
throughout a person’s lifetime, and thus cannot be
revoked once compromised (unlike changing a pass-
word, PIN, or even one’s name). This immunity from
falsification and revocation makes biometrics a good
choice as an universal identifier. For example, banks,
government agencies, and supermarkets may use the
thumb print for verification. The convenience of using
a single fingerprint to access one’s bank account, to
obtain government services, and to pay for groceries is
extremely compelling for end-users and organizations
alike. But so are the risks correspondingly magnified.
The linking of the bank’s database with those of the
government and the supermarket to monitor one’s
intimate details would, in most places, be considered
an egregious invasion of privacy. Even if such moni-
toring were sanctioned by the appropriate authority,
the victim is unlikely to derive much comfort.
Privacy is not the same as security. Privacy is
concerned with people (their intimate details, personal
space), whereas security has to do with systems. A good
privacy policy protects people, whereas a secure system
is one that is effective at preventing unauthorized
access to the resource being protected. Identity theft
(the use of someone else’s identity for personal gain) is
primarily a security breach, but also a privacy viola-
tion. Thus, privacy begins with securing the biometric
system itself. An insecure biometric system affords
little privacy protection.
Effectively addressing the privacy issues arising from
the deployment of biometric systems require a holistic
and multipronged approach. This chapter highlights
five ways, as described in the following sections.
System Issues
Privacy should not be an afterthought; rather, mea-
sures to safeguard privac y should be designed into
a biometric system right from the beginning. Good
strategies for doing this may be found in [6, 7].
In additi on, [8] has two chapters on the privacy aspects
of biometrics in relation to U.S. and European laws.
The following highlights the main issues.
1. Alternative technologies. Consider nonbiometric alter-
natives. Biometrics is not the only technology for
verifying identity or controlling access to a protected
resourc e. Other technologies may be more appropri-
ate, and less privacy invasiv e. For instance, the humble
lock-and-key works very well for gymnasium lockers,
and replaci ng it with a fingerprint access control
system seems excessive . Besides the obvious privacy
concerns, the fingerprint system does not permit the
ad hoc transfer of authorization, as when asking a
friend to retrieve one’ s belongings from the locker.
The low-tech lock-and-key has no such problem.
2. Choice of biometrics. Choose a biometric appropri-
ate for the applica tion, taking into account cultural
and religious sensitivities. As mentioned before,
DNA and retina scans may be regarded as invading
one’s bod ily privacy because of the way these sam-
ples are collected. Since DNA can reveal genetic
defects and retina scans can reveal diabetes, their
usage can lead to function creep (also see below).
Likewise, avoid choosing biometrics that requires
physical contact for acquisition w hen doing so
would alarm end-users who consider such contact
unhygienic. Finally, using face recognition may
offend the modesty and privacy of end-users who
veil their faces for religious reasons.
3. Template storage. To enhance privacy, templates
must be securely stored, preferably with a strong
encryption method. Moreover, distributed storage
is preferred over a centralized database. Where
possible, delete the template as soon as it is no
longer required. This is preferable to storing it
indefinitely. Finally, allowing the end-user to decide
when and how the template can be used reduces
privacy risks. This could be achieved by permitting
the end-user to opt in or out (of using the biomet-
ric system) at the end-user’s discretion, or to speci-
fy the encryption method, or the duration and
location of template storage. In this regard, the
▶ Match-on-Card technology for fingerprint veri-
fication, in which all the steps in the biometrics
architecture are implemented on the smart card
itself, comes closest to fulfilling this privacy ideal.
4. Function creep. Once a biometric system is opera-
tional, it is often convenient to use it for other
purposes. From a privacy perspective, this must be
resisted, even if the secondary purpose is a noble
one. At the very least, consent must be obtained
from the end-user for the expanded scope of bio-
metric usage. This is especially true for biometrics
that reveals more than just identity, e.g., DNA and
retina scans that reveal medical conditions, finger
vein patterns that reveal blood oxygen level, and
face images that reveal gender, ethnicity, and
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Privacy Issues