Method for controlling access of a terminal to an attribute stored in a mobile phone (100, 800, 802), wherein the mobile phone (100, 800, 802) comprises a first mobile radio interface, a first communication interface, and an application which is configured to control the mobile phone (100, 800, 802) in order to carry out the method, wherein the method comprises authentication of the terminal by the mobile phone (100, 800, 802) and authentication of the mobile phone (100, 800, 802) by the terminal, wherein the mobile phone (100, 800, 802) comprises a chip card operating system, and wherein the application is a chip card application which is executable on the chip card operating system, wherein the chip card operating system is installed on a security module of the mobile phone (100, 800, 802) and the chip card application is executed on the chip card operating system of the security module, wherein the authentication of the terminal by the mobile phone (100, 800, 802) comprises: - sending a first access token from the terminal to the mobile phone (100, 800, 802), - verifying, by the mobile phone (100, 800, 802), a first signature of the first access token using a static public key associated with the terminal, - generating and sending a session-based temporary public key by the terminal to the mobile phone (100, 800, 802), - generating and sending a random first secret by the mobile phone (100, 800, 802) to the terminal, - creating a second signature of the random first secret using a static private key associated with the terminal and using the session-based temporary public key of the terminal, - sending the second signature by the terminal to the mobile phone (100, 800, 802), - verifying the second signature of the random first secret by the mobile phone (100, 800, 802) using the random first secret, the session-based temporary public key of the terminal and the static public key associated with the terminal, - following successful verification of the first and second signature, releasing the access of the terminal to the attribute, wherein the access of the terminal to the attribute is provided only on the condition of successful authentication of the mobile phone (100, 800, 802) by the terminal, wherein the authentication of the mobile phone (100, 800, 802) comprises: - sending, to the terminal, a public key of the mobile phone (100, 804) and a domain parameter associated with the public key, - calculating, by the mobile phone (100, 804), a second secret, which is common to the mobile phone (100, 804) and the terminal, from a private key of the mobile phone (100, 804), the session-based temporary public key of the terminal, and the domain parameter, - calculating, by the terminal, the common second secret from the public key of the mobile phone (100, 804), the session-based temporary private key of the terminal, and the domain parameter, - generating a random third secret by the mobile phone (100, 804), - sending the random third secret to the terminal, and - generating, by the mobile phone (100, 804) and the terminal, a symmetric session key from the third secret and the common second secret, wherein the subsequent communication, with the access to the attribute, occurs in an encrypted manner by the symmetric session key, wherein the mobile phone (100, 804) communicates by means of its mobile radio interface via a digital cellular mobile phone network with a remote maintenance server, which provisions the cryptographic key, which comprises the private key of the mobile phone (100, 804) and is associated with the mobile phone, via a mobile phone number of the mobile phone (100, 804) known to the remote maintenance server. - sending a first access token from the terminal to the mobile phone (100, 800, 802), - verifying, by the mobile phone (100, 800, 802), a first signature of the first access token using a static public key associated with the terminal, - generating and sending a session-based temporary public key by the terminal to the mobile phone (100, 800, 802), - generating and sending a random first secret by the mobile phone (100, 800, 802) to the terminal, - creating a second signature of the random first secret using a static private key associated with the terminal and using the session-based temporary public key of the terminal, - sending the second signature by the terminal to the mobile phone (100, 800, 802), - verifying the second signature of the random first secret by the mobile phone (100, 800, 802) using the random first secret, the session-based temporary public key of the terminal and the static public key associated with the terminal, - following successful verification of the first and second signature, releasing the access of the terminal to the attribute, - sending, to the terminal, a public key of the mobile phone (100, 804) and a domain parameter associated with the public key, - calculating, by the mobile phone (100, 804), a second secret, which is common to the mobile phone (100, 804) and the terminal, from a private key of the mobile phone (100, 804), the session-based temporary public key of the terminal, and the domain parameter, - calculating, by the terminal, the common second secret from the public key of the mobile phone (100, 804), the session-based temporary private key of the terminal, and the domain parameter, - generating a random third secret by the mobile phone (100, 804), - sending the random third secret to the terminal, and - generating, by the mobile phone (100, 804) and the terminal, a symmetric session key from the third secret and the common second secret,