Patent ID: 8132240
Filing Date: 2012-03-06
Classification: G05B

Abstract:
1. A method of executing a protected function of an electric field unit, which comprises the following steps: receiving, in the electric field unit, command data specifying a function call for executing a protected function of the electric field unit; determining, with an identification device of the electric field unit, sender characterization data characterizing a respective sender of the command data and appending the sender characterization data to the command data to form appended command data; receiving the appended command data in a security device of the electric field unit and checking the appended command data to see whether or not an execution of the protected function of the electric field unit specified by the command data is allowed and permission should be granted; and if permission is granted, conveying the command data to the protected function and executing the function by the electric field unit; if permission is not granted, denying execution of the protected function; in case of a session-based communication link between the sender and the electric field unit, the sender-specific data contain key data of the sender; and the identity database allocates the sender characterization data to the key data, wherein for forming a secure communication channel between a data processing device of the sender of the communication data and the electric field unit: a random character sequence is generated by the electric field unit and encrypted with a public key of the sender; the encrypted random character sequence is transferred to the data protection device of the sender; the encrypted random character sequence is decrypted with a private key of the sender by the data protection device of the sender; the decrypted random character sequence is reencrypted with a public key of the electric field unit; the reencrypted random character sequence is transferred back to the electric field unit; the random character sequence is decrypted with a private key of the electric field unit by the electric field unit; the decrypted random character sequence is compared with the initial random character sequence; and the secure communication channel is established when the two random character sequences match.