Externalized Fingerprint Matching

The 9/11 tragedy triggered an increased interest in biometric passports. According to several sources [2], the electronic ID market is expected to increase by more than 50% per annum over the three coming years, excluding China. To cost-effectively address this foreseen explosion, a very inexpensive memory card (phonecard-like card) capable of performing fingerprint matching is paramount. This paper presents such a solution. The proposed protocol is based on the following idea: the card stores the user’s fingerprint information to which random minutiae were added at enrolment time (we denote this scrambled template by t). The card also stores a binary string w encoding which of the minutiae in t actually belong to the holder. When an identification session starts, the terminal reads t from the card and, based upon the incoming scanner data, determines which of the minutiae in t are genuine. The terminal forms a candidate w′ and sends it to the card. All the card needs to do is test that the Hamming weight of w⊕w′ is smaller than a security threshold d. It follows that the card only needs to embark passive data storage capabilities, one exclusive-or gate, a shift register, a counter and a comparator (less than 40 logical gates).