The talk discusses the evolution of cryptographic and other privacy-enhancing technologis from a historical point of view, until the development of the so-called end-to-end encryption implemented in modern messaging applications. It also discusses some of the approaches proposed to intercept communications in such platforms, their fundamental limitations and corresponding impact on security. The goal is to demystify the current debate around cryptography and suggest concrete ways to perform criminal investigation using encrypted data but without compromising the security of communication infrastructures.