New top-secret NSA documents released by the Guardian UK newspaper reveal that the United States’ top spy agency can retain encrypted communications for as long as it takes analysts to decrypt the secret messages—even if they’re collected by chance and without a warrant.
In addition, the documents indicate that communication between people whose location is not known is considered communication between non-United States persons and can be retained. This puts users of Tor and other anonymity services in line to have their communication retained as well.
The two documents are from 2009 and both are signed by U.S. Attorney General Eric Holder and were submitted to the Foreign Intelligence Surveillance Court (FISA). Both provide step-by-step procedure on how the NSA is supposed to handle data and communication it gathers from non-U.S. persons pertaining to foreign intelligence matters, and what to do with data it inadvertently collects from U.S. citizens.
There are enough loopholes in the documents that allow for subjective calls to be made on whether data is to be analyzed and under what circumstances it’s to be discarded. Whistleblower Edward Snowden continues to insist that NSA analysts can view email and telephone conversations, but no proof has been levied that indicates this extends to encrypted communication and whether the NSA has broken Tor.
Tor is free software that anonymizes Web browsing sessions. It’s used by anyone wishing to keep their activities online private. That includes medical professionals exchanging health care records, or activists in oppressed areas of the world keeping their location private, as well as criminals. Most recently, a hacker trying to pull off a mass-scale page scrape of publicly viewable Facebook information triggered Facebook’s malware detection system which blocked Tor users from accessing the social network.
Tor developer Runa Sandvik told Threatpost yesterday that Tor gives users “location anonymity,” which would put its users on target for the NSA’s data collection activities. From one of the NSA documents: “A person known to be currently outside the United States, or whose location is unknown, wiil not be treated as a United States person unless such person can be positively identified as such, or the nature or circumstances of the person’s give rise to a reasonable belief that such person is a United States person.”
Tor uses encryption and a network of voluntary user machines that act as proxy for Web traffic. Once a user downloads the free Tor software, the client contacts a Tor directory server for a list of Tor nodes. It selects a path to forward traffic until it reaches its destination; traffic is encrypted along the way. Each stop on the path knows only the previous hop in the chain and where it’s forwarding the packets; no individual node knows the whole chain through which traffic is passed. Individual Tor paths last only 10 minutes.
The documents say that inadvertent communications must be destroyed within five years of acquisition and upon determination that no foreign intelligence information is contained. It stipulates, however, that electronic communication may be retained longer while under cryptanalysis.
“In the context of a cryptanalytic effort, maintenance of technical databases requires retention of all communications that are enciphered or reasonably believed to contain secret meaning, and sufficient duration may consist of any period of time during which encrypted material is subject to, or of use in, cryptanalysis,” the document said.