A method for authenticating a mobile ID, wherein the mobile ID is provided on a user terminal, wherein, firstly, personal information about the user is put into an anonymized form (21, 22, 23) by means of a one-way function known to the user terminal and a first entity and transmitted to the first entity by means of a single mobile ID certificate, wherein, henceforth, a communication exchange between the user terminal and the first entity is designated by means of this mobile ID certificate, wherein, at a later time, the user is provided with an authorization option for transmitting the personal information in non-anonymized form (31, 32, 33) to the first entity, and wherein the first entity uses the non-anonymized personal information thus transmitted to it to carry out a check of its anonymized form (21, 22, 23), wherein the following steps are carried out: • Providing a plurality of personal information about an identity of the user as a plurality of attributes (11, 12, 13); • Calculating first one-way values (21, 22, 23) by means of the known one-way function via a selection of respective attributes from the plurality of attributes (11, 12, 13), wherein said selection uniquely identifies the user; • Generating a unique serial number by the terminal; • Generating the mobile ID certificate with the unique serial number and at least one anonymized information field in which the first one-way values (21, 22, 23) are stored; • Transmitting the mobile ID certificate from the user terminal to the first entity; • Establishing a secure communication channel between the user terminal and the first entity and/or authenticating communication data with the user terminal by the first entity by means of the transmitted mobile ID certificate; • Requesting an authorization by the user on an output unit of the terminal for a transmission of personal information to the first entity; • Authorizing by the user on an input unit of the terminal and transmitting personal information in non-anonymized form (31, 32, 33) to the first entity; • Identifying the user by the first entity by means of second one-way values recalculated with the one-way function and matching them with the first one-way values (21, 22, 23). • Providing a plurality of personal information about an identity of the user as a plurality of attributes (11, 12, 13); • Calculating first one-way values (21, 22, 23) by means of the known one-way function via a selection of respective attributes from the plurality of attributes (11, 12, 13), wherein said selection uniquely identifies the user; • Generating a unique serial number by the terminal; • Generating the mobile ID certificate with the unique serial number and at least one anonymized information field in which the first one-way values (21, 22, 23) are stored; • Transmitting the mobile ID certificate from the user terminal to the first entity; • Establishing a secure communication channel between the user terminal and the first entity and/or authenticating communication data with the user terminal by the first entity by means of the transmitted mobile ID certificate; • Requesting an authorization by the user on an output unit of the terminal for a transmission of personal information to the first entity; • Authorizing by the user on an input unit of the terminal and transmitting personal information in non-anonymized form (31, 32, 33) to the first entity; • Identifying the user by the first entity by means of second one-way values recalculated with the one-way function and matching them with the first one-way values (21, 22, 23).