Chaotic Cryptography in Digital World: State-of-the-Art, Problems and Solutions

Since 1989, many contributions have been devoted to the methods of using chaos to construct digital ciphers. Although some chaotic ciphers have been known insecure and several defects have been found, a large number of chaotic ciphers still remain secure till now. Furthermore, in the past few years, some novel chaotic ciphers have been proposed, which avoid some weaknesses in previous chaotic ciphers and seem to have stronger cryptographic properties. In this paper, we first review the progress of the digital chaotic ciphers nowadays from 1989 till now (2002), and then discuss some problems in the general design of digital chaotic ciphers and possible solutions

Improving Security of a Chaotic Encryption Approach

E. Alvarez et al. presented a new chaotic encryption approach recently. But soon G. Alvarez et al. broke it with four cryptanalytic methods and found some other weaknesses. In this letter we point out why the original scheme is so vulnerable to the proposed four attacks. The chief reasons are two essential defects existing in the original scheme. Based on such a fact, we present an improved encryption scheme to obtain higher security. The cryptographic properties of the improved scheme are studied theoretically and experimentally in detail

Confning TiO2 Nanotubes in PECVD‑Enabled Graphene Capsules Toward Ultrafast K‑Ion Storage: In Situ TEM/XRD Study and DFT Analysis

© 2020, © 2020, The Author(s). Titanium dioxide (TiO2) has gained burgeoning attention for potassium-ion storage because of its large theoretical capacity, wide availability, and environmental benignity. Nevertheless, the inherently poor conductivity gives rise to its sluggish reaction kinetics and inferior rate capability. Here, we report the direct graphene growth over TiO2 nanotubes by virtue of chemical vapor deposition. Such conformal graphene coatings effectively enhance the conductive environment and well accommodate the volume change of TiO2 upon potassiation/depotassiation. When paired with an activated carbon cathode, the graphene-armored TiO2 nanotubes allow the potassium-ion hybrid capacitor full cells to harvest an energy/power density of 81.2 Wh kg−1/3746.6 W kg−1. We further employ in situ transmission electron microscopy and operando X-ray diffraction to probe the potassium-ion storage behavior. This work offers a viable and versatile solution to the anode design and in situ probing of potassium storage technologies that is readily promising for practical applications.[Figure not available: see fulltext.]

Performance analysis of Jakimoski-Kocarev attack on a class of chaotic cryptosystems

Recently G. Jakimoski and L. Kocarev cryptanalzed two chaotic cryptosystems without using chaotic synchronization -- Baptista cryptosystem and Alvarez cryptosystem. As a result, they pointed out that neither of the two cryptosystems are secure to known-plaintext attacks. In this letter, we re-study the performance of Jakimoski-Kocarev attack on Baptista cryptosystem and find that it is not e#cient enough as a practical attack tool. Furthermore, a simple but e#ective remedy is presented to resist Jakimoski-Kocarev attack, and the detailed discussion on its performance are given

On the Security of a Chaotic Encryption Scheme: Problems With Computerized Chaos in Finite Computing Precision

H. Zhou et al. have proposed a chaotic encryption scheme, which is based on a kind of computerized piecewise linear chaotic map (PWLCM) realized in finite computing precision. In this paper, we point out that Zhou's encryption scheme is not secure enough from strict cryptographic viewpoint. The reason lies in the dynamical degradation of the computerized piecewise linear chaotic map employed by H. Zhou et al. The dynamical degradation of the computerized chaos induces many weak keys to cause large information leaking of the plaintext. In addition, we also discuss three simple countermeasures to enhance the security of Zhou's cryptosystem, but none of them can essentially enhance the security