The Confinement Problems

<<Perimeter<< Up to Leakage >>Confused Deputy>>
Mallet and Bob are not supposed to be able to communicate.  However, both Bob and Mallet wish Mallet to have the power.  The Confinement Problem is ensuring that Bob and Mallet are indeed separated despite their joint efforts to communicate.

See the original paper.
Information
(bits)
Authority
(capabilities)
Leakage Out Wall Banging
Limiting Bandwidth
Authority Out
Leakage In Durability
Non-Determinism
Authority In
Alice is safe if Alice knows Bob is in a sealed box. Software confinement requires primitives for constructing a virtual sealed box. Confinement is not all or nothing. Capability systems at least distinguish these four types of leakage across the box's boundary. Whether this breakdown is natural for confinement in non-capability systems remains to be seen. Password capability systems can't separate the leakage of authority from the leakage of info. Other capability systems can.