Higher Order Differential Attack against Full-Round BIG

BIG is a 128-bit block cipher proposed by Demeri et al. in 2019. The number of rounds is 18 for high security. The designer evaluated its security against linear cryptanalysis. On the other hand, it has not been reported the security of BIG against higher order differential attack, which is one of the algebraic attacks. In this paper, we focused on a higher order differential of BIG. We found a new 15-round saturation characteristc of BIG using 1-st order differential by computer experiment. Exploiting this characteristic, we show that full-round BIG can be attacked with 6 chosen plaintexts and 2^(2.7) encryption operations

Security Enhancement of Various MPKCs by 2-layer Nonlinear Piece In Hand Method

Following the last proposal of the nonlinear Piece in Hand method, which has 3-layer structure, 2-layer nonlinear Piece in Hand method is proposed. Both of them aim at enhancing the security of existing and future multivariate public key cryptosystems. The new nonlinear Piece in Hand is compared with the 3-layer method and PMI+, which was proposed by Ding, et al

Local structure of alkalis in mixed-alkali borate glass to elucidate the origin of mixed-alkali effect

We report the structural analysis of Na+ and Cs+ in sodium cesium borate crystals and glasses using 23Na and 133Cs magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The composition dependence of NMR spectra of the borate was similar to that of the silicate: (1) the peak position of cesium borate crystals shifted to upfield for structures with larger Cs+ coordination numbers, (2) the MAS NMR spectra of xNa2O-yCs2O-3B2O3 (x = 0, 0.25, 0.5, 0.75, 1.0, x + y = 1) glass showed that the average coordination number (CN) of both the alkali cations decreases with increasing Cs+/(Na+ + Cs+) ratio. However, the degree of decrement in borates is much smaller than that in silicates. We have considered that the small difference in CN is due to 4-coordinated B, because it is electrically compensated by the alkali metal ions resulting in the restriction of having various coordinations of O to alkali metal