Method of updating at least one security certificate (21b, 22b, 23b, 26) of a safety circuit (21, 22, 23) of an elevator system, the method comprising: - connecting the safety circuit (21, 22, 23) with a communicator which is capable to communicate with a certification server; - sending from the communicator to the safety circuit (21, 22, 23) a security certificate update request for updating at least one security certificate (21b, 22b, 23b, 26) stored within the safety circuit (21, 22, 23); - the safety circuit (21, 22, 23) sending a public key of a safety circuit security certificate (21b, 22b, 23b) associated with the safety circuit (21, 22, 23) via the communicator to the certification server; - the certification server checking whether the safety circuit security certificate (21b, 22b, 23b) associated with the received public key is included in a data base of known security certificates and not marked as compromised; - in case the safety circuit security certificate (21b, 22b, 23b) associated with the received public key is included in the data base of known safety circuit security certificates (21b, 22b, 23b) and not marked as compromised: sending at least one new security certificate (21c, 22c, 23c, 27) from the certification server via the communicator to the safety circuit (21, 22, 23) and installing the at least one new security certificate (21c, 22c, 23c, 27) on the safety circuit (21, 22, 23); - in case the security certificate (21b, 22b, 23b) associated with the received public key is not included in the data base of known security certificates (21b, 22b, 23b, 24b) and/or marked as compromised: sending a message from the certification server to the communicator indicating that the safety circuit (21, 22, 23) is invalid. - connecting the safety circuit (21, 22, 23) with a communicator which is capable to communicate with a certification server; - sending from the communicator to the safety circuit (21, 22, 23) a security certificate update request for updating at least one security certificate (21b, 22b, 23b, 26) stored within the safety circuit (21, 22, 23); - the safety circuit (21, 22, 23) sending a public key of a safety circuit security certificate (21b, 22b, 23b) associated with the safety circuit (21, 22, 23) via the communicator to the certification server; - the certification server checking whether the safety circuit security certificate (21b, 22b, 23b) associated with the received public key is included in a data base of known security certificates and not marked as compromised; - in case the safety circuit security certificate (21b, 22b, 23b) associated with the received public key is included in the data base of known safety circuit security certificates (21b, 22b, 23b) and not marked as compromised: sending at least one new security certificate (21c, 22c, 23c, 27) from the certification server via the communicator to the safety circuit (21, 22, 23) and installing the at least one new security certificate (21c, 22c, 23c, 27) on the safety circuit (21, 22, 23); - in case the security certificate (21b, 22b, 23b) associated with the received public key is not included in the data base of known security certificates (21b, 22b, 23b, 24b) and/or marked as compromised: sending a message from the certification server to the communicator indicating that the safety circuit (21, 22, 23) is invalid.