L. Hernández Encinas

Simulation of forest fire fronts using cellular automata

In this work a new model for fire front spreading based on two-dimensional cellular automata is proposed. It is a more realistic modification of the model introduced by Karafyllidis and Thanailakis (see [Karafyllidis I, Thanailakis A. A model for predicting forest fire spreading using cellular automata. Ecol Model 1997;99:87-97]), which is based on the transfer of fractional burned area. Specifically, the model proposed in this work introduces a more accurate factor of propagation from a diagonal neighbor cell and includes, in a detailed form, the rate of fire spread. Moreover, the model is useful for both homogeneous and inhomogeneous environments. Some tests have been passed in order to determine the goodness of the method.

A multisecret sharing scheme for color images based on cellular automata

In this work a new multisecret sharing scheme for secret color images among a set of users is proposed. The protocol allows that each participant in the scheme to share a secret color image with the rest of participants in such a way that all of them can recover all the secret color images only if the whole set of participants pools their shadows. The proposed scheme is based on the use of bidimensional reversible cellular automata with memory. The security of the scheme is studied and it is proved that the protocol is ideal and perfect and that it resists the most important statistical attacks.

A crypto-biometric scheme based on iris-templates with fuzzy extractors

One of the most important uses of Biometrics is the identification and authentication of individuals using one or several of their physiognomical or behavioral features. Moreover, Biometrics offers a good option to assist Cryptography for confidentiality, encryption, and decryption of messages by using some biometric traits. In this paper, a crypto-biometric scheme, based on fuzzy extractors, by using iris templates, is proposed, i.e., we propose a new system in order to permit a user to retrieve a secret or a previously saved key by using her own biometric template. The properties and efficiency for selecting the most useful parameters to provide a high level of security in the scheme are thoroughly analyzed.

Inverse rules of ECA with rule number 150

The explicit expressions of local transition functions of the inverse cellular automata of elementary cellular automata with rule number 150 and periodic boundary conditions are given. The procedure to obtain such local transition functions is based on the algebraic properties of elementary cellular automata.

Isomorphism Classes of Genus-2 Hyperelliptic Curves Over Finite Fields

Abstract. We propose a reduced equation for hyperelliptic curves of genus 2 over finite fields ?q of q elements with characteristic different from 2 and 5. We determine the number of isomorphism classes of genus-2 hyperelliptic curves having an ?q-rational Weierstrass point. These results have applications to hyperelliptic curve cryptography.

A secure scheme to share secret color images

The main goal of this work is to study how discrete dynamical systems can be used to design secret sharing schemes. Specifically, the proposed scheme permits to share secret color images, and it is based on bidimensional cellular automata. The main idea is to analyze how a simple reversible model of computation allows one to compute the shares and then using the reverse computation in order to recover the secret image. Moreover, the proposed scheme exhibits good statistical properties.

A short proof of the generalized Faà di bruno's formula☆

A short proof of the generalized Faa di Bruno formula is given and an explicit parametrization of the set of indices involved in the coefficient of a specific term of the formula is provided. An application is also included.

Faá di Bruno's formula, lattices, and partitions

The coefficients of g(s) in expanding the rth derivative of the composite function g ○ f by Faa di Brunos formula, is determined by a Diophantine linear system, which is proved to be equivalent to the problem of enumerating partitions of a finite set of integers attached to r and s canonically.

Elliptic curve cryptography: Java implementation issues

Elliptic curve cryptography (ECC) is based in one of the hardest arithmetic problems, the elliptic curve discrete logarithm problem, making ECC a reliable cryptographic technique. In addition to this advantage, ECC requires shorter keys compared to other public key algorithms, which suggests its use in low-end systems such as smart cards because of its efficiency and limited hardware requirements. Currently the leading smart card technology is Java card. Though both Java 2 standard edition (J2SE) 5.0 and Java card (JC) 2.2.1 include classes and interfaces making ECC available to Java programs, they are not complete, making it necessary to use additional, non-standard packages if the programmer wants to use ECC for different operations (digital signature, data encryption and decryption, etc.). In the present work, we provide a complete review of the state of the art of ECC in J2SE and Java card, with a complete list of operations available in both standard implementations and proprietary packages.

A comparison of the standardized versions of ECIES

Elliptic Curve Cryptography (ECC) can be used as a tool for encrypting data, creating digital signatures or performing key exchanges. In relation to encryption, the Elliptic Curve Integrated Encryption Scheme (ECIES) is the best known scheme based on ECC, and as such it has been included in several cryptographic standards. In the present work, we provide an extensive review and comparison of the versions of ECIES included in documents from ANSI, IEEE, ISO/IEC, and SECG, highlighting the main differences between them that can prevent implementations of ECIES from being fully interoperable.