Research Article Open Access

Quantum Key Distribution Using Decoy State Protocol

Sellami Ali1, Shuhairi Saharudin2 and M. R.B. Wahiddin2
  • 1 International Islamic University Malaysia, Malaysia
  • 2 Information Security Cluster, Malaysia


Problem statement: Quantum key distribution provides unconditional security guaranteed by the fundamental laws of quantum physics. Unfortunately, for real-life experimental set-ups, which mainly based on faint laser pulses, the occasional production of multi-photons and channel loss make it possible for sophisticated eavesdroppers to launch various subtle eavesdropping attacks including the Photon Number Splitting (PNS) attack. The decoy state protocols recently proposed to beat PNS attack and to improve dramatically distance and secure key generation rate of Quantum Key Distribution (QKD). Approach: Objective of this study was experimental implementation of weak decoy + vacuum states QKD for increasing the performance of QKD system. To show conceptually how simple it was to apply the weak decoy + vacuum state idea to a commercial QKD system, we chosen ID-3000 commercial quantum key distribution system manufactured by id quantique. To implement the weak decoy + vacuum state protocol, we had to add some new optical and electronics components to id quantique and to attenuate each signal to the intensity of either signal state or weak decoy or vacuum state randomly. Results: In our implementation, the attenuation will be done by placing a VOA (variable optical attenuator) in Alice’s side. Specifically, our QKD system required the polarizations of 2 pulses from the same signal to be orthogonal. Therefore the VOA must be polarization independent so as to attenuate the two pulses equally. The VOA utilized in experiment to attenuate signals dynamically was Intensity Modulator (IM). We had implemented weak + vacuum protocol on a modified commercial QKD system over a 25 km of telecom fibers with an unconditionally secure key rate of 6.2931×10-4 per pulse. Conclusion: By making simple modifications to a commercial quantum key distribution system, we could achieve much better performance with substantially higher key generation rate and longer distance than QKD system without decoy state.

American Journal of Engineering and Applied Sciences
Volume 2 No. 4, 2009, 694-698


Submitted On: 19 November 2008 Published On: 31 December 2009

How to Cite: Ali, S., Saharudin, S. & Wahiddin, M. R. (2009). Quantum Key Distribution Using Decoy State Protocol. American Journal of Engineering and Applied Sciences, 2(4), 694-698.

  • 4 Citations



  • Quantum cryptography
  • quantum key distribution
  • decoy state protocol and optical communications