Code-makers and code-breakers have been competing for supremacy for thousands of years. With the rise of the internet, the importance of communication security is growing. Quantum mechanics, more precisely, quantum key distribution (QKD), promises unconditional security based on the laws of physics, thus achieving the Holy Grail of communication security. Here, I survey the theory and practice of QKD. Moreover, I discuss about recent new research efforts on quantum hacking and counter-measures about it. Furthermore, I will briefly survey i) how quantum computing will break completely the security of bit-coin, ii) the recent ground to satellite quantum communication experiments and iii) the US government agency NIST (National Institute of Standards and Technology)’s current effort to standardize post-quantum crypto-systems.