4 ms·

Apologies as I misread "quantum" as "quantum-resistant" above. However, I would still contest that quantum key exchange is "simpler". I mean, you need a quantum

Apologies as I misread "quantum" as "quantum-resistant" above. However, I would still contest that quantum key exchange is "simpler". I mean, you need a quantum channel and to accurately exchange qubits without disturbance. Not to mention a small initial secret. It doesn't really work too well with our current infrastructure.

OscarCunningham 9y ago
Agree with most of your points. But I suspect building a quantum infrastructure will be easier (and therefore occur earlier) than building quantum computers. >Not to mention a small initial secret This is interesting, what are you referring to here?
- mannykannot 9y ago
  Encryption has become pervasive in modern communication, yet it is clear that we still need more to properly protect the things we are doing. Does the quantum infrastructure that you are proposing not imply an almost complete replacement of the current global communications network with quantum channels, or at least to shadow it with a co-extensive one for key distribution? Is that close to being feasible for mobile and other radio-connected devices?
- PeterisP 9y ago
  Doesn't quantum transmission infrastructure require direct connections from A to B? I.e. you could use it for a single uninterrupted fiber cable, or for the channel between your antenna and a satellite, but not with our common fiber infrastructure that relies on repeaters / re-transmitters. As soon as there's any device between you and the recipient that breaks the entanglement, all the guarantees of quantum encryption go out of the window, and it's possible to attack the comms at that retransmission point.
  - OscarCunningham 9y ago
    >Doesn't quantum transmission infrastructure require direct connections from A to B? No, the retransmitters can preserve the entanglement (and A and B can verify that this has been done). In fact (providing qubits can be stored) the transmission can be done indirectly and in advance. The telecom company produces lots of entangled qubits and gives a bunch to each customer, keeping half of each pair for itself. Then when Alice wants to communicate securely with Bob they ask the telecom company to take the corresponding qubits and perform a joint measurement. This entangles Alice's qubits with Bob's (like making a connection at a telephone exchange). Then Alice and Bob can measure their qubits (in various bases) to create a one-time-pad. The clever thing is that Alice and Bob can (by checking that on a portion of the qubits their results always matched when they used the same basis) verify that they did indeed have maximally entangled qubits and therefore no one was listening-in.

OscarCunningham 9y ago

Agree with most of your points. But I suspect building a quantum infrastructure will be easier (and therefore occur earlier) than building quantum computers. >Not to mention a small initial secret This is interesting, what are you referring to here?

mannykannot 9y ago
Encryption has become pervasive in modern communication, yet it is clear that we still need more to properly protect the things we are doing. Does the quantum infrastructure that you are proposing not imply an almost complete replacement of the current global communications network with quantum channels, or at least to shadow it with a co-extensive one for key distribution? Is that close to being feasible for mobile and other radio-connected devices?
PeterisP 9y ago
Doesn't quantum transmission infrastructure require direct connections from A to B? I.e. you could use it for a single uninterrupted fiber cable, or for the channel between your antenna and a satellite, but not with our common fiber infrastructure that relies on repeaters / re-transmitters. As soon as there's any device between you and the recipient that breaks the entanglement, all the guarantees of quantum encryption go out of the window, and it's possible to attack the comms at that retransmission point.
- OscarCunningham 9y ago
  >Doesn't quantum transmission infrastructure require direct connections from A to B? No, the retransmitters can preserve the entanglement (and A and B can verify that this has been done). In fact (providing qubits can be stored) the transmission can be done indirectly and in advance. The telecom company produces lots of entangled qubits and gives a bunch to each customer, keeping half of each pair for itself. Then when Alice wants to communicate securely with Bob they ask the telecom company to take the corresponding qubits and perform a joint measurement. This entangles Alice's qubits with Bob's (like making a connection at a telephone exchange). Then Alice and Bob can measure their qubits (in various bases) to create a one-time-pad. The clever thing is that Alice and Bob can (by checking that on a portion of the qubits their results always matched when they used the same basis) verify that they did indeed have maximally entangled qubits and therefore no one was listening-in.