> No but if you treat the "key exchange" process as a one time pad key, it doesn't matter that the actual ciphertext can be intercepted, since it's impossible t

> No but if you treat the "key exchange" process as a one time pad key, it doesn't matter that the actual ciphertext can be intercepted, since it's impossible to decrypt it. Sure, I'm not saying you can't achieve information theoretic security. My point here is that discussion of quantum key exchange should use precision in terminology - integrity and confidentiality are meaningfully different. If the ciphertext from a quantum channel is extracted (in whatever way), it is not more secure than a ciphertext in which the keys were shared in person and promptly destroyed via Cold War-era means. You won't be aware of an adversary trying to break the encryption once they have it in their possession, and the ciphertext won't "break" if plied with an incorrect key (though it would be secure for other reasons). Rather, you'd know if the key exchange process is being broken, or if information was not transmitted correctly.