Thales

Eric Garrido

François Delaveau

Sandrine Agagliate

Philippe Painchault

Sandra Marcello

Thibault De Moegen

Renaud Dubois

Jean Martinelli

Florent Bernard

Alain Sauzet

David Lefranc

Thomas Prest

Valentin Mascre

Olivier Bernard

Alexandre Anzala Yamajako

Anne-Rose Gratadour

Christiane Kameni

Sonia Belaid

Antoine Christin

Lucile Quatravaux

Aurélien Dupin

A method and system for testing the cryptographic integrity of data m comprises at least the following elements: a module transmitting a message M, said module comprising a memory for storing the parameters used to execute the steps of the method, such as the key, the public data, a transmission medium, a receiver module also comprising storage means for storing at least the same parameters as in transmission. The system may comprise storage means for storing confidential data such as the secret keys, a processor suitable for executing the steps.

Method and system making it possible to test a cryptographic integrity of an error tolerant data item

A method of transmitting information between a plurality of radioelectric stations and an associated transmission network are disclosed. In one aspect, the method transmits information between radioelectric stations, each station including a transmitter and a receiver, the information including NbMot words of data, NbMot being an integer &#x3e;1. The transmission method includes: determining at least one polynomial of degree NbMot&#x2212;1, each of the NbMot coefficients of the polynomial corresponding to a respective word, the polynomial having an indeterminacy, calculating NbRepet polynomial values for the polynomial, NbRepet being an integer &#x3e;1, each polynomial value being calculated for a respective predetermined value of the indeterminacy, transmitting the calculated polynomial values from one radioelectric station to at least one other radioelectric station, receiving polynomial values by the other radioelectric station, and determining, via the other radioelectric station, the NbMot words from a Lagrange interpolation of the received polynomial values.

Method of transmitting information between a plurality of radioelectric stations and associated transmission network

The invention relates to a method for broadcasting data in a system using a BES (A) stateless scheme using a binary tree T with a KEKs No 2 key structure, i.e. such that a key kis associated with each difference of subsets S, and a root key kassociated with the set of the tree T and a BES (A) 'stateful' scheme using the same binary tree T with a KEKs No 1 key structure, i.e. such that a key kis associated with each subtree Swherein the scheme (A) is used for the current broadcast session and the keys known by the denied users are updated with a 'stateful' scheme (A) from time to time.

Hybrid method for distributing keys for the diffusion of encrypted data

A method for managing keys making it possible for a user to access one or more given services S in a communication system, in which the user is not able to be continuously connected to this service. A key K(t) is generated, which provides access to the service of day [t] for all the t&#x3c;tby using a one-way function in the following manner (a one-way function being defined as being a function for which it is not currently possible by computing means to obtain the inverse function). A root key K(t) is used and the key K(t) is generated for the day [t] prior to the day t, by using a function f such that K(t&#x2212;1)=f(K(t)). The new value of key K(t) is used in order to generate the key for the previous day K(t) and this step is reiterated over the limited time period of day [t] to day [t+d] in order to obtain the chain K(t+d&#x2212;1), K(t+d&#x2212;2), etc. Each day t the key K(t+d) is sent to the users or user group having a trust level d (giving potential access to the service for d consecutive days).

Method for managing and controlling the access keys to services in a communication system

Method and system are disclosed for managing erratic interruptions in a transmission system where the messages to be transmitted are composed of data packets and are expressed by means of a polynomial of degree t&#x2212;1. The senders and the receivers share information making it possible to reference the data packets. In the course of the transmission of a message represented by a polynomial P, at least t points Ai are generated and P(Ai) of the polynomial P is evaluated, with t' greater than or equal to t. The evaluations P(Ai) are transmitted of the t&#x2032; points to the receiver or receivers concerned, with information allowing the receivers to detect the transmission errors. Each receiver verifies that it has received t valid evaluations, that is to say free of transmission errors, uses the information referencing the packets and the t valid evaluations P(Ai) of the polynomial to determine the points Ai, and on the basis of the P(Ai) and of the Ai and determines the polynomial P used and on the basis of said polynomial deduces the message therefrom.

Method and system making it possible to manage erratic interruptions in a transmission system

Device for implementing modular multiplication, characterized in that it comprises at least one computation cell comprising a multiplier-adder comprising p pipelined logic-register pairs, receiving several digits to be added together and multiplied, at least two outputs corresponding to the low order and to the high order, an adder receiving the two outputs of the multiplier-adder, the number p being chosen in such a way that the maximum frequency of the multiplier-adder is greater than or equal to the maximum frequency of the adder.

Method for implementing montgomery modular multiplication and device therefore

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Soisy/Montmorency, France

Eric Garrido