An industrial automation system is provided. This includes at least one license component that is granted by a third party to permit access to a portion of an industrial control component. At least one protocol component that is based in part on a private key exchange facilitates authentication and access...http://www.google.com.hk/patents/US8015409?utm_source=gb-gplus-share專利 US8015409 - Authentication for licensing in an embedded system
