API's (and REST API's) need to be carefully protected through mechanisms limiting access on the basis of identity and authorizing and authenticating through managed and controlled mechanisms. Usually certificates and IP-addresses are being used to restrict access to API's, but a more granular approach is advisable from a Security Architecture perspective. Other architectures being used as Integratio Protocols in Digital Manufacturing Platforms are JSON (for its near real time capabilities) and MQ (message bus architectures). The letter being less secure, since it provides a continuous stream of information which is being sent to a destination.
Authorisation is the process of allowing an entity (humans, systems or devices) to access information systems or facilities where information and processing capabilities are being stored. More practical in an industrial setting for Digital Manufacturing Platforms, an authorized person can get access to an operational machine in order to update it, or investigate its contents. Unauthorized access could be someone who has been able to access the network from the outside, performing actions that have not been authorized and cannot be justified.
Authentication is a means to assess the authorization rules of an entity by means of a set of instruments. In the case of Digital Manufacturing Platforms it would be the instruments like user name and password, and in addition a second factor such as a physical token or a mobile phone that can authenticate the person accessing the platform. The physical token connects the person to something he has, the password to something he knows.
A third A in the AAA-architecture is related to Access. Once authorized, and authenticated, access can be granted to the location, system, application, and / or information. Access control levels can thus be set up on different layers. These can be physical (access to the country, to the plant, to the building, the room and the environment where the system is located), and logical (using authentication technologies). In Digital Manufacturing Platforms this means the systems could be accessible only on premise, in the factory or for instance in the (private or public) cloud. As a result different access mechanisms needs to be considered, depending on the risk and intended security levels and controls.
Federal Ministry of Economic Affairs and Energy -Alignment Report for Reference Architectural Model for Industrie4.0 / Intelligent Manufacturing System Architecture. Sino-German Industrie4.0 / Intelligent Manufacturing. Standardisation Sub-Working Group
On the right horizontal axis of RAMI 4.0 are the hierarchy levels from IEC 62264, the international standards series for enterprise IT and control systems. These hierarchy levels represent the different functionalities within factories or facilities. The IEC 62264 standard is based upon ANSI/ISA-95. To represent the Industry 4.0 environment, these functionalities have been expanded to include work pieces, labeled 'Product', and the connection to the Internet of Things and services, labeled 'Connected World'. (From https://www.isa.org).
The Asset Administration Shell (AAS) is the digital representation of an asset. The AAS consists of a number of submodels in which all the information and functionalities of a given asset – including its features, characteristics, properties, statuses, parameters, measurement data and capabilities – can be described. It allows for the use of different communication channels and applications and serves as the link between objects and the connected, digital and distributed world. (From 'Asset Administration Shell Reading Guide (As Of April 2021)')
The overall concept is the use of the Admnistrative Asset Shell (AAS). It is requesting access to an object. In the context of an AAS an object typically is a submodel or a property or any other submodel element connected to the asset. The implemented access control mechanism of the AAS evaluates the access permission rules (2a) that include constraints that need to be fulfilled w.r.t. the subject attributes (2b), the object attributes and the environment conditions (2d). The focus is on access control. An object in the context of ABAC corresponds typically to a submodel or to a submodel element. The object attributes again are modelled as submodel elements. Subject Attributes need to be accessed either via an external policy information point or they are defined as properties within a special submodel of the AAS. A typical subject attribute is its role. The role is the only subject attribute defined in case of role based access control. Optionally, environment conditions can be defined. In role based access control no environment conditions are defined. Environment conditions can be expressed via formula constraints. To be able to do so the values needed should be defined as property or reference to data within a submodel of the AAS.