Journal of Information Security, 2010, 1, 23-28 doi:10.4236/jis.2010.11003 Published Online July 2010 (http://www.SciRP.org/journal/jis) Copyright © 2010 SciRes. JIS Eliminating Forgers Based on Intra Trial Variability in Online Signature Verification Using Handglove and Photometric Signals Andrews Samraj 1 , Shohel Sayeed 1 , Loo Chu Kiong 1 , Nikos E. Mastorokis 2 1 Faculty of Information Science and Technology, Multimedia University, Malacca, Malaysia 2 Faculty of Engineering, Industrial Engineering Department, Technical University of Sofia, Sofia, Bulgaria E-mail: andrews.samraj@mmu.edu.my Received March 5, 2010; revised June 9, 2010; accepted July 15, 2010 Abstract The novel reinforcement to the data glove based dynamic signature verification system, using the Photomet- ric measurement values collected simultaneously from photo plethysmography (PPG) during the signing process is the emerging technology. Skilled forgers try to attempt the genuine signatures in many numbers of trials. The wide gap in the Euclidian distances between forgers and the genuine template features prohibits them from successful forging. This has been proved by our repeated experiments on various subjects using the above combinational features. In addition the intra trial features captured during the forge attempts also differs widely in the case of forgers and are not consistent that of a genuine signature. This is caused by the pulse characteristics and degree of bilateral hand dimensional similarity, and the degrees of pulse delay. Since this economical and simple optical-based technology is offering an improved biometric security, it is essential to look for other reinforcements such the variability factor considerations which we proved of worth considering. Keywords: Photo Plethysmography, Data Glove, Signature Verification, Multimodal Biometrics 1. Introduction Enhancements to the signature verification systems has been suggested by many researchers [1-3] and bio signal based security features are also considered as a unique alternatives for applications that require some document evidence like signing cheques and security documents. The signal based biometrics in the only applicable means for people with physical disability [4]. Making use of multimodal biometric technology which provides unique and robust identification features for every individual is in great demand in security environ- ments that require high quality authentication methods. Using PPG wave forms to distinguish individuals using their biometric component was suggested by researchers in 2007 [5] and is employed in protected applications like e-transactions and access control mechanisms. As a fortification to the current signal based dynamic signature verification system, we have used a new me- thod by using the combination of the plethysmographic component along with the data glove signals to make the authentication process more robust and distinctive. The possibility of skilled forging is reduced by the PPG feature that brings in the hand and heart dimensions of an individual into the signature feature vector. In order to further reinforce the effectiveness of the system here in this research work we have considered the intra trial variation approach to further validate the signature proc- ess. This method assures the elimination of skilled forg- ing by a multi level authentication. 2. The Equipment The plethysmographic system, a simple equipment that functions on the intensity of light reflected from the skin’s surface. The red cells count below the skin is con- sidered to determine the volume of blood in the particu- lar area. The recorded signal posses the measurement of changes in venous blood volume and the arterial blood pulsation in the arterioles, hence representing the heart rate. There are two values supplied by the system and are the measurements of transmission and reflectance. A sam-