[examples]

A simple policy:

  $ cpabe-enc pub_key security_report.pdf 'foo and (bar or bif)'

A complex policy specified on stdin:

  $ cpabe-enc pub_key security_report.pdf
.br
  (sysadmin and (hire_date < 946702800 or security_team)) or
.br
  (business_staff and 2 of (exec_level >= 5#4, audit_group, strat_team))
.br
  ^D

[policy language]

Policies are specified using simple expressions of the attributes
given to cpabe-keygen (1). The most basic policy consists of a single
such attribute. It will only match keys produced by giving that
attribute (possibly among others) to cpabe-keygen (1).

Another type of policy consists of a comparison between an attribute
name and a non-negative integer. The following comparisons are
allowed: `<', `>', `<=', `>=', and `='. In this case, the attribute
used must be a numerical attribute and specified appropriately to
cpabe-keygen (1) (see its man page for details). Note that a
comparison with an explicit length integer (e.g., "exec_level >= 5#4")
can only match an attribute with the same length (so "exec_level =
8#4" will match but "exec_level = 8#5" will not).

Policies of these two basic types may be combined using the the
keywords `and' and `or' (which may not be used as attributes), as
shown in the first example above. The `and' operator has higher
precedence than `or', and parenthesis may be used to specify other
groupings.

Policies may also be combined using a threshold gate operator, written
as `K of (P1, P2, ... PN)', where K is a positive integer less than or
equal to N, and P1, ... PN are policies. Such a policy will only be
satisfied by a key that satisfies at least K of the policies P1, ...
PN. An example of the threshold gate operator is included as part of
the policy in the second example above.

Note that attribute names are case sensitive and must begin with a
letter, and the keywords `and', `or', and `of' may not be used. Also,
`&' and `|' are synonyms for `and' and `or'.

[see also]
.BR cpabe-setup (1),
.BR cpabe-keygen (1),
.BR cpabe-dec (1)