Heads or tails: Experimental quantum coin flipping cryptography performs better than classical protocols
(Phys.org) —Cryptography – the practice and study of techniques for secure communication in the presence of third parties, referred to as adversaries – has a long and varied history. In ancient Greece, for example, the Spartan military may have used the so-called scytale transposition cipher to encrypt and decrypt messages. Steganography (hiding the existence of a message) was also first developed at that time as, according to Herodotus, a message tattooed on a slave's shaved head and then hidden under regrown hair – and is still in use in the form of invisible ink, microdots, and digital watermarks. That said, applying complexity cryptography to quantum communication is and will continue to be essential – and while quantum cryptographic primitives are in principle more secure than classical protocols, demonstrating this in a practical system has proven difficult.