Here's the story. Every Oyster card has a radio-frequency identification chip that communicates with readers mounted on the ticket barrier. That chip, the "Mifare Classic" chip, is used in hundreds of other transport systems as well — Boston, Los Angeles, Brisbane, Oslo, Amsterdam, Taipei, Shanghai, Rio de Janeiro — and as an access pass in thousands of companies, schools, hospitals, and government buildings around Britain and the rest of the world.

The security of Mifare Classic is terrible. This is not an exaggeration; it's kindergarten cryptography. Anyone with any security experience would be embarrassed to put his name to the design. NXP attempted to deal with this embarrassment by keeping the design secret.

The group that broke Mifare Classic is from Radboud University Nijmegen in the Netherlands. They demonstrated the attack by riding the Underground for free, and by breaking into a building. Their two papers (one is already online) will be published at two conferences this autumn.

The second paper is the one that NXP sued over. They called disclosure of the attack "irresponsible," warned that it will cause "immense damages," and claimed that it "will jeopardize the security of assets protected with systems incorporating the Mifare IC." The Dutch court would have none of it: "Damage to NXP is not the result of the publication of the article but of the production and sale of a chip that appears to have shortcomings."

Exactly right. More generally, the notion that secrecy supports security is inherently flawed. Whenever you see an organization claiming that design secrecy is necessary for security — in ID cards, in voting machines, in airport security — it invariably means that its security is lousy and it has no choice but to hide it. Any competent cryptographer would have designed Mifare's security with an open and public design.

Secrecy is fragile. Mifare's security was based on the belief that no one would discover how it worked; that's why NXP had to muzzle the Dutch researchers. But that's just wrong. Reverse-engineering isn't hard. Other researchers had already exposed Mifare's lousy security. A Chinese company even sells a compatible chip. Is there any doubt that the bad guys already know about this, or will soon enough?

Publication of this attack might be expensive for NXP and its customers, but it's good for security overall. Companies will only design security as good as their customers know to ask for. NXP's security was so bad because customers didn't know how to evaluate security: either they don't know what questions to ask, or didn't know enough to distrust the marketing answers they were given. This court ruling encourages companies to build security properly rather than relying on shoddy design and secrecy, and discourages them from promising security based on their ability to threaten researchers.

It's unclear how this break will affect Transport for London. Cloning takes only a few seconds, and the thief only has to brush up against someone carrying a legitimate Oyster card. But it requires an RFID reader and a small piece of software which, while feasible for a techie, are too complicated for the average fare dodger. The police are likely to quickly arrest anyone who tries to sell cloned cards on any scale. TfL promises to turn off any cloned cards within 24 hours, but that will hurt the innocent victim who had his card cloned more than the thief.

The vulnerability is far more serious to the companies that use Mifare Classic as an access pass. It would be very interesting to know how NXP presented the system's security to them.

And while these attacks only pertain to the Mifare Classic chip, it makes me suspicious of the entire product line. NXP sells a more secure chip and has another on the way, but given the number of basic cryptography mistakes NXP made with Mifare Classic, one has to wonder whether the "more secure" versions will be sufficiently so.

This essay originally appeared in the Guardian.

Azulstar soon answered several RFPs and partnered up with major firms to bring Wi-Fi to Rio Rancho, N.M., Winston-Salem, N.C., Sacramento, Calif., and most notably Silicon Valley--a set of dozens of cities along with county government and private enterprise all wanting some kind of tiered Wi-Fi across 1,500 sq mi.

While EarthLink, MetroFi, and even Kite Networks (with their extensive Arizona buildout in Tempe launched a bit before any other large competiting network) seized the headlines, and later made news about their stalls, failures, and exits, Azulstar seemed quietly to sink into the sand. The Wireless Silicon Valley deal fell apart, as did Sacramento after efforts to get stakeholder and outside investment seemed to fail to materialize, and the marquee partners--Cisco, IBM, and Intel--just wouldn't step up to the plate to make the project move forward. Azulstar was the lead techology firm, but the money just didn't come. (Both California projects are moving forward with a different set of partners and expectations now.)

Rio Rancho was perhaps one of the biggest letdowns. City manager Jim Payne explained in an interview a few weeks ago, "They had a number of things that were going against them from the start, and they did make an attempt to meet the requirements of the contract." But Rio Rancho voted to not just terminate the contract after years of attempts to make the network work, but rejected a proposal from Azulstar a few weeks ago to switch over equipment on the poles. Azulstar now has to remove all its devices.

All of this might make the typical company head a bit depressed about his firm's future, and less than sanguine about the potential for wireless broadband to work at all. Not so for Tyler van Houwelingen, Azulstar's chief, and I have to admit that he convinced me that the wireless provider has a fighting chance, due to a good combination of timing, spectrum policy, and a large dollop of can-do spirit.

The reporter notes other common threads of problems with metro-scale networks: lowballed budgets, which turned out to underestimate infrastructure costs (nodes, real-estate rights, utility pole issues), low demand, and weak signals inside homes. Tempe apparently had 1,000 subscribers at one point, in a city of 166,000 (2005 census estimate).

The articles states, "The upside is Tempe and other Valley cities didn't spend taxpayer dollars." Of course, as I've noted before, the idea with a wireless network should be to both conserve expenses and reduce them. "Taxpayer dollars" is a shibboleth of those who believe government can solve no ills. Those who believe that are typically also fine with government overspending by paying large companies as private contractors rather than working in a public/private partnership that reduces expenses and yet puts most dollars into the private sector--just in smaller firms.

Gilbert, Ariz., one of several Arizona cities that was contracted with Kite, reaches fifth stage of mourning, acceptance: Gobility, Kite's ostensibly current owner, hasn't communicated with the city in two months, and its elusive head wouldn't comment for this article in local paper. The city isn't too depressed.

Oklahoma City is OK with lack of Wi-Fi network for public access: They're pretty pleased with their large mesh network for emergency services.