An identification server for identifying a person to be identified on the basis of a transformed biometric reference feature which is assigned to the person to be identified, the identification server comprising: a memory in which a transformation rule is stored; a communication interface which is configured to send out a request for transmission of a biometric feature of the person to be identified as well as a transformation key via the communication network, and which is configured to receive the biometric feature of the person to be identified as well as the transformation key via the communication network; and a processor which is configured to transform the received biometric feature of the person to be identified by the transformation rule and the received transformation key into a transformed biometric feature for an identification on the basis of the transformed biometric reference feature, wherein the communication interface is further configured to send out the generated transformed biometric feature via the communication network to a service server of a service provider for a comparison of the transformed biometric feature with the transformed biometric reference feature, wherein the communication interface is further configured to receive a person identifier transmitted by the service server of the service provider via the communication network, wherein the person identifier is assigned to the person to be identified, and wherein the communication interface is further configured to send out the request for transmission of a biometric feature of the person to be identified as well as a transformation key via the communication network in response to receiving the person identifier. a memory in which a transformation rule is stored; a communication interface which is configured to send out a request for transmission of a biometric feature of the person to be identified as well as a transformation key via the communication network, and which is configured to receive the biometric feature of the person to be identified as well as the transformation key via the communication network; and a processor which is configured to transform the received biometric feature of the person to be identified by the transformation rule and the received transformation key into a transformed biometric feature for an identification on the basis of the transformed biometric reference feature, wherein the communication interface is further configured to send out the generated transformed biometric feature via the communication network to a service server of a service provider for a comparison of the transformed biometric feature with the transformed biometric reference feature, wherein the communication interface is further configured to receive a person identifier transmitted by the service server of the service provider via the communication network, wherein the person identifier is assigned to the person to be identified, and wherein the communication interface is further configured to send out the request for transmission of a biometric feature of the person to be identified as well as a transformation key via the communication network in response to receiving the person identifier.