RESUMEN
Embedded encryption devices and smart sensors are vulnerable to physical attacks. Due to the continuous shrinking of chip size, laser injection, particle radiation and electromagnetic transient injection are possible methods that introduce transient multiple faults. In the fault analysis stage, the adversary is unclear about the actual number of faults injected. Typically, the single-nibble fault analysis encounters difficulties. Therefore, in this paper, we propose novel ciphertext-only impossible differentials that can analyze the number of random faults to six nibbles. We use the impossible differentials to exclude the secret key that definitely does not exist, and then gradually obtain the unique secret key through inverse difference equations. Using software simulation, we conducted 32,000 random multiple fault attacks on Midori. The experiments were carried out to verify the theoretical model of multiple fault attacks. We obtain the relationship between fault injection and information content. To reduce the number of fault attacks, we further optimized the fault attack method. The secret key can be obtained at least 11 times. The proposed ciphertext-only impossible differential analysis provides an effective method for random multiple faults analysis, which would be helpful for improving the security of block ciphers.
RESUMEN
In this study, electromagnetically induced transparency (EIT) effect in all-dielectric metamaterial for dual-band linear-to-circular (LTC) polarization conversion is demonstrated numerically and experimentally. The unit cell is composed of three ceramic blocks with different sizes. Due to the anisotropy of metamaterial and polarization dependence of subsequent EIT effects, transmission spectra for x- and y-polarized incident waves are realized to induce LTC polarization conversion. It is numerically demonstrated that a linearly polarized incident wave is transformed to a nearly perfect circularly polarized wave at around 6.24 and 6.38 GHz. The corresponding ellipticity and transmittivity are about 0.96, 0.6 and 0.94, 0.37, respectively. A metamaterial sample is fabricated and its transmission spectra are measured. The measured results are nearly equal to the simulated results. This LTC polarization convertor, with low loss and ultra thinness, may expand the application of EIT metamaterials, and it can be extended to terahertz up to optical bands. Such a design may find potential applications in microwave wave plates and metamaterial antennas, or other electromagnetic control devices.