Passports, like any physical ID, can be altered and forged. That's partly why for the last 11 years the United States has put RFID chips in the back panel of its passports, creating so-called e-Passports. The chip stores your passport information—like name, date of birth, passport number, your photo, and even a biometric identifier—for quick, machine-readable border checks. And while e-Passports also store a cryptographic signature to prevent tampering or forgeries, it turns out that despite having over a decade to do so, US Customs and Border Protection hasn't deployed the software needed to actually verify it.

This means that since as far back as 2006, a skilled hacker could alter the data on an e-Passport chip—like the name, photo, or expiration date—without fear that signature verification would alert a border agent to the changes. That could theoretically be enough to slip into countries that allow all-electronic border checks, or even to get past a border patrol agent into the US.

"The idea of these things is that they’re supposed to provide some additional electronic security over a standard passport, which can be forged using traditional techniques," says Matthew Green, a cryptographer at Johns Hopkins University. "The digital signature would provide that guarantee. But if it’s not checked it doesn’t."

A letter to CBP on Thursday from senators Ron Wyden of Oregon and Claire McCaskill of Missouri highlights this crucial shortcoming. More than 100 countries now offer passports that come with a digital chip, and fewer than half of those include the capability to verify the integrity of data using a digital signature. But Wyden and McCaskill stress that while the US demands that countries in the Visa Waiver program put a chip in their passports, it has failed to fully realize its own e-Passport program.

"CBP does not have the software necessary to authenticate the information stored on the e-Passport chips," the two Senators wrote. "Specifically, CBP cannot verify the digital signatures stored on the e-Passport, which means that CBP is unable to determine if the data stored on the smart chips has been tampered with or forged."

The situation appears particularly shameful given that the US led the promotion of e-Passports around the world. "I had assumed that they would verify this," says Martijn Grooten, a security researcher for the information and testing platform Virus Bulletin. "It may cause some grumbles among countries in the Visa Waiver program: The US has demanded they offer e-Passports, and then only implemented the system partially themselves. It is a bit embarrassing."

'I had assumed that they would verify this.' Martijn Grooten, Virus Bulletin

Even worse, DHS and CBP have known about the problem for at least eight years; the Government Accountability Office issued a report in 2010 detailing the need to implement signature verification for e-Passports. "DHS does not have the capability to fully verify the digital signatures because it ... has not implemented the system functionality necessary to perform the verification." GAO concluded at the time. "The additional security against forgery and counterfeiting that could be provided by the inclusion of computer chips on e-passports issued by the United States and foreign countries ... is not fully realized."

Nearly a decade later, the DHS Inspector General's list of ongoing projects requiring oversight still doesn't include rolling out the software for signature verification. A CBP spokesperson said in a statement to WIRED that, "While CBP does not verify the country certificate of an e-Passport at this time, CBP does verify the data contained within the chip and in the machine-readable zone (MRZ). The data on the chip and the MRZ is compared and any inconsistencies are immediately flagged for the CBP officer," meaning that digital kiosks that scan passports during entry into the US compare the identifying data on the chip with the information on the biographical page of the passport. "The chip is also verified to ensure it has not been modified or tampered with."