Method for checking integrity of property data relating to a device, the property data comprising a program data record and a configuration data record, by means of a testing device inside a network comprising the device, the testing device and at least one further device having further property data, the further property data comprising a further program data record and a further configuration data record, having the following steps: - provision of the property data and the further property data by a station which is coupled at least to the testing device by means of the network; - evaluation of the property data and the further property data by the testing device with regard to at least identity of the program data record and the further program data record, and allocation of an identification on the basis of an evaluation result; - determination of a parameter (P, PC, PS1), which is suitable for influencing a hash value and a test hash value (H'1) of a hash function, by the testing device, the parameter (P, PC, PS1) being configured on the basis of the identification, and transmission of the parameter (P, PC, PS1) to the device; - calculation of the hash value by the device on the basis of the hash function and a character string, the character string comprising the parameter (P, PC, PS1) and the property data and a sequence inside the character string being able to be predefined, and transmission of the hash value to the testing device; - calculation of the test hash value (H'1) by the testing device on the basis of the hash function and the character string, the character string comprising the parameter (P, PC, PS1) and the property data and a sequence inside the character string being able to be predefined; - confirmation of the integrity of the property data by the testing device if the hash value matches the test hash value (H'1). - provision of the property data and the further property data by a station which is coupled at least to the testing device by means of the network; - evaluation of the property data and the further property data by the testing device with regard to at least identity of the program data record and the further program data record, and allocation of an identification on the basis of an evaluation result; - determination of a parameter (P, PC, PS1), which is suitable for influencing a hash value and a test hash value (H'1) of a hash function, by the testing device, the parameter (P, PC, PS1) being configured on the basis of the identification, and transmission of the parameter (P, PC, PS1) to the device; - calculation of the hash value by the device on the basis of the hash function and a character string, the character string comprising the parameter (P, PC, PS1) and the property data and a sequence inside the character string being able to be predefined, and transmission of the hash value to the testing device; - calculation of the test hash value (H'1) by the testing device on the basis of the hash function and the character string, the character string comprising the parameter (P, PC, PS1) and the property data and a sequence inside the character string being able to be predefined; - confirmation of the integrity of the property data by the testing device if the hash value matches the test hash value (H'1).