Fake Hands: Spoofing Hand Geometry Systems Hong Chen 1 , Hamed Valizadegan 1 , Carrie Jackson 2 , Shannon Soltysiak 2 and Anil K. Jain 1 1 Department of Computer Science and Engineering 2 Forensic Science Program, Department of Criminal Justice Michigan State University East Lansing, Michigan 48824 chenhon2@cse.msu.edu, valizade@cse.msu.edu, jacks735@msu.edu, soltysi3@msu.edu, jain@cse.msu.edu Hand geometry systems are widely used for attendance monitoring, access control and identity verification [1-3]. Features extracted from a presented hand shape are matched against stored genuine templates for the purpose of verification. Due to the inherent similarity of hand shapes, the hand geometry systems are not appropriate for identification and unattended high-security applications. While the idea of making fake hands to spoof hand geometry systems has been proposed [4, 5], to our knowledge, it has not been implemented in practice. In this paper, we present two simple approaches for making fake hands. Using these fake hands, we were successful in attacking a HandKey II system, produced by Recognition Systems®. The first approach utilizes plaster for making fake hands [6]. The material used includes molding alginate, casting plaster and a peg board, on which the pegs are laid out in exactly the same fashion as in the HandKey II system. The first step is to make a molding container, which has the peg board as its bottom surface (Fig. 1(a)). After fixing the pose of a real hand according to the pegs, a mixture of alginate and water is poured into the container (Fig. 1 (b)). The solidification process takes 2 to 7 minutes, and the real hand can then be pulled out of the alginate mold without breaking it (Fig. 1 (c)). The next step is to fill the mold with mixer of plaster powder and water. Depending on the ratio of the plaster and water, it takes from 30 minutes to 24 hours for the plaster to solidify (Fig. 1 (d)). Fig. 1(e) shows how a fake hand is presented to the HandKey II system and how it gets verified by the system. (a) (b) (c) (d) (e) Figure 1. Making a plaster fake hand. (a) Place the hand in the correct posture; (b) fill in molding material; (c) solidified mold; (d) a plaster hand; (e) a plaster hand is presented to the hand geometry system.