As increased use of data mining technology becomes popular, data mining technique, which has information protection capability, is required in several areas. Business data owners do not want to release business specific information to another party since it may generate economic loss to business data owner when third-party companies can analyze their data for the purpose of mining interesting patterns or finding business information. Many works have been done to efficiently discover maximal frequent patterns from a large database. However, most of existing works do not consider information protection during mining process. In this paper, we propose an efficient approach for mining maximal frequent patterns from a large transactional database with the capability of information protection. Our approach uses prime number based encryption method for information protection and utilizes lattice structures to find maximal frequent patterns in time and memory efficient manner. Extensive experimental results show that our approach can find accurate results within an acceptable time with information protection capability.