 impersonate Bob, which is the spirit of MIMA. Eve, a central office (CO) or point-of-presence (POP) network employee, may, indeed, figure out how to take over the public communication channel used by Alice and Bob to finalize their key exchange. Basically, the operation results in a key exchange K between Alice and Eve (and not Alice and Bob), all without Alice's and Bob's awareness. Eve may then impersonate Alice by proceeding to a key exchange K' with Bob, again without their awareness. Eve must also be able to intercept the encrypted messages, but this is an easier task, considering her CO or POP access prerogatives. Assuming that Eve has been successful in implementing such a complex arrangement altogether, she has become the "man in the middle" (so to speak). Consider, indeed, Eve's following course of action: Intercept Alice's encrypted message M, along with K as the secret key (that Alice thought she was sharing with Bob), call it EAlice(M), and perform decryption, i.e., generate M = Possibly change Alice's message M into some other message M' and perform re- encryption with Eve's new key K', i.e., generate Eve (M'); Perform key exchange with Bob, resulting in shared secret key K'; Send Bob the encrypted message ELve(M'). The above appears as a perfect MIMA of the reputedly "invulnerable" channel. No quantum-mechanical principles have been violated in the process, only the confidence that Alice and Bob are the only, exclusive, communicating parties. To achieve such a success in "breaking" the QKD channel and value chain, however, Eve must completely control both photon and public communication channels, to prevent them to "compare notes" and detect any anomaly. This would assume another level of verification protocol, which can, in turn, be attacked by malicious Eve. It is noteworthy to mention the giant-pulse attack (GPA). Alice's and Bob's transmitter and receiver photon-measurement terminals are obviously protected from any optical reflections in their shared link, a concept referred to as a return los