KeyNote: Trust Management for Public-Key Infrastructures

Summary: KeyNote is application-independent policy database.  The
KeyNote policy language allows both local policies and remote policies
(credentials) to be installed.

Main points:

* KeyNote maintains a database that maps public keys to strings
  describing certain permissions.

  - the identity of the key holder and the semantics of the permission
    string is application-dependent (that is, not defined by KeyNote)

* Policies can be loaded locally, or loaded remotely via credentials.
  In the latter case, a chain of assertions must hold (local policy
  asserts that Bob asserts that Sally asserts that I can read this
  file). 

* Public keys are not directly mapped to action strings.  Rather, keys
  are mapped to filters, which are programs that run in a restricted
  environment (i.e., regular expression matching).