Bull Cp8

Cp8 Technologies

Nds Corporation

Cp8 Transac

Jacques Patarin

Louis Goubin

Aviad Kipnis

Michel Ugon

The invention provides for a cryptographic method for digital signature. A set Sof k polynomial functions P(x, . . . , x, y, . . . , y) are supplied as a public key, where k, v, and n are integers, x, . . . , xare n+v variables of a first type, and y, . . . , yare k variables of a second type, the set Sbeing obtained by applying a secret key operation on a given set Sof k polynomial functions P'(a, . . . , a, y, . . . , y), a, . . . , adesignating n+v variables including a set of n 'oil' and v 'vinegar' variables. A message to be signed is provided and submitted to a hash function to produce a series of k values b, . . . , b. These k values are substituted for the k variables y, . . . . , yof the set Sto produce a set Sof k polynomial functions P&#x2033;(a, . . . , a), and v values a&#x2032;, . . . , a&#x2032;, are selected for the v &#x201c;vinegar&#x201d; variables. A set of equations P&#x2033;(a, . . . , a&#x2032;)=0 is solved to obtain a solution for a&#x2032;, . . . , a&#x2032;and the secret key operation is applied to transform the solution to the digital signature.

Public-key signature methods and systems

The invention relates to a method for protecting one or more computer systems using the same secret key (Ks) cryptographic algorithm, characterized in that the way in which said calculation is performed depends, for each computer system and for each secret key, on secret data (Ds) stored in a secret area of the computer system or systems.

Method for making secure one or several computer installations using a common secret key algorithm, use of the method and a computer system utilizing the method

Secret key cryptographic process for protecting a computer system against attacks by physical analysis

Asymmetrical cryptographic communication method and portable object

A method and an apparatus for authenticating a data carrier enables a transaction or access to a service or a location, and the corresponding carrier. The carrier (1) has a specific number (Ns) and an authentication value calculated from the specific number and from information (I) that defines the rights attaching to the carrier by means of an asymmetrical algorithm (F) and a secret key (Ks). Two types of authentication are provided. One is current, in a mode disconnected from the authorizing organization. The other is periodic, in a connected mode. In the disconnected mode, an algorithm (G) correlated with the asymmetrical algorithm (F) and using a public key (Kp) is applied to the authentication value (VA), read from the carrier, in order to verify that the authentication value (VA) is compatible with the specific number (Ns) and the information (I), and that the transaction or service requested is compatible with the information (I). In the connected mode, it is also possible to modify the authentication value of the carrier.

Method and apparatus for authenticating a data carrier intended to

Process for entry of a confidential piece of information and associated

A novel asymmetrical cryptographic schema which can be used for enciphering, signature and authentication. The schema is based on low degree public polynomial equations with value in a finite ring K. The mechanism is not necessarily bijective. The secret key makes it possible to hide polynomial equations with value in extensions of the ring K. The solving of these equations makes it possible, if one has the secret key, to execute operations which are not executable with the public key alone.

Cryptographic communication process

A process for authentication by an offline terminal (1) of a portable object (2) including a processing circuit (4) able to deliver a secondary value (Rx) which the function of a primary value (Qi) transmitted by the terminal. An authentication table (5) is placed in the terminal which associates a series of primary values (Qi) and a series of control values (Ui), each control value being the transformation by a oneway function of the secondary value (Rx) calculated by the processing circuit of an authentic portable object. At the time of a connection of a portable object with the terminal, one of the primary values (Qi) from the table is transmitted to the portable object, the one-way function is applied to the secondary value (Rx) received from the portable object, and the result obtained is compared with the corresponding control value (Ui) from the table.

Growing community of inventors

Viroflay, France

Jacques Patarin