India's Elephantine Effort
Marina Krakovsky
Communications of the ACM
The full implementation, though, is fraught with problems, most of which stem from the project's sheer size, given India's population of 1.2 billion. "Biometric systems have never operated on such a massive scale," says Arun Ross, an associate professor of computer science at West Virginia University.
One of the biggest challenges is deduplication. When a new user tries to enroll, the system must check for duplicates by comparing the new user's data against all the other records in the UID database. Hundreds of millions of records make this a computationally demanding process, made all the more so by the size of each record, which includes up to 12 higher-resolution images.
The demands continue each time there's an authentication request. "The matching is extremely computationally intensive," says Prabhakar. At peak times, the system must process tens of millions of requests per hour while responding in real time, requiring massive data centers the likes of Google's.
Achieving acceptable levels of accuracy at this scale is another major difficulty. Unlike passwords, biometrics never produce an exact match, so matching always entails the chance of false accepts and false rejects, but as the number of enrollments rises, so do the error rates, since it becomes more likely that two different individuals will share similar biometrics. Using a combination of biometrics—instead of a single thumbprint, for example—greatly improves accuracy and deters impostors. (In the words of Marios Savvides, assistant research professor in the department of electrical and computer engineering at Carnegie Mellon University, "It's hard to spoof fingerprints, face, and iris all at the same time.") But using multiple biometrics requires extra equipment, demands information fusion, and adds to the data processing load.
Other steps to improve accuracy also bring their own challenges. "The key issue," says Nalini Ratha, a researcher at the IBM Watson Research Center, "is have I captured enough variation so I don't reject you, and at the same time I don't match against everybody else?" Capturing the optimal amount of variation requires consistent conditions across devices in different settings—no easy feat in a country whose environment varies from deserts to tropics and from urban slums to far-flung rural areas. "It's almost like having many different countries in a single country, biometrically speaking," says Ross.
The challenge isn't just to reduce errors—under some conditions, a biometric reader may not work at all. "If it's too hot, people sweat and you end up with sweaty fingers," says Prabhakar, "and if it's too dry, the finger is too dry to make good contact with the optical surface of the scanner." Normalizing across varied lighting conditions is essential, since all of the biometric data is optical.
Security Challenges
As if these problems weren't enough, the UID system poses formidable security challenges beyond the threat of spoofing. "People get carried away by one type of attack—a fake finger, a fake mask, or something," says IBM's Ratha, "but there are probably 10 other attacks to a biometric system that can compromise the system."
For starters, when data is stored in a centralized database, it becomes an attractive target for hackers. Another vulnerability is the project's reliance on a network of public and private "registrars"—such as banks, telecoms, and government agencies—to collect biometric data and issue UIDs. Though registrars might ease enrollment, they're not necessarily worthy of the government's trust. Banks, for example, have been helping wealthy depositors evade taxes by opening fictitious accounts, so entrusting the banks with biometric devices doesn't make sense, says Sunil Abraham, executive director of the Centre for Internet and Society in Bangalore. "If I'm a bank manager, I can hack into the biometric device and introduce a variation in the fingerprint because the device is in my bank and the biometric is, once it's in the computer, just an image sent up the pipe," he says. Though careful monitoring could catch such hacks, Abraham says that's not realistic once you've got as many records as Aadhaar will have.
Registrars may also make UIDs, which are officially voluntary, a de facto requirement for services, especially in the current absence of a law governing how the data can be used. Such "function creep" troubles privacy advocates like Malavika Jayaram, a partner in the Bangalore-based law firm Jayaram & Jayaram, who says, "If every utility and every service I want is denied to me without a UID card, how is it voluntary?" The loss of civil liberties is too high a price to pay for a system that she believes leaves gaping opportunities for continued corruption. "The guy handing out the bags of rice could ask for a bribe even to operate the machine that scans the fingerprints, or he could say that the machine isn't working," says Jayaram. "And there's every chance the machine isn't working. Or he could say, 'I don't know who you are and I don't care; just pay me 500 rupees and I'll give you a bag of rice.' All the ways that humans can subvert the system are not helped by this scheme."
Abraham suggests a more effective way to root out fraud through biometrics would be to target the much smaller number of residents who own most of the country's wealth, much of it illgotten. "The leakage is not happening at the bottom of the pyramid," he says. "It's bureaucrats and vendors and politicians throughout the chain that are corrupt."
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