Quantum technologies are today a reality, and they have been applied to different subjects, such as computing, communication, sensing and randomness generation. This thesis work will focus on two of them in particular: Quantum Key Distribution (QKD) protocols, that allow two parties to exchange a cryptographic key with unconditional security and Quantum Random Number Generators (QRNG), that allow to generate sequences which are not only uniformly distributed but also private and unforeseeable by any other observer. In my work I studied these subjects both theoretically and experimentally. This work is focused on one side on the study of the security for simplified and efficient QKD protocols and on the other side to investigate the implementation of newly developed protocols for semi-device-independent quantum random number generators, that need few assumption to prove their quantum nature, but could still be implemented with a simple set-up.