Physical layer security (PLS) is a wireless security paradigm which exploits intrinsic features of wireless channels to enhance communication confidentiality and realize authentication. While extensive studies have been conducted in this area during the past decades leading to fruitful achievements, multiple fundamental problems have not been well addressed, which hinders practical adoption of PLS techniques. To bridge the gap between theory and practice, several techniques are introduced in this talk. First, a new theory is established to connect the error floor of eavesdropper’s decoding process to the security level of the desired signal transmission, which provides a rigorous theoretical framework to evaluate PLS performance. Guided by this theory, an innovative secure transmission architecture is then developed, which combines PLS techniques and cryptographic primitives to realize provable security levels. Finally, the applications perspective of PLS research is examined. While plenty of papers have been published in the PLS field, most studies aimed at solving anti-eavesdropping problems. However, current cryptographic approaches are almost competent for accomplishing this, which makes PLS techniques less attractive to the industries. To deal with this issue, this talk will introduce two scenarios, i.e., secure ranging for contactless car entry and privacy protection for wireless sensing, where higher-layer encryption techniques do not work. For these scenarios, advanced solutions will be presented to show how PLS techniques can be utilized to realize integrity protection and privacy enhancement.