This paper investigates authentication and secure data retrieval issues in Radio-Frequency IDentification (RFID)-aware wireless sensor networks. We propose a network architecture (ARIES) consisting of RFIDs and wireless sensor nodes, a mutual authentication protocol (AMULET), and a Secret Search Protocol (SSP). ARIES utilises RFID-aware sensor nodes to alleviate distance limitation problem in RFID systems. AMULET performs mutual authentication and reduces the cost of re-authentication. SSP solves the privacy problem by offering a search mechanism over encrypted data. SSP does not need to decrypt encrypted data files while searching for specific data and the performance is greatly improved.