Geraldo A. Barbosa

Geraldo A. Barbosa

A secure key distribution protocol protected by light's noise was introduced in 2003 [Phys. Rev. A 68, 052307 (2003)]. That protocol utilized the shot noise of light present in the optical channel (eg., an optical fiber) to restrict information leaks to an adversary. An initial shared information between the legitimate users allowed them to extract more information from the channel than the one obtained by the adversary. That original paper recognized the need for a privacy amplification step but no specific protocol was presented. More recently that original idea was improved with a specific privacy amplification protocol [arXiv:1406.1543v2 [cs.CR] 8 Jul 2015] while keeping the use of an optical communication channel. This work merges main ideas of the protection given by the light's noise in a protocol applied to wireless channels. The use of a wireless channels together with recorded physical noise was introduced from 2005 to 2007 (see eg, arXiv:quant-ph/0510011 v2 16 Nov 2005 and arXiv:0705.2243v2 [quant-ph] 17 May 2007). This work improves those embrionary ideas of wireless channels secured by recorded optical noise. The need for specific optical channels is eliminated with the wireless variation and opens up the possibility to apply the technique to mobile devices. This work introduces this new scheme and calculates the associated security level.

Geraldo A. Barbosa, Jeroen van de Graaf

One-time-pad (OTP) encryption simply cannot be cracked, even by a quantum computer. The need of sharing in a secure way supplies of symmetric random keys turned the method almost obsolete as a standing-alone method for fast and large volume telecommunication. Basically, this secure sharing of keys and their renewal, once exhausted, had to be done through couriers, in a slow and costly process. This paper presents a solution for this problem providing a fast and unlimited renewal of secure keys: An untappable key distribution system is presented and detailed. This fast key distribution system utilizes two layers of confidentially protection: 1) Physical noise intrinsic to the optical channel that turn the coded signals into stealth signals and 2) Privacy amplification using a bit pool of refreshed entropy run after run, to eliminate any residual information. The resulting level of security is rigorously calculated and demonstrates that the level of information an eavesdropper could obtain is completely negligible. The random bit sequences, fast and securely distributed, can be used to encrypt text, data or voice.