Kam Wai Clifford Chan

Multi-photon quantum key distribution based on double-lock encryption

We present a quantum key distribution protocol based on the double-lock cryptography. It exploits the asymmetry in the detection strategies between the legitimate users and the eavesdropper. With coherent states, the mean photon number can be as larger as 10.

Multi-stage quantum secure communication using polarization hopping

This paper proposes a generalized multi-stage multi-photon protocol that uses arbitrary polarization states to securely communicate between a sender and a receiver. Because the polarization measurement of an arbitrarily polarized state results in altering the state in an irreversible way, any such measurement produces noise in the measured state. The proposed multi-stage protocol exploits this phenomenon to provide quantum secure communication. This paper assesses the vulnerability of the multi-stage protocol to photon number splitting attack and Trojan horse attack. In addition, it presents an upper bound on the number of photons that can be used per pulse to exchange information while maintaining quantum-level security. Determination of such a bound is important for the multi-stage protocol to operate in the multi-photon domain while maintaining a quantum level of security. Furthermore, this paper proposes a key/message expansion scheme that provides another layer of security to the multi-stage protocol. The multi-stage protocol, can potentially provide higher data rates as well as longer communication distances. Copyright

Automatic cardiac cycle determination directly from EEG-fMRI data by multi-scale peak detection method

BACKGROUND In simultaneous EEG-fMRI, identification of the period of cardioballistic artifact (BCG) in EEG is required for the artifact removal. Recording the electrocardiogram (ECG) waveform during fMRI is difficult, often causing inaccurate period detection. NEW METHOD Since the waveform of the BCG extracted by independent component analysis (ICA) is relatively invariable compared to the ECG waveform, we propose a multiple-scale peak-detection algorithm to determine the BCG cycle directly from the EEG data. The algorithm first extracts the high contrast BCG component from the EEG data by ICA. The BCG cycle is then estimated by band-pass filtering the component around the fundamental frequency identified from its energy spectral density, and the peak of BCG artifact occurrence is selected from each of the estimated cycle. RESULTS The algorithm is shown to achieve a high accuracy on a large EEG-fMRI dataset. It is also adaptive to various heart rates without the needs of adjusting the threshold parameters. The cycle detection remains accurate with the scan duration reduced to half a minute. Additionally, the algorithm gives a figure of merit to evaluate the reliability of the detection accuracy. COMPARISON WITH EXISTING METHOD The algorithm is shown to give a higher detection accuracy than the commonly used cycle detection algorithm fmrib_qrsdetect implemented in EEGLAB. CONCLUSIONS The achieved high cycle detection accuracy of our algorithm without using the ECG waveforms makes possible to create and automate pipelines for processing large EEG-fMRI datasets, and virtually eliminates the need for ECG recordings for BCG artifact removal.

An Ultra-Secure Router-to-Router Key Exchange System

This chapter presents an ultra-secure router-to-router key exchange system. The key exchange process can be initiated by either router at will and can be carried out as often as required. The cryptographic strength of the proposed protocols lies in the use of multi-stage transmission where the number of variables exceeds the number of stages by one, ensuring that the number of possible measurements is one less that the number of variables. The proposed system carries out all processing in electronics and is not vulnerable to the man in the middle attack. The treatment presented in this chapter is based on the authors’ work in [1, 2].

Preliminary Security Analysis of the Multi-stage Protocol

This chapter presents a security analysis of the multi-stage protocol assessing its vulnerability to known security attacks. It shows that the multi-stage protocol can offer quantum level security under certain conditions. The material presented in this chapter is based on the authors’ work previously published in [12, 13].

The Three-Stage Protocol: Its Operation and Implementation

This chapter introduces the three-stage multi-photon protocol, its operation and implementation in a laboratory environment. The implementation uses free-space optics as the transmission medium. Parts of this chapter are based on the authors’ work previously reported in [1].

The Multi-stage Protocol

This chapter generalizes the three-stage protocol into a family of multi-stage protocols. It compares the multi-stage protocol with single-photon protocols and illustrates how a multi-photon protocol can be made secure against man-in-the-middle attack. Since a multi-photon protocol is, in general, subject to photon-siphoning attacks, the protocol introduces another variable to thwart such attacks. Parts of this chapter are based on the authors’ work previously reported in [1, 2, 3].

Application of the Multi-stage Protocol in IEEE 802.11i

This chapter extends the application space of the multi-stage multi-photon protocol to wireless communication. In particular, it examines the viability of using the multi-stage multi-photon protocol for secure key distribution in the IEEE 802.11i protocol.

Intrusion Detection on Optical Fibers

This chapter discusses an application of the polarization property of light in detecting intrusion on an optical fiber with the objective of stealing information flowing through it. Detection of intrusion, if timely accomplished, will offer an effective means to prevent information from being captured by a malicious agent. The material presented in this chapter is based on the authors’ work previously published in [1].

Security Analysis of the Multi-stage Protocol

This chapter analyzes intercept-and-resend and photon number splitting attacks in the multi-stage multi-photon protocol. It lays down the conditions under which the multi-stage multi-photon protocol can approach the strength of a quantum-secure protocol. The material presented in this chapter is based on the authors’ work previously published in [16].