Abstract: A method for securing an execution of a local application is provided and includes the steps of requesting, from the first user device, to execute, by the local application, at least one operation; generating, by the first user device, by executing the local application, a first challenge; sending, from the local application, to a second user device, the first challenge and a predetermined identifier relating to an associated key pair; and retrieving, by the second user device, based on the key pair identifier, a private key; generating by the second user device, a first response, by using the first challenge and the private key; and sending from the second user device to the local application, the first response. Other embodiments are disclosed.

Abstract: The present invention relates to a method to handle the authentication of a user of a device with an operator, said operator needing a user identifier for the purchase of additional element of an application installed in the device, said method implemented by a dedicated client component of the application. The invention also concerns an authentication server, a device and a software development kit to implement the method within an application in a device.