Analysis of Information Leakage in Quantum Key Agreement

Quantum key agreement is one of the approaches to unconditional security. Since 1980＇s, different protocols for quantum key agreement have been proposed and analyzed. A new quantum key agreement protocol was presented in 2004, and a detailed analysis to the protocol was given. The possible game played between legitimate users and the enemy was described： sitting in the middle, an adversary can play a ＂man-in-the-middle＂ attack to cheat the sender and receiver. The information leaked to the adversary is essential to the length of the final quantum secret key. It was shown how to determine the amount of information leaked to the enemy and the amount of uncertainty between the legitimate sender and receiver.