Item Definition (Security)

Item definition is based on SysML diagrams like Block Definition Diagrams (BDD), Internal Block Diagrams (IBD) or SOX Concept Diagrams (SCD).

For example, a security item may be represented by a BDD and an IBD as shown in the following pictures based on ISO/SAE 21434 annex H headlamp example. The SysML BDD depicts the composition hierarchy of the operational environment including the item, i.e., the head lamp system, whereas the IBD emphasizes the internal structure and how parts are connected.

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Modelling composition hierarchy of operational environment and headlamp system (item) in a BDD

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Modelling the internal structure of the headlamp system (item) in an IBD

To define a TARA item by one or more SysML diagrams, expand the folder DESIGN in the project structure, right-click on folder “Security item”, and select New item to open the New item Dialog:

1. Provide a name

2. Select a standard (ISO 21434 by default)

3. Add a description (optional)

4. Select diagram(s) from the drop-down list

5. Click on Finish.

Outcome: A new item document is generated in folder “Security item”.

The item document consists of an item table and the underlying diagrams as images. To see this content, expand the document structure and click on the table or a diagram icon.

The item table lists all model elements of underlying diagrams organized in groups like System Elements, Functions, etc. Additional information can be given such as a description of an element or an assumption.

An item can be assigned to a TARA document during creation of a new document, or in document properties.