Radio frequency identification (RFID) systems have recently been used in a large number of applications. Security and privacy issues have also imposed significant challenges on these systems. Cryptography and authentication protocols have been utilized to effectively solve the security and privacy problems in RFID systems. In this paper, we integrate public key encryption, embedded computation, and wireless communication technologies into the active RFID system that we proposed with cryptography and authentication mechanisms. In our proposed active RFID system, a secure RFID Tag intermittently transmits cipher text to a RFID Reader which then transmits in multi-hop relaying to a back-end platform to perform data comparison for authentication. In addition, the digital signature scheme – Tame Transformation Signatures (TTS) has the advantages of high security, high-speed key generation, signature, and suitability to embedded systems and is thus suitable to be used in our authentication system. It is used in our proposed system to protect the plain text. The TTS algorithm is from the family of asymmetric public key systems and thus has superiority such as better security, fast key generation, complex algorithm, and low signature delay. The TTS algorithm can thus encrypt data and perform authentication more effectively in active RFID systems. We have three major contributions in this paper. The first is to fully design and implement an active RFID system which includes active Tags and Readers. In our system, the Tag can stand by and keep working in long term after getting started. The second is to successfully implement a proposed active RFID system with TTS cryptography and authentication mechanisms to protect the content in tags to ensure the security in multi-hop transmission. The last is to adopt multi-hop relays to extend distance between Readers.