Partial grant set evaluation from partial evidence in an evidence-based security policy manager

In an evidence based security model that evaluates, using a security policy, multiple pieces of evidence to determine a set of granted permissions, and wherein a piece of evidence is likely to determine whether a first permission is granted, a data structure stored in a computer memory, comprising:

• a first portion corresponding to a first value of the piece of evidence and a plurality of permissions;
• and
• a second portion corresponding to a second value of the piece of evidence and the plurality of permissions,
• wherein the data structure indicates, for each value/permission pair, that the permission is granted, or that the permission is either not granted or unknown.

In an evidence based security model that evaluates multiple pieces of evidence using a security policy to determine a set of granted permissions, and wherein a subset of the multiple pieces of evidence is likely to determine whether a subset of permissions is granted, a method for determining the subset of permissions, comprising steps of:

• (a) prior to receiving a request to determine whether the subset of permissions is granted, evaluating the subset of evidence using the security policy, based on the possible values of evidence contained in the subset of evidence, to determine resultant permissions, wherein the subset of evidence includes less than all of the multiple pieces of evidence;
• (b) storing the results from step (a);
• and
• (c) upon receiving a request to determine whether the subset of permissions is granted, wherein the request comprises an instance of the subset of evidence, querying the stored results to determine whether the subset of permissions is granted.