New Research From Stanford: Computer Scientists Show Telephone Metadata Can Reveal Surprisingly Sensitive Personal Information

From Stanford University:

Most people might not give telephone metadata – the numbers you dial, the length of your calls – a second thought. Some government officials probably view it as similarly trivial, which is why this information can be obtained without a warrant.
But a new analysis by Stanford computer scientists shows that it is possible to identify a person’s private information – such as health details – from metadata alone. Additionally, following metadata “hops” from one person’s communications can involve thousands of other people.
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The researchers set out to fill knowledge gaps within the National Security Agency’s current phone metadata program, which has drawn conflicting assertions about its privacy impacts. The law currently treats call content and metadata separately and makes it easier for government agencies to obtain metadata, in part because it assumes that it shouldn’t be possible to infer specific sensitive details about people based on metadata alone.
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The computer scientists built a smartphone application that retrieved the previous call and text message metadata – the numbers, times and lengths of communications – from more than 800 volunteers’ smartphone logs. In total, participants provided records of more than 250,000 calls and 1.2 million texts. The researchers then used a combination of inexpensive automated and manual processes to illustrate both the extent of the reach – how many people would be involved in a scan of a single person – and the level of sensitive information that can be gleaned about each user.
From a small selection of the users, the Stanford researchers were able to infer, for instance, that a person who placed several calls to a cardiologist, a local drugstore and a cardiac arrhythmia monitoring device hotline likely suffers from cardiac arrhythmia. Another study participant likely owns an AR semiautomatic rifle, based on frequent calls to a local firearms dealer that prominently advertises AR semiautomatic rifles and to the customer support hotline of a major firearm manufacturer that produces these rifles.

Learn More: Read the Complete Article
The full text of the research article published in the Proceedings of the National Academy of Sciences is available here:
“Evaluating the privacy properties of telephone metadata”
Vol. 113, No. 20 (5536–5541)

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