tion function. However, it is not clear how matching can be
accomplished in the transformed domain.
In the realm of template transformation, the so-called
biometric cryptosystems are gaining popularity (for a survey
on existing techniques, see ). These systems combine
biometrics and cryptography at a level that allows biometric
matching to effectively take place in the cryptographic do-
main, hence exploiting the associated higher security. For
example, Uludag et al.  convert ï¬ngerprint templates
(minutiae data) into point lists in 2D space, which implic-
itly hide a given secret (e.g., a 128-bit key). The list does
not reveal the template data, since it is augmented with chaff
points to increase security. The template data is identiï¬ed
only when matching minutiae data from an input ï¬ngerprint
is available. The system is observed to operate at a Gen-
uine Accept Rate (GAR) of 76% with no false accepts on a
database comprising of 229 users.
Although several techniques have been proposed to en-
hance the security of a userâs template, government regula-
tions will also have to be established in order to address the
issue of template privacy. For example, issues related to the
sharing of biometric templates across agencies (e.g., medical
companies and law-enforcement agencies) and the inferring
of personal information about an enrolled user from biomet-
ric data (e.g., âIs this person prone to diabetes?â) have to be
countered by establishing an appropriate legal framework.
4. SUMMARY AND CONCLUSIONS
We have discussed various types of attacks that can be
launched against a biometric system. We have speciï¬cally
highlighted techniques that can be used to elicit the con-
tents of a biometric template thereby compromising privi-
leged information. We discuss the importance of adopting
watermarking and steganography principles to enhance the
integrity of biometric templates. Cancelable biometrics may
be used to âresetâ the biometric template of a user in the
event that the userâs template is compromised. Also, bio-
metric cryptosystems can contribute to template security by
supporting biometric matching in secure cryptographic do-
Smart cards are gaining popularity as the medium for
storing biometric templates. As the amount of available
memory increases (e.g., state-of-the-art smart cards have 64-
KByte EEPROM), there is a propensity to store more infor-
mation in the template. This increases the risks associated
with template misuse. As a result, the issue of template secu-
rity and integrity continues to pose several challenges, and it
is necessary that further research be conducted in this direc-
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Appeared in the Proceedings of European Signal Processing Conference (EUSIPCO), (Antalya, Turkey), September 2005