Phone Metadata Reveals A Lot of Personal Data

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.

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.

Researchers found that a large number of people could get caught up in a single surveillance sweep. When the National Security Agency examines metadata associated with a suspect’s phone, it is allowed to examine a “two-hop” net around the suspect. Suspect A calls person B is one hop; person B calls person C is the second hop. Analysts can then comb the metadata of anyone within two hops of the suspect. By extrapolating participant data, the researchers estimated that the NSA’s current authorities could allow for surveilling roughly 25,000 individuals – and possibly more – starting from just one “seed” phone user.



Credits:
https://news.stanford.edu/2016/05/16/stanford-computer-scientists-show-telephone-metadata-can-reveal-surprisingly-sensitive-personal-information/