Which of the following statements are correct

The security of QKD protocols can be proven using the computational complexity assumptions.

In QKD it is possible to detect the presence of an eavesdropper by detecting a disturbance in the quantum state of the transmitted photons.

In optical fibers dephasing appears before depolarisation and therefore QKD systems based on phase encoding have generally much shorter operating ranges.

In QKD systems the secure key rate is proportional to the quantum bit error rate (QBER).