Bull S.a.

Denis Pinkas

Philippe Caille

For a set (Lk) of embedded systems, an authorized operator with identifier (OP) creates a mother public key (KpM) and a mother private key (KsM). The identifier (OP), the range of identifiers referenced (Lk) and the mother public key (KpM) are published. For each embedded system (SN), a diversified key (KsM) is created from the identifier (SN) and stored. For every public key (Kp) generated by an embedded system, a cryptographic control value (Sc) is calculated on the public key (Kp), an algorithm identifier (CA) and the utilization parameters (U) of this key, using a zero knowledge signature algorithm, and a certification request message (MRCA) that includes control value (Sc), the identifier of the operator (Op), and identifier (SN) is transmitted to a certification authority, which retrieves the identifier (Op) and the value of the mother public key (KpM).

Method for verifying the use of public keys generated by an on-board system

The present invention relates to a key recovery process used for strong encryption of a message sent by an entity, which message is either to be stored locally or transmitted to another entity, the reading of a message requiring a decryption key which can be reconstructed at least by a trusted third party for key recovery, while added to the message are a compensation field and a compulsory control field which itself comprises at least one key recovery field for allowing at least one trusted third party to supply the decryption keys that enable the encrypted message to be read. This key recovery process is remarkable in that the compulsory control field also comprises, in unencrypted form, the current date as well as the agreement number of the encryption hardware/software and, encrypted under a daily intermediate key, the dialogue key. This key recovery field also comprises, first of all, the identifier of the appropriate trusted third party for key recovery, as a function of the application type, followed by a dialogue key encrypted under the public key or said trusted third party, and lastly, encrypted under the public key of said trusted third party, the serial number of the approved hardware/software and optionally the identifier of the entity and its manager, a working key being used to calculate the daily intermediate key and the period of validity of said working key. Finally, and equally remarkably, during the period of validity of the working key, said working key makes it possible, with only the compulsory control field having been supplied, to calculate in advance for the time period for which the eavesdropping has been authorized, by means of a prescribed formula, daily intermediate keys used to decrypt the dialogue keys, which are themselves used to calculate, from the compensation field and the compulsory control field, the random keys for decrypting the messages.

Key recovery process used for strong encryption of messages

The present invention relates to a process for verifying the preservation of the integrity of an unprotected request sent by an anonymous client to a server, in which only one public key, that of the server, is used. This process is remarkable in that the anonymous client sends, along with his request, a flag which specifies whether or not the server must offer an absolute guarantee of non-repetition of the requests received as well as a unique number, that is, a number which never repeats or has a low probability of repetition, consisting either of a random number with a low probability of repetition or the concatenation of a time indicator and a random number with a certainty of non-repetition, the verification of said integrity being performed during the reception of the response to the request, for which reason the global response includes the response to the request plus the result of a one-way compression function applied to the request, flag and unique number combination, the integrity of the global response moreover being protected either by means of the public key of the server used as a signature key, or by means of a private key established using the public key of the server as an encryption key.

Process for verifying the preservation of the integrity of an

A method for authenticating a user working in a distributed environment in the client/server mode, wherein each authentication is performed from a single piece of authentication information, known as the 'passphrase', having a predetermined length and duration of use (as a function of a tally value). The method is applicable to either a one-time password (OTP) system or an OTP system integrated with a Kerberos system, or in a one-time password system used alone, and the method may be used from a trusted terminal or an untrusted terminal. A method is provided that enables reinitializing the 'passphrase' at the end of the duration of use with security, even in the event of active interception, and either in an OTP system integrated with a Kerberos system, or in an OTP system used alone.

Method for authenticating a user working in a distributed environment in

A method for obtaining at least one securitized cleartext attestation by at least one requestor subject coupled to a data processing system and communicating with each other through a network. The data processing system includes a plurality of subjects and an authority represented by at least one server acting on behalf of the authority and issuing attestations. The requestor subject sends the authority an attestation request including at least one protection datum. The requestor subject chooses, at random, a check datum which is associated and linked with the protection datum. The requestor subject then transmits, in cleartext, to the authority both a piece of identification information defining the relationship between the check datum and the protection datum, and the protection datum itself. The server organizes the attestation in the form of binary information and calculates at least one of a signature and a seal of attestation taking into account the protection datum and the identification information. The server then transmits the sealed or signed attestation, in cleartext, to the requestor subject A method for providing a chaining value for the check datum when multiple subjects request sequential attestation of a message is also provided.

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Chaville, France

Denis Pinkas