Abstract: The invention relates to a method for the two-factor authentication of a user in an application service running on an application server. The first authentication factor is a PIN authentication code known only by the user and the application service, and the second authentication factor is the mobile communication terminal of the user on which is installed a reliability application obtained from a reliable third party or certified by the same. The reliability application is capable of generating, using the PIN authentication code and a secret key shared only with the reliable third party, a single use authentication code for each authentication of the user in the application service.

Abstract: The invention relates to a method for the digital signature of a message by a signer having an identity and holding a signature device, in which a public key cryptographic scheme is used. The signer has a public key and two private keys, the second private key being deposited at a reliable third party. For each signing operation, two additional steps are respectively carried out with a separate private key, i.e.: the calculation by the signer of a pre-signature of the message using the first private key, and transmitting the message and the pre-signature to the reliable third party; and the verification by the reliable third party of the pre-signature followed by the calculation by the reliable third party of a signature of the message using the second private key deposited at the reliable third party as well as the pre-signature previously calculated by the signer.

Abstract: The invention relates to a method of sharing a strong secret F between two parties (A, B) previously sharing a weak secret F, this method of sharing combining a symmetric algorithm and an asymmetric algorithm, and consisting in using a fixed exponent e of small size, and in encrypting not the exponent e, but the modulus n, by means of the weak secret f.

Abstract: The invention relates to a method for the digital signature of a message by a signer having an identity and holding a signature device, in which a public key cryptographic scheme is used. The signer has a public key and two private keys, the second private key being deposited at a reliable third party. For each signing operation, two additional steps are respectively carried out with a separate private key, i.e.: the calculation by the signer of a pre-signature of the message using the first private key, and transmitting the message and the pre-signature to the reliable third party; and the verification by the reliable third party of the pre-signature followed by the calculation by the reliable third party of a signature of the message using the second private key deposited at the reliable third party as well as the pre-signature previously calculated by the signer.

Abstract: The invention relates to a method for the two-factor authentication of a user in an application service running on an application server. The first authentication factor is a PIN authentication code known only by the user and the application service, and the second authentication factor is the mobile communication terminal of the user on which is installed a reliability application obtained from a reliable third party or certified by the same. The reliability application is capable of generating, using the PIN authentication code and a secret key shared only with the reliable third party, a single use authentication code for each authentication of the user in the application service.

Abstract: The invention relates to a method of sharing a strong secret F between two parties (A, B) previously sharing a weak secret F, this method of sharing combining a symmetric algorithm and an asymmetric algorithm, and consisting in using a fixed exponent e of small size, and in encrypting not the exponent e, but the modulus n, by means of the weak secret f.