Physical security mechanisms are employed by cryptographic modules where the protection of the modules sensitive security parameters is desired. ISO/IEC TS 30104:2015 addresses how security assurance can be stated for products where the risk of the security environment requires the support of such mechanisms. This Technical Specification addresses the following topics: - a survey of physical security attacks directed against different types of hardware embodiments including a description of known physical attacks, ranging from simple attacks that require minimal skill or resources, to complex attacks that require trained, technical people and considerable resources; - guidance on the principles, best practices and techniques for the design of tamper protection mechanisms and methods for the mitigation of those attacks; and - guidance on the evaluation or testing of hardware tamper protection mechanisms and references to current standards and test programs that address hardware tamper evaluation and testing. The information in ISO/IEC TS 30104:2015 is useful for product developers designing hardware security implementations, and testing or evaluation of the final product. The intent is to identify protection methods and attack methods in terms of complexity, cost and risk to the assets being protected. In this way cost effective protection can be produced across a wide range of systems and needs.