A method for granting a computer system access to physiological data of a registered user of a mobile, portable communication system, which data are stored permanently in a memory system, wherein the communication system comprises a classification module, a processor, a communication interface, and at least one sensor for detecting behaviour-based data for a behaviour-based authentication of a current user to the communication system, wherein the classification module is configured to classify the behaviour of the current user with use of the behaviour-based data, wherein the behaviour-based data comprise physiological data of the current user, which data are intended to be stored permanently in the memory system, if the current user is authenticated as the registered user during the course of the behaviour-based authentication, wherein the communication system is configured to communicate with the computer system via the communication interface, wherein the communication system is also configured to carry out the method for granting access, controlled by the processor, which method comprises: • authentication of the computer system to the communication system with use of the communication interface of the communication system, • behaviour-based authentication of the user to the communication system, wherein the behaviour-based authentication of the user comprises: ∘ detection of behaviour-based data of the current user by the at least one sensor of the communication system, ∘ generation of at least one classification result with use of the classification module and the detected behaviour-based data, ∘ evaluation of the at least one classification result in order to authenticate the user, wherein the evaluation comprises a check as to whether the classification result satisfies a predefined check criterion, wherein a successful authentication of the current user as the registered user comprises satisfaction of the predefined check criterion, • generation, by the mobile, portable communication system, of an authentication signal dependent on the success of the authentication of the computer system and of the user, • granting of access for the computer system to the physiological data of the registered user stored permanently in the memory system, if the authentication signal indicates a successful authentication of the computer system and of the current user and if the user has consented to the access. • authentication of the computer system to the communication system with use of the communication interface of the communication system, • behaviour-based authentication of the user to the communication system, wherein the behaviour-based authentication of the user comprises: ∘ detection of behaviour-based data of the current user by the at least one sensor of the communication system, ∘ generation of at least one classification result with use of the classification module and the detected behaviour-based data, ∘ evaluation of the at least one classification result in order to authenticate the user, wherein the evaluation comprises a check as to whether the classification result satisfies a predefined check criterion, wherein a successful authentication of the current user as the registered user comprises satisfaction of the predefined check criterion, ∘ detection of behaviour-based data of the current user by the at least one sensor of the communication system, ∘ generation of at least one classification result with use of the classification module and the detected behaviour-based data, ∘ evaluation of the at least one classification result in order to authenticate the user, wherein the evaluation comprises a check as to whether the classification result satisfies a predefined check criterion, wherein a successful authentication of the current user as the registered user comprises satisfaction of the predefined check criterion, • generation, by the mobile, portable communication system, of an authentication signal dependent on the success of the authentication of the computer system and of the user, • granting of access for the computer system to the physiological data of the registered user stored permanently in the memory system, if the authentication signal indicates a successful authentication of the computer system and of the current user and if the user has consented to the access.