Attack on classical cryptography system raises security questions

(Phys.org)—How secure is completely secure? In the world of secure communication, a scheme may be completely secure until it's not—that is, until an attack is proposed that reveals a weak spot in the scheme. This is what's currently going on for Kish key distribution (KKD), which claims to derive total and unconditional security using classical rather than quantum techniques, thus avoiding the complexity and expense of quantum cryptographic schemes. But now a new paper has uncovered a vulner