Hardware security has become more and more important in current information security architecture.Recently collected reports have shown that there may have been considerable hardware attacks prepared for possible military usage from all over the world.Due to the intrinsic difference from software security,hardware security has some special features and challenges.In order to guarantee hardware security,academia has proposed the concept of trusted integrated circuits,which aims at a secure circulation of IC design,manufacture and chip using.This paper reviews the main problems of trusted integrated circuits,and concludes four key domains of the trusted IC,namely the trusted IC design,trusted manufacture,trusted IP protection,and trusted chip authentication.The main challenges in those domains are also analyzed based on the current known techniques.Finally,the main limitations of the current techniques and possible future trends are discussed. Hardware security has become more and more important in current information security architecture.Recently collected reports have shown that there may have been probably hardware attacks prepared for possible military usage from all over the world.Due to the intrinsic difference from software security, hardware security has some special features and challenges. In order to guarantee hardware security, academia has proposed the concept of trusted integrated circuits, where aims in a secure circulation of IC design, manufacture and chip using. This paper reviews the main problems of trusted integrated circuits, and concludes four key domains of the trusted IC, namely the trusted IC design, trusted manufacture, trusted IP protection, and trusted chip authentication.The main challenges in those domains are also based on the current known techniques. Finally, the main limitations of the current techniques and possible future trends are discussed.