Abstract: A system for authentication, encryption and/or signing, as well as corresponding devices and methods, that use temporary but repeatable encryption keys uniquely connected to the user and generated from a unique set of input parameters. The system comprises an input device (105) designed to extract predetermined characteristic values from value input by the user, which value is specific to the user, by means of a given algorithm, which algorithm is designed to remove the natural variation in the characteristic values in order to yield an identical set of characteristic values upon input of the same value, and a device (106) designed to generate at least one user specific encryption key comprising said characteristic values.