Analysis of attack and technical issues
When we first described this algorithm, the assumption was that Eve had the same computational power as Bob and Alice and could spy on the conversations between them. So, if Eve has a quantum computer in her hands and all the instruments to detect the photons’ polarization, could she break the algorithm?
Let’s see what Eve can do with her incommensurable computational power and the possibility of eavesdropping on the classical and quantum channels.
It looks like she is in the same situation as Bob (receiving photons). When Alice transmits the photons to Bob, even if the transmission comes through a quantum channel, if someone can capture the entire sequence of bits before Bob’s selection, it’s supposed that they will be able to collect the bits of the key. This could be true if Eve gets 100% of the measurements correct, but that is unthinkable for a key with a 1,000-bit length or more.
Moreover, the...