L. Encinas - Academia.edu (original) (raw)

Papers by L. Encinas

Research paper thumbnail of Graphic Cryptography with Pseudorandom Bit Generators and Cellular Automata

Lecture Notes in Computer Science, 2003

In this paper we propose a new graphic symmetrical cryptosystem in order to encrypt a colored ima... more In this paper we propose a new graphic symmetrical cryptosystem in order to encrypt a colored image defined by pixels and by any number of colors. This cryptosystem is based on a reversible bidimensional cellular automaton and uses a pseudorandom bit generator. As the key of the cryptosystem is the seed of the pseudorandom bit generator, the latter has to be cryptographically secure. Moreover, the recovered image from the ciphered image has not loss of resolution and the ratio between the ciphered image and the original one, i.e., the factor expansion of the cryptosystem, is 1.

Research paper thumbnail of Security Efficiency Analysis of a Biometric Fuzzy Extractor for Iris Templates

Advances in Intelligent and Soft Computing, 2009

A Biometric fuzzy extractor scheme for iris templates was recently presented in [3]. This fuzzy e... more A Biometric fuzzy extractor scheme for iris templates was recently presented in [3]. This fuzzy extractor binds a cryptographic key with the iris template of a user, allowing to recover such cryptographic key by authenticating the user by means of a new iris template from her. In this work, an analysis of the security efficiency of this fuzzy extractor is carried out by means of a study about the behavior of the scheme with cryptographic keys of different bitlengths: 64, 128, 192, and 256. The different sizes of the keys permit to analyze the variability of the intra-and inter-user in the iris templates.

Research paper thumbnail of Cryptography: optional subject in the degree in computer engineering in information technologies

European Journal of Science and Mathematics Education

Cryptography subject is part of the curriculum of the Bachelor's Degree in Computer Engineering i... more Cryptography subject is part of the curriculum of the Bachelor's Degree in Computer Engineering in Information Systems, at the University of Salamanca. This subject becomes easy to understand if the history of Cryptography is used. The basic mathematics includes the following main topics: Modular arithmetic, algebraic curves, finite fields and number theory. Cryptography is a means of protecting personal information to avoid an eavesdropper can access it. From the first century AD with the Julius Caesar cipher to the present day with RSA, ElGamal, knapsack or elliptic curve cryptosystems, the Cryptography has evolved. In this paper we will show the syllabus of Cryptography subject and how the history knowledge supposes an important part of it, and helps students to acquire the skills and competences included in the subject curriculum.

Research paper thumbnail of Study of the stability of a SEIRS model for computer worm propagation

Physica A: Statistical Mechanics and its Applications

Research paper thumbnail of Hidden and Nonstandard Bifurcation Diagram of an Alternate Quadratic System

International Journal of Bifurcation and Chaos, 2016

Alternate quadratic systems [Formula: see text] where [Formula: see text] and [Formula: see text]... more Alternate quadratic systems [Formula: see text] where [Formula: see text] and [Formula: see text] are different parameters, seem to be interval maps in a range of the parameter values. However, after a careful graphical analysis of their bifurcation diagrams we conclude that this is true only for system B, but not for system A. In system A we find a hidden and nonstandard bifurcation diagram (“hidden” because it is not visible at normal resolution and “nonstandard” because the bifurcation diagram is empty for some ranges of the parameter values). The different behavior of the underlying critical polynomial in the range of parameter values in both alternate quadratic systems explains why the hidden and nonstandard bifurcation diagram is present in system A and not in system B. The analysis of the Lyapunov exponent also shows both the existence and the different behavior of the hidden bifurcation diagram of system A.

Research paper thumbnail of Extreme Preservers of Maximal Column Rank Inequalities of Matrix Multiplications Over Semirings

Journal of the Korean Mathematical Society, 2010

We characterize linear operators that preserve sets of matrix ordered pairs which satisfy extreme... more We characterize linear operators that preserve sets of matrix ordered pairs which satisfy extreme cases with respect to maximal column rank inequalities of matrix multiplications over semirings.

