The present invention provides a computing device including a system ranking unit, a subset ranking unit, an evaluation module of computing units and a decision module. The system ranking unit is configured to rank at least one or more elements to acquire a first ranking based on features of at least one set of data. The subset ranking unit is configured to select a subset from the elements, and is configured to re-rank elements in the subset to acquire a second ranking. The computing units are configured to calculate a relevance of consistency between the first ranking and the second ranking, and are configured to calculate a second rating associated with a first identification message. The decision module is configured to determine a data access level of the first identification message, and configured to access the data based on the data access level.