In this opinion piece, a cybersecurity researcher argues that loopholes in a new data retention bill push those wanting to use the 'Net anonymously into cafes, libraries, and fast food restaurants. The following op-ed does not necessarily represent the opinions of Ars Technica.

On Tuesday, the Republican-controlled House Judiciary Committee will hold a hearing in support of mandatory data retention legislation. The bill that they have proposed requires that Internet Service Providers, such as Comcast and Time Warner, save records of the IP addresses they assign to their customers for a period of 18 months.

Data retention is a controversial topic and loudly opposed by the privacy community. To counter such criticism, the bill's authors have cunningly (and shamelessly) named it the Protecting Children from Internet Pornographers Act of 2011. This of course means that anyone who opposes data retention must go on record as opposing measures to catch sexual predators.

As a thought experiment, let us give the bill's authors the benefit of the doubt. Let us assume, for a moment, that this additional data is not sought as part of the war on filesharing, but is in fact necessary to catch those who commit one of the most horrible, indefensible crimes. With this in mind, let's ask the question: will this bill be effective at catching sexual predators?

The wireless loophole

The bill includes a curious exception to the retention requirements: it doesn't apply to wireless data providers, such as AT&T and Verizon, or operators of public WiFi networks, such as Starbucks and McDonalds.

When questioned about this, a Republican committee staffer told CNET in May that the wireless loophole was added because wireless networks are designed in such a way that IP addresses are assigned to multiple users or accounts and they are "not technologically capable of retaining the type of data that law enforcement needs because that's not how their system works."

This explanation is completely bogus. Wireless providers, like wireline broadband providers, are quite capable of retaining logs of the IP addresses they temporarily issue to their customers. Many wireless providers, such as Sprint and Verizon, already retain IP logs for at least a year.

The true explanation for the loophole is, I believe, that the wireless carriers have powerful and remarkably effective lobbyists.

McDonalds: last refuge for the anonymous

If this legislation passes with the wireless loophole intact, residential broadband providers will be forced to retain identifying records that can be used to link users' online activities to their authenticated identities. Mobile phone carriers will continue to retain data voluntarily, and public WiFi networks will remain one of the last places where people, whether angels or devils, can browse the Internet anonymously.

If the House Judiciary Committee is truly concerned about protecting children, why is it proposing legislation that will encourage sexual predators to visit McDonalds restaurants in order to share their illicit contraband online? These are, after all, restaurants packed with innocent children, who have convinced their parents to take them there in search of a Happy Meal.

Of course, McDonalds aren't the only places with free, public, anonymous WiFi access. There are also public libraries, schools, and parks.

Christopher Soghoian is a Graduate Fellow at the Center for Applied Cybersecurity Research at Indiana University.