A Proof of the Security of Quantum Key Distribution
  We prove the security of theoretical quantum key distribution against the most general attacks which can be performed on the channel, by an eavesdropper who has unlimited computation abilities, and the full power allowed by the rules of classical and quantum physics. A key created that way can then be used to transmit secure messages such that their security is also unaffected in the future. 
Eli Biham, Michel Boyer, P. Oscar Boykin, Tal Mor and Vwani   Roychowdhury