Comment by mixologic | Hacker News Reader

Comment by mixologic | Hacker News Reader

This is a database of call detail records (http://en.wikipedia.org/wiki/Call_detail_record) and the numbers they have called, and numbers that have called them. It does not contain subscriber data (names, account information) - just metadata about calls.

They use this database to find cycled phone numbers that have similar calling patterns. (Phone number 1 tends to make and receive calls from number 2, 4, 9 and 13. in geographic area X) Phone number 1 stops making calls, and phone number 50 starts making/receiving calls to 2, 4, 9, and 13 in area Y. So they can assume that whomever owns 50 is the same person that used to own 1 and now they're in area Y.

Maybe Im just being clueless today, but can anybody explain to me what is so chilling about this system? I don't see where it can really be abused unless you've got some stalker that works for LA's DEA and they're trying to find out their estranged ex-wife's new phone number?

When you have the entire call graph, it's almost trivial to match it up to names. And then you know who everyone calls and who calls them, which I would argue is almost as fundamental an affront to privacy as knowing the actual content.

Law enforcement doesn't have the entire call graph. They have a service, that they can request specific data from, that takes 2-5 days to return the requested information, which is pretty much only "additional phones, and switched phones", and they have to have a subpoena to get that data in the first place. This isnt some google search they can mine for whatever. The 2-5 day lag is almost certainly paperwork bureaucracy verifying that they