1. An apparatus comprising a processor operable to: receive a token that indicates a change that occurs during a session, wherein the session facilitates access to a resource, the token indicating a risk token should be computed; determine, from the token, a first set of attributes, the first set of attributes comprising attributes required to compute the risk token; determine that a cache contains a set of cached attributes; examine an attribute in the set of cached attributes; determine the attribute in the set of cached attributes is not in the first set of attributes; remove the attribute from the cache.