The US National Security Agency has collected almost 200 million text messages a day from across the globe, using them to extract data including a person's location, contact networks and credit card details, according to top-secret documents.
The untargeted collection and storage of SMS messages - including their contacts - is revealed in a joint investigation between the Guardian and the UK's Channel 4 News based on material provided by former NSA contractor Edward Snowden.
The NSA program, codenamed Dishfire, collects "pretty much everything it can", according to UK spy agency GCHQ documents, rather than merely storing the communications of existing surveillance targets.
The NSA has made extensive use of its vast text message database to extract information on people's travel plans, contact books, financial transactions and more, including of individuals who are under no suspicion of illegal activity.
An agency presentation from 2011 - subtitled "SMS Text Messages: A Goldmine to Exploit" - reveals the program collected an average of 194 million text messages a day in April of that year. In addition to storing the messages themselves, a further program known as "Prefer" conducted automated analysis on the untargeted communications.
The Prefer program uses automated text messages such as missed call alerts or texts sent with international roaming charges to extract the information, which the agency has described as "content-derived metadata", and explains that "such gems are not in current metadata stores and would enhance current analytics".
On average, each day the NSA was able to extract:
- More than 5 million missed-call alerts, for use in contact-chaining analysis (working out someone's social network from whom they contact and when)
- Details of 1.6 million border crossings a day, from network roaming alerts
- More than 110,000 names, from electronic business cards, which also included the ability to extract and save images.
- Over 800,000 financial transactions, either through text-to-text payments or linking credit cards to phone users
The agency was also able to extract geolocation data from more than 76,000 text messages a day, including from "requests by people for route info" and "setting up meetings".
Other travel information was obtained from itinerary texts sent by travel companies, even including cancellations and delays to travel plans. Communications from US phone numbers, the documents suggest, were removed (or "minimized") from the database - but those of other countries were retained.
In a statement to the Guardian, an NSA spokeswoman said any implication that the collection was "arbitrary and unconstrained is false". The agency's capabilities were directed only against "valid foreign intelligence targets" and were subject to stringent legal safeguards, she said.