Despite the fact that this same "serious flaw" exists with classical cryptography devices, only worse (since the quantum attack doesn't reveal plaintext A until

Despite the fact that this same "serious flaw" exists with classical cryptography devices, only worse (since the quantum attack doesn't reveal plaintext A until B is sent). How would you do this with classical cryptography? Isn't the point about this particular flaw that it is pretty much undetectable (other than inspecting the hardware itself (which is outside the scope of the article that treats it as a black box)). If the same were to be implemented on classical cryptography it would be comparatively trivial to detect if someone tried to sneak in an old message interleaved with a new message (you know the plaintext + key and thus you know exactly what that will generate). The compelling argument for quantum cryptography is that it is provably secure (well, that's the theory) and it is quite difficult to prove that the hardware has not been tampered with. The thing you could do with classical cryptography is to in some way "leak" the key (such as what debian inadvertently did with openssl) but the whole point of quantum cryptography is to have a perfect key distribution to combat any known or unknown attacks. I found the abstract, http://arxiv.org/abs/1201.4407 http://arxiv.org/abs/1201.4407 , shorter and more informative than the article.