Abstract: A method for confidentially querying the presence of a record in a database hosted by a server, the records being stored in the database in the form of digital footprints obtained by hashing a record by a public hash function. The footprints are masked by a stream cipher using a symmetric key of a first user. The first user may grant a second user authorisation to query the database by transmitting the inverse masks of various rows, encrypted by the public key of an additive homomorphic cryptosystem of the second user. The rows of the database are unmasked in the homomorphic domain and the second user transmits an encrypted request to query the base according to a PIR protocol. The second user can decrypt the response from the server using the private key of their homomorphic cryptosystem and determine whether the footprint sought is present in the response thus decrypted.

Abstract: The present invention concerns a method for secure data classification by a computer platform. A client sends to the platform data to be classified in encrypted form using a first symmetric key. Similarly, a supplier sends to the platform parameters of a classification model in encrypted form using a second symmetric key. The invention uses a homomorphic cryptosystem defined by a public key and a private key. The platform performs a first transcryption step by deciphering the data to be classified in the homomorphic domain and a second transcryption step by deciphering the model parameters in the homomorphic domain. The classification function is then evaluated in the homomorphic domain for providing a classification result encrypted by said public key.

Abstract: The present invention concerns a method for confidentially processing the kinematic data of a vehicle (210), in particular a method for classifying this data in order to determine the driving style of the vehicle while respecting the confidentiality of the data in question. The data is encrypted (254) by the vehicle by means of a symmetric encryption algorithm using a secret key generated (251) by the vehicle. This secret key is encrypted (252) by the vehicle by means of a homomorphic asymmetric encryption algorithm by using the public key of a vehicle service provider (240). The data encrypted by means of the secret key, and the homomorphically encrypted secret key, are transmitted (253, 255) by the vehicle to an access point that transcrypts (261) them and transmits (262) the homomorphically encrypted data to a calculation platform (230).

Abstract: The present invention concerns a method for processing system logs of a computer system. A system log generator (LG) transmits these system logs to a system log analyser (SIEM) after they have been encrypted by means of a symmetric encryption key and sends the symmetric encryption key in parallel with a homomorphic cryptosystem public key. The system log analyser carries out a transcryption of these logs then a processing thereof in the homomorphic domain. The result of the processing in the homomorphic domain is then transmitted to a security centre (SOC) or even directly to the system log generator to be decrypted there. The security centre can establish a security report or propose a countermeasure before sending it, in form encrypted by the symmetric key, to the system log generator.

Abstract: A method for confidentially querying an encrypted database hosted by a server. The user transmits, to the server, a request including a predicate. The predicate is evaluated in an encrypted manner on different records of the database. The records that satisfy the query are transferred blindly into a container. The container is transmitted to the user who decrypts the content of same. If the container is full, the user sends a continuation request to the server. If this is not the case, the records of the successive containers that have already been decrypted form the response to the request.

Abstract: A method allowing a user confidentially to query a server including a database. The user builds, from an index of a desired entry, a vector encrypted by a homomorphic probabilistic cryptosystem, and transmits a request having the vector as an argument to the server. The server performs a scalar product between the vector of entries of the database and returns the result to the user. The user decrypts the scalar product to obtain the desired entry. The method can be used for example for querying a location-based service and for navigation by concealed routes.

Abstract: The present invention concerns a method for secure data classification by a computer platform. A client sends to the platform data to be classified in encrypted form using a first symmetric key. Similarly, a supplier sends to the platform parameters of a classification model in encrypted form using a second symmetric key. The invention uses a homomorphic cryptosystem defined by a public key and a private key. The platform performs a first transcryption step by deciphering the data to be classified in the homomorphic domain and a second transcryption step by deciphering the model parameters in the homomorphic domain. The classification function is then evaluated in the homomorphic domain for providing a classification result encrypted by said public key.

Abstract: A method for confidentially querying an encrypted database hosted by a server. The user transmits, to the server, a request including a predicate. The predicate is evaluated in an encrypted manner on different records of the database. The records that satisfy the query are transferred blindly into a container. The container is transmitted to the user who decrypts the content of same. If the container is full, the user sends a continuation request to the server. If this is not the case, the records of the successive containers that have already been decrypted form the response to the request.

Abstract: A method allowing a user confidentially to query a server including a database. The user builds, from an index of a desired entry, a vector encrypted by a homomorphic probabilistic cryptosystem, and transmits a request having the vector as an argument to the server. The server performs a scalar product between the vector of entries of the database and returns the result to the user. The user decrypts the scalar product to obtain the desired entry. The method can be used for example for querying a location-based service and for navigation by concealed routes.