Research paper thumbnail of Nuevos parámetros seguros para el criptosistema de Chor-Rivest e implementación con Magma

Research paper thumbnail of A Group Signature Scheme Based on the Integer Factorization and the Subgroup Discrete Logarithm Problems

Lecture Notes in Computer Science, 2011

Group signature schemes allow a user, belonging to a specific group of users, to sign a message i... more Group signature schemes allow a user, belonging to a specific group of users, to sign a message in an anonymous way on behalf of the group. In general, these schemes need the collaboration of a Trusted Third Party which, in case of a dispute, can reveal the identity of the real signer. A new group signature scheme is presented whose security is based on the Integer Factorization Problem (IFP) and on the Subgroup Discrete Logarithm Problem (SDLP).

Research paper thumbnail of A Multisignature Scheme Based on the SDLP and on the IFP

Lecture Notes in Computer Science, 2011

Multisignature schemes are digital signature schemes that permit one to determine a unique signat... more Multisignature schemes are digital signature schemes that permit one to determine a unique signature for a given message, depending on the signatures of all the members of a specific group. In this work, we present a new semi-short multisignature scheme based on the Subgroup Discrete Logarithm Problem (SDLP) and on the Integer Factorization Problem (IFP). The scheme can be carried out in an on-and off-line basis, is efficient, and the bitlength of the multisignature does not depend on the number of signers.

Research paper thumbnail of Elliptic curve cryptography. Java platform implementations

ABSTRACT Elliptic Curve Cryptography (ECC) is one of the most interesting systems for protecting ... more ABSTRACT Elliptic Curve Cryptography (ECC) is one of the most interesting systems for protecting sensitive information nowadays. The latest versions of the Java Platform include classes and interfaces making ECC available to programmers, but due to the nature of Java it is still necessary to employ additional third party packages in order to use cryptographic operations and procedures related to ECC. In the present work, an extensive review of the most important ECC implementations in Java is presented.

Research paper thumbnail of Fractal sets attached to homogeneous quadratic maps in two variables

Physica D: Nonlinear Phenomena, 2013

ABSTRACT The fractal set attached to the iteration of a “generic” homogeneous quadratic map from ... more ABSTRACT The fractal set attached to the iteration of a “generic” homogeneous quadratic map from the plane to itself is studied and depicted, by using a two-parametric family of normal forms obtained from the theory of invariants of symmetric bilinear maps F:R×R→RF:R×R→R under the full linear group of the plane. While invariant theory classifies maps F:C×C→CF:C×C→C on the complex plane, we confine ourselves to consider maps on the real plane, in order to include the results obtained from the theory of two-dimensional discrete dynamical systems. A discrete number of “topological types” for such fractals is conjectured to exist.

Research paper thumbnail of Developing ECC applications in Java Card

2013 9th International Conference on Information Assurance and Security (IAS), 2013

Research paper thumbnail of Non-degenerate bilinear alternating maps f : V × V → V, dim(V) = 3, over an algebraically closed field

Let V be a three-dimensional vector space over an algebraically closed field F. Non-degenerate el... more Let V be a three-dimensional vector space over an algebraically closed field F. Non-degenerate elements in 2 V * ⊗ V under the tensorial action of the linear group GL(V), are classified.

Research paper thumbnail of Elliptic curve cryptography: Java implementation issues

Proceedings 39th Annual 2005 International Carnahan Conference on Security Technology, 2005

... security package. 5. JAVA IMPLEMENTATIONS There are several libraries and criptographic modul... more ... security package. 5. JAVA IMPLEMENTATIONS There are several libraries and criptographic modules in the marketthat can be used for the development of security pro-grams. The most important are: * Botan (http://botan.randombit.net/intro.html) ...

Research paper thumbnail of Modelling of Forest Fire Spreading by Using Hexagonal Cellular Automata

Proceedings of the Fifth International Conference on Engineering Computational Technology, 2006

Research paper thumbnail of Comment on ‘A technique for image encryption using digital signature’

Optics Communications, 2006

The security of a recently proposed technique for encryption images by Sinha and Singh [A. Sinha,... more The security of a recently proposed technique for encryption images by Sinha and Singh [A. Sinha, K. Singh, Opt. Commun. 218 (2003) 229], based on the use of digital signatures and error correcting codes, is analyzed. The proposed cryptosystem is shown to have some weakness. In fact, the secret key and the original image can be recovered efficiently by a brute force attack.

Research paper thumbnail of Symplectic structure and gauge invariance on the cotangent bundle

Journal of Mathematical Physics, 1994

The cotangent bundle of a manifold M can be identified with the bundle of connections of the triv... more The cotangent bundle of a manifold M can be identified with the bundle of connections of the trivial bundle M×U(1). Hence, there exists a natural representation of the U(1)-invariant vector fields on M×U(1) extending the gauge representation into the Lie algebra of vector fields on T*(M). It is proved herein that a differential form on T*(M) is invariant under this representation (resp. gauge invariant) if and only if it belongs to the R-algebra [resp. to the Ω ˙ (M)-algebra] generated by the canonical symplectic form of the cotangent bundle.

Research paper thumbnail of Partitioning large data sets: Use of statistical methods applied to a set of Russian igneous-rock chemical analyses

Computers & Geosciences, 1994

Research paper thumbnail of A secure scheme to share secret color images

Computer Physics Communications, 2005

The main goal of this work is to study how discrete dynamical systems can be used to design secre... more 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.

Research paper thumbnail of Diseño de un nuevo generador de secuencias de bits aleatorios por entrada de teclado

novática, 2005

... El valor estadístico estudiado es: que sigue una distribución Chi cuadrado con 2m – 1 grados ... more ... El valor estadístico estudiado es: que sigue una distribución Chi cuadrado con 2m – 1 grados de libertad (l = 2m – 1). 4. Test de Rachas. ... Si la racha está formada por ceros se conoce como hueco mientras que si está formada por unos se denomina bloque. ...

Research paper thumbnail of Graphic Cryptography with Pseudorandom Bit Generators and Cellular Automata

Lecture Notes in Computer Science, 2003

In this paper we propose a new graphic symmetrical cryptosystem in order to encrypt a colored ima... more In this paper we propose a new graphic symmetrical cryptosystem in order to encrypt a colored image defined by pixels and by any number of colors. This cryptosystem is based on a reversible bidimensional cellular automaton and uses a pseudorandom bit generator. As the key of the cryptosystem is the seed of the pseudorandom bit generator, the latter has to be cryptographically secure. Moreover, the recovered image from the ciphered image has not loss of resolution and the ratio between the ciphered image and the original one, i.e., the factor expansion of the cryptosystem, is 1.

Research paper thumbnail of Security Efficiency Analysis of a Biometric Fuzzy Extractor for Iris Templates

Advances in Intelligent and Soft Computing, 2009

A Biometric fuzzy extractor scheme for iris templates was recently presented in [3]. This fuzzy e... more A Biometric fuzzy extractor scheme for iris templates was recently presented in [3]. This fuzzy extractor binds a cryptographic key with the iris template of a user, allowing to recover such cryptographic key by authenticating the user by means of a new iris template from her. In this work, an analysis of the security efficiency of this fuzzy extractor is carried out by means of a study about the behavior of the scheme with cryptographic keys of different bitlengths: 64, 128, 192, and 256. The different sizes of the keys permit to analyze the variability of the intra-and inter-user in the iris templates.

Research paper thumbnail of Cryptography: optional subject in the degree in computer engineering in information technologies

European Journal of Science and Mathematics Education

Cryptography subject is part of the curriculum of the Bachelor's Degree in Computer Engineering i... more Cryptography subject is part of the curriculum of the Bachelor's Degree in Computer Engineering in Information Systems, at the University of Salamanca. This subject becomes easy to understand if the history of Cryptography is used. The basic mathematics includes the following main topics: Modular arithmetic, algebraic curves, finite fields and number theory. Cryptography is a means of protecting personal information to avoid an eavesdropper can access it. From the first century AD with the Julius Caesar cipher to the present day with RSA, ElGamal, knapsack or elliptic curve cryptosystems, the Cryptography has evolved. In this paper we will show the syllabus of Cryptography subject and how the history knowledge supposes an important part of it, and helps students to acquire the skills and competences included in the subject curriculum.

Research paper thumbnail of Study of the stability of a SEIRS model for computer worm propagation

Physica A: Statistical Mechanics and its Applications

Research paper thumbnail of Hidden and Nonstandard Bifurcation Diagram of an Alternate Quadratic System

International Journal of Bifurcation and Chaos, 2016

Alternate quadratic systems [Formula: see text] where [Formula: see text] and [Formula: see text]... more Alternate quadratic systems [Formula: see text] where [Formula: see text] and [Formula: see text] are different parameters, seem to be interval maps in a range of the parameter values. However, after a careful graphical analysis of their bifurcation diagrams we conclude that this is true only for system B, but not for system A. In system A we find a hidden and nonstandard bifurcation diagram (“hidden” because it is not visible at normal resolution and “nonstandard” because the bifurcation diagram is empty for some ranges of the parameter values). The different behavior of the underlying critical polynomial in the range of parameter values in both alternate quadratic systems explains why the hidden and nonstandard bifurcation diagram is present in system A and not in system B. The analysis of the Lyapunov exponent also shows both the existence and the different behavior of the hidden bifurcation diagram of system A.

Research paper thumbnail of Extreme Preservers of Maximal Column Rank Inequalities of Matrix Multiplications Over Semirings

Journal of the Korean Mathematical Society, 2010

We characterize linear operators that preserve sets of matrix ordered pairs which satisfy extreme... more We characterize linear operators that preserve sets of matrix ordered pairs which satisfy extreme cases with respect to maximal column rank inequalities of matrix multiplications over semirings.

Research paper thumbnail of Nuevos parámetros seguros para el criptosistema de Chor-Rivest e implementación con Magma

Research paper thumbnail of A Group Signature Scheme Based on the Integer Factorization and the Subgroup Discrete Logarithm Problems

Lecture Notes in Computer Science, 2011

Group signature schemes allow a user, belonging to a specific group of users, to sign a message i... more Group signature schemes allow a user, belonging to a specific group of users, to sign a message in an anonymous way on behalf of the group. In general, these schemes need the collaboration of a Trusted Third Party which, in case of a dispute, can reveal the identity of the real signer. A new group signature scheme is presented whose security is based on the Integer Factorization Problem (IFP) and on the Subgroup Discrete Logarithm Problem (SDLP).

Research paper thumbnail of A Multisignature Scheme Based on the SDLP and on the IFP

Lecture Notes in Computer Science, 2011

Multisignature schemes are digital signature schemes that permit one to determine a unique signat... more Multisignature schemes are digital signature schemes that permit one to determine a unique signature for a given message, depending on the signatures of all the members of a specific group. In this work, we present a new semi-short multisignature scheme based on the Subgroup Discrete Logarithm Problem (SDLP) and on the Integer Factorization Problem (IFP). The scheme can be carried out in an on-and off-line basis, is efficient, and the bitlength of the multisignature does not depend on the number of signers.

Research paper thumbnail of Elliptic curve cryptography. Java platform implementations

ABSTRACT Elliptic Curve Cryptography (ECC) is one of the most interesting systems for protecting ... more ABSTRACT Elliptic Curve Cryptography (ECC) is one of the most interesting systems for protecting sensitive information nowadays. The latest versions of the Java Platform include classes and interfaces making ECC available to programmers, but due to the nature of Java it is still necessary to employ additional third party packages in order to use cryptographic operations and procedures related to ECC. In the present work, an extensive review of the most important ECC implementations in Java is presented.

Research paper thumbnail of Fractal sets attached to homogeneous quadratic maps in two variables

Physica D: Nonlinear Phenomena, 2013

ABSTRACT The fractal set attached to the iteration of a “generic” homogeneous quadratic map from ... more ABSTRACT The fractal set attached to the iteration of a “generic” homogeneous quadratic map from the plane to itself is studied and depicted, by using a two-parametric family of normal forms obtained from the theory of invariants of symmetric bilinear maps F:R×R→RF:R×R→R under the full linear group of the plane. While invariant theory classifies maps F:C×C→CF:C×C→C on the complex plane, we confine ourselves to consider maps on the real plane, in order to include the results obtained from the theory of two-dimensional discrete dynamical systems. A discrete number of “topological types” for such fractals is conjectured to exist.

Research paper thumbnail of Developing ECC applications in Java Card

2013 9th International Conference on Information Assurance and Security (IAS), 2013

Research paper thumbnail of Non-degenerate bilinear alternating maps f : V × V → V, dim(V) = 3, over an algebraically closed field

Let V be a three-dimensional vector space over an algebraically closed field F. Non-degenerate el... more Let V be a three-dimensional vector space over an algebraically closed field F. Non-degenerate elements in 2 V * ⊗ V under the tensorial action of the linear group GL(V), are classified.

Research paper thumbnail of Elliptic curve cryptography: Java implementation issues

Proceedings 39th Annual 2005 International Carnahan Conference on Security Technology, 2005

... security package. 5. JAVA IMPLEMENTATIONS There are several libraries and criptographic modul... more ... security package. 5. JAVA IMPLEMENTATIONS There are several libraries and criptographic modules in the marketthat can be used for the development of security pro-grams. The most important are: * Botan (http://botan.randombit.net/intro.html) ...

Research paper thumbnail of Modelling of Forest Fire Spreading by Using Hexagonal Cellular Automata

Proceedings of the Fifth International Conference on Engineering Computational Technology, 2006

Research paper thumbnail of Comment on ‘A technique for image encryption using digital signature’

Optics Communications, 2006

The security of a recently proposed technique for encryption images by Sinha and Singh [A. Sinha,... more The security of a recently proposed technique for encryption images by Sinha and Singh [A. Sinha, K. Singh, Opt. Commun. 218 (2003) 229], based on the use of digital signatures and error correcting codes, is analyzed. The proposed cryptosystem is shown to have some weakness. In fact, the secret key and the original image can be recovered efficiently by a brute force attack.

Research paper thumbnail of Symplectic structure and gauge invariance on the cotangent bundle

Journal of Mathematical Physics, 1994

The cotangent bundle of a manifold M can be identified with the bundle of connections of the triv... more The cotangent bundle of a manifold M can be identified with the bundle of connections of the trivial bundle M×U(1). Hence, there exists a natural representation of the U(1)-invariant vector fields on M×U(1) extending the gauge representation into the Lie algebra of vector fields on T*(M). It is proved herein that a differential form on T*(M) is invariant under this representation (resp. gauge invariant) if and only if it belongs to the R-algebra [resp. to the Ω ˙ (M)-algebra] generated by the canonical symplectic form of the cotangent bundle.

Research paper thumbnail of Partitioning large data sets: Use of statistical methods applied to a set of Russian igneous-rock chemical analyses

Computers & Geosciences, 1994

Research paper thumbnail of A secure scheme to share secret color images

Computer Physics Communications, 2005

The main goal of this work is to study how discrete dynamical systems can be used to design secre... more 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.

Research paper thumbnail of Diseño de un nuevo generador de secuencias de bits aleatorios por entrada de teclado

novática, 2005

... El valor estadístico estudiado es: que sigue una distribución Chi cuadrado con 2m – 1 grados ... more ... El valor estadístico estudiado es: que sigue una distribución Chi cuadrado con 2m – 1 grados de libertad (l = 2m – 1). 4. Test de Rachas. ... Si la racha está formada por ceros se conoce como hueco mientras que si está formada por unos se denomina bloque. ...