In 2005, the United States began testing biometric electronic passports (e-passports). The new passports contain embedded computer chips that hold the same information that is written in regular passports, in addition to a unique digital signature designed to protect the data from tampering or unauthorized access. Two more features were added to later issues, including a digital antenna embedded in the passport cover that will allow remote reading devices to capture the stored chip data. The State Department received several thousand comments that were overwhelmingly opposed to the new passport, primarily based on fears that terrorists with remote readers could identify and target them as U.S. citizens. Additionally, 27 countries resisted the technology, citing privacy concerns.