[cap-talk] Capabilities in C# (revised)

Mark Miller erights at gmail.com
Fri Nov 3 16:40:37 CST 2006

On 11/3/06, Karp, Alan H <alan.karp at hp.com> wrote:
> > Perhaps you could clarify how to explain what a "side channel" is, as
> > this will give me a better idea how to explain it.
> Objects communicate by sending messages to other objects.  These
> messages can convey data and references to other objects.  That's the OO
> communications channel.  I call anything else a side channel.

I call anything else, "non-object causality". I'd certainly be happy
to have better terminology. However, I only use the term "side
channel" for non-overt causal channels. A Java mutable static variable
is overt, but is a non-object-based causal channel. Ambient authority
is also a form of non-object authority, but not all non-object
authority is ambient.

Further terminology distinctions:

*Authority* includes only those effects that can be caused using overt
causality. For effects that can be caused by overt or covert
causality, I use "ability".

Non-overt channels include both side-channels and covert channels. The
difference between these is only whether the entity emitting the
non-overt signal intends to be encoding the information that leaks
over that channel.

Text by me above is hereby placed in the public domain


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