User activities are normally in variant forms or may be aberrant in some cases.This kind of uncertainty leads to the difficulty for current intrusion detection algorithm in deciding whether the user is masquerading or not.In the proposed algorithm

the user features are properly selected and the corresponding user trustworthiness computation methods are introduced.Different types of trustworthiness are integrated with interval type-2 fuzzy set

thus user trustworthiness is got and applied to a threshold-based decision.Theory analysis and experiments show that the proposed algorithm can handle the uncertainties that exist in user actirity or user model

so better detection performance can be achieved

compared with the detection algorithm based on ordinal fuzzy set.