Marc Davio

Analytical Characteristics of the DES.

The necessity to use cryptography in order to protect stored and transmitted data has been recognized in many commercial applications, such as electronic funds transfer (EFT), automated clearinghouses, etc ... (Diffie and Hellman, 1979).

Efficient hardware and software implementations for the DES

Importance of DES: NBS, ANSI and ISO (in study) have DES as standards.The available devices or programs have some tedious properties for an extensive use: ? hardware is expensive or slow, and limited, ? software is slow.We describe methods for obtaining efficient hardware and software implementations for the DES, i.e.

Dependence of output on input in DES: small avalanche characteristics

New general properties in the S-boxes were found. Techniques and theorems are presented which allow to evaluate the non-substitution effect in f and the key clustering in DES. Examples are given. Its importance related to the security of DES is discussed.

The importance of “good” key scheduling schemes (how to make a secure DES scheme with ≤48 bits keys?)

In DES the key scheduling scheme uses mainly shift registers. By modifying this key scheduling, conventional cryptosystems can be designed which are, e.g., strong against exhaustive key search attacks (without increasing the key size), or have public key like properties. Other effects obtainable by modifying the key scheduling and their importance are discussed.

Propagation characteristics of the DES

New general properties in the S-boxes were found. Techniques and theorems are presented which allow to evaluate the nonsubstitution effect in f and the key clustering in DES. Examples are given. Its importance related to the security of DES is discussed.

PHIPLA--A New Algorithm for Logic Minimization

PHIPLA, a new algorithm for logic minimization, is presented. The algorithm sets out to find optimal sum-of-products representations for a set of Boolean functions, thus contributing to area minimization of the Programmable Logic Array corresponding to the set of functions. The results of a comparative study of PHIPLA and two other algorithms, SPAM and PRESTOL-II, are presented. From these results it is concluded that PHIPLA generates representations which are competitive with those generated by SPAM and PRESTOL-II, whilst the algorithm is extremely fast for small problems (up to 12 variables).

PHIFACT-a design space exploration program

PHIFACT is a program to synthesize combinational blocks for performance. This is mainly achieved by design space exploration at logic level. The basic multi-level architecture of the block is gradually constructed during a Boolean phase, where look ahead tools guarantee optimality. During a subsequent local restructuring phase, optimal circuits scattered in subregions of the design space are explored and selected. This is mainly based on a steepest descent method in various directions. Consequently either the complete design space, or selected subregions can be examined. Both progresses are intimately connected, placing PHIFACT in the forefront of logic synthesis tools for performance.<<ETX>>

L’état de l’art en matière de techniques à clé publique

RésuméCantonné dans l’analyse de révolution des techniques à clé publique, cet article n’aborde pas du tout l’usage de ces techniques sur les réseaux de communication ou de diffusion. La carte à puce est la seule application partiellement abordée, non pas que la carte soit une application privilégiée, mais parce que la carte apporte une solution sécurisée et efficace à la mémorisation et à l’utilisation de paramètres secrets. Cet article est une rapide synthèse sur l’état de l’art dans le domaine des techniques à clé publique, ce vaste sujet où hasard et redondance jouent les premiers rôles, principalement dans les techniques d’intégrité: identification, authentication, signature.AbstractRestricted to an analysis of technical evolutions, this document does not deal with the use of public keys in communication and broadcasting networks. Smart card is the only application which is partially dealt with, not because it should be an exceptional application, but rather because smart cards are very efficient and very secure for both storing and using secret parameters. This document is a brief synthesis of this large subject where randomness and redundancy play the major roles, mainly in integrity techniques: identification, authentication and signature.