Security and Joint Action

[Francis McCabe <fmccabe@gmail.com>]

When considering the security of interaction two thoughts seem to be  
important.

Issue number one is: "is what is going on what every expects is going  
on?"
Issue number two is: "is what is going on what is supposed to be gong  
on?"

Both of these questions go well beyond security. However, in the  
domain of secure interaction, the first is addressed in terms of  
integrity, confidentiality and authentication: i.e., are the players  
who we think they are and do we have the perimeter secured?

The second speaks to authorization: do the players have the  
appropriate authority to be doing what they are doing.

As a matter of interest, the first is sometimes captured in terms of  
the *validity* of an action or actions (including joint actions) and  
the second is captured in terms of the *empowerment* of the actors. We  
may not need to bring the concepts of validity and empowerment into  
the secure interactions diagram; but they should inform us in our  
design of the diagram.

Note: joint actions show up in multiple levels in a given interaction.  
Security also shows up in multiple levels. The concept of message does  
not appear in all those levels -- only some.