Privacy security

Welcome to the machine—Yahoo mail scanning exposes another US spy tool

At its most basic level, this newly surfaced tool exposes another US digital surveillance program. It differs from so-called "upstream" spying in which the authorities tap directly into the Internet backbone and scan for certain search terms—a spying program with diminishing returns as more and more data on the Internet has become encrypted. This Yahoo situation is also different from the Prism program, where the authorities acquire customer data from tech companies matching chosen search selectors.

In this latest bit of spying to come to light, it still hasn't been revealed whether the Yahoo e-mail scanning was of e-mail metadata—like the headers—or of a message's content. Many, including NSA whistleblower Edward Snowden, believe content was being scanned. And if it was content, that would make the latest program perhaps even more aggressive than the US bulk collection of telephone metadata Snowden exposed.