Method for verifying the authentic origin of electronic modules of a modular field device in automation technology

A method for verifying the authentic origin of electronic modules of a modular field device in automation technology,

• wherein each manufacturer of an electronic module of the field device classified as trustworthy is assigned a key pair consisting of a public key and a private key, and wherein the public keys of the manufacturers classified as trustworthy are stored in a list in the field device or in a unit communicating with the field device,
• wherein each electronic module of the field device contains, in addition to a suitable key pair characterizing the electronic module as trustworthy and consisting of a public key and a private key, the manufacturer's public key and a manufacturer signature, wherein the manufacturer signature confirms the public key of the electronic module as trustworthy,
• wherein the method has the following method steps:
• when an electronic module is exchanged or added, the field device or the unit communicating with the field device checks:
• whether the exchanged or added electronic module has a key pair and a manufacturer signature,
• whether the public key of the manufacturer of the electronic module is listed in the list with the public keys of the manufacturers classified as trustworthy,
• whether the manufacturer signature matches the manufacturer and the electronic module,
• whether the electronic module is in possession of the correct private key,
• a communication or interaction of the exchanged or added electronic module with the field device or another electronic module relating to the functionality of the field device is permitted if the check is concluded with a positive result.