Method for cryptographically verifiable identification of a physical unit in a public, wireless telecommunications network

A mobile telephone for use in an open, wireless telecommunications network, comprising:

• a non-volatile memory;
• an identity module configured to:
• store a mobile phone secret identity and store a mobile phone open identity in the non-volatile memory in the mobile telephone, the mobile phone secret identity being an encryption of the mobile phone open identity;
• receive an identity request with a first parameter from a testing device;
• generate an electronic signature by means of a first cryptographic function from the secret identity and at least the first parameter in the mobile telephone, and send the generated electronic signature and the open identity to the testing device;
• wherein the secret identity is such that the open identity of the mobile telephone is confirmed if the electronic signature matches a corresponding electronic signature generated by the testing device by application of a the first cryptographic function to the secret identity.