There are several different approaches to quantum key distribution, but they can be divided into two main categories depending on which property they exploit.

Of course, this merely moved the issue back a level, to that of security of key distribution.

One could hope that there might be a way to exploit the intrinsic properties of quantum mechanics, as in the protocols for unconditionally secure key distribution.

The LoTW system emphasizes secure authentication using cryptographic key distribution.

Depending on the method of key distribution employed, a paper tape reader KOI-18 may also be required.

What sets these tasks apart from key distribution is that they aim to solve problems between two parties, Alice and Bob, who do not trust each other.

For more info see: key distribution in wireless sensor networks.

A long key takes longer to convey (securely) to the parties who need it, and so mistakes are more likely in key distribution.

Fourth generation systems (1990s) use more commercial packaging and electronic key distribution.

In cryptography, this is often a problem with key distribution, and gave rise to public key cryptography.