assurance level of cryptographic implementations.In most cases,non-linear components(e.g.S-Boxes)of cryptographic algorithms will be chosen as primary targets of side-channel attacks(SCAs).In order to measure side-channel resistance of S-Boxes,three theoretical metrics are proposed and they are reVisited transparency order(VTO),confusion coefficients variance(CCV),and minimum confusion coefficient(MCC),respectively.However,the practical effectiveness of these metrics remains still unclear.Taking the 4-bit and 8-bit S-Boxes used in NIST Lightweight Cryptography candidates as concrete examples,this paper takes a comprehensive study of the applicability of these metrics.First of all,we empirically investigate the relations among three metrics for targeted S-boxes,and find that CCV is almost linearly correlated with VTO,while MCC is inconsistent with the other two.Furthermore,in order to verify which metric is more effective in which scenarios,we perform simulated and practical experiments on nine 4-bit S-Boxes under the nonprofiled attacks and profiled attacks,respectively.The experiments show that for quantifying side-channel resistance of S-Boxes under non-profiled attacks,VTO and CCV are more reliable while MCC fails.We also obtain an interesting observation that none of these three metrics is suitable for measuring the resistance of S-Boxes against profiled SCAs.Finally,we try to verify whether these metrics can be applied to compare the resistance of S-Boxes with different sizes.Unfortunately,all of them are invalid in this scenario.