Method for authenticating, on a server device of a telecommunications network, a telecommunications terminal comprising an identity module, wherein identity information uniquely allocated to the identity module is used for the authentication using the properties of an asymmetric cryptographic method, wherein a first key pair comprising a first public key and a first private key is allocated to the identity module, wherein a second key pair comprising a second public key and a second private key is allocated to the server device, characterised in that the method comprises the steps of: - in a first method step, in a storage region of the identity module - the first private key is stored, - the first public key is stored and - a first signature is stored, wherein the first signature is provided by signing the first public key by means of the second private key according to the cryptographic method, - in a second method step, the identity information uniquely allocated to the identity module is generated by the identity module and a second signature is generated, wherein the second signature is provided by signing the identity information by means of the first private key according to the cryptographic method, - in a third method step, the first public key, the identity information and the first and second signature are transmitted to the server device, - in a fourth method step, by means of the server device - the authenticity of the first public key is verified by means of the second public key and - the authenticity of the identity information is checked by means of the verified first public key; wherein the identity information comprises International Mobile Subscriber Identity (IMSI) information of the identity module. - in a first method step, in a storage region of the identity module - the first private key is stored, - the first public key is stored and - a first signature is stored, wherein the first signature is provided by signing the first public key by means of the second private key according to the cryptographic method, - the first private key is stored, - the first public key is stored and - a first signature is stored, wherein the first signature is provided by signing the first public key by means of the second private key according to the cryptographic method, - in a second method step, the identity information uniquely allocated to the identity module is generated by the identity module and a second signature is generated, wherein the second signature is provided by signing the identity information by means of the first private key according to the cryptographic method, - in a third method step, the first public key, the identity information and the first and second signature are transmitted to the server device, - in a fourth method step, by means of the server device - the authenticity of the first public key is verified by means of the second public key and - the authenticity of the identity information is checked by means of the verified first public key; - the authenticity of the first public key is verified by means of the second public key and - the authenticity of the identity information is checked by means of the verified first public key;