GCHQ spied on millions of Yahoo video chats, harvested sexual images of chatters, compared itself to "Tom Cruise in Minority Report"

A stunning new Snowden leak reveals that the UK spy agency GCHQ harvested images and text from millions of Yahoo video chats, including chats in which one or both of the participants was British or American. Between 3 and 11 percent of the chats they intercepted were sexual in nature, and revealing images of thousands of people were captured and displayed to spies. The programme, called OPTIC NERVE, focused on people whose usernames were similar to those of suspects, and ran from at least 2008 until at least 2010. The leak reveals that GCHQ intended to expand the programme to Xbox 360 Kinect cameras and "fairly normal webcam traffic." The programme was part of a facial recognition research effort that GCHQ compared to "Tom Cruise in Minority Report." While the documents do not detail efforts as widescale as those against Yahoo users, one presentation discusses with interest the potential and capabilities of the Xbox 360's Kinect camera, saying it generated "fairly normal webcam traffic" and was being evaluated as part of a wider program. Beyond webcams and consoles, GCHQ and the NSA looked at building more detailed and accurate facial recognition tools, such as iris recognition cameras – "think Tom Cruise in Minority Report", one presentation noted.

Sexually explicit webcam material proved to be a particular problem for GCHQ, as one document delicately put it: "Unfortunately … it would appear that a surprising number of people use webcam conversations to show intimate parts of their body to the other person. Also, the fact that the Yahoo software allows more than one person to view a webcam stream without necessarily sending a reciprocal stream means that it appears sometimes to be used for broadcasting pornography."

The document estimates that between 3% and 11% of the Yahoo webcam imagery harvested by GCHQ contains "undesirable nudity". Discussing efforts to make the interface "safer to use", it noted that current "naïve" pornography detectors assessed the amount of flesh in any given shot, and so attracted lots of false positives by incorrectly tagging shots of people's faces as pornography.

UK spy agency intercepted webcam images of millions of Yahoo users [Spencer Ackerman and James Ball/The Guardian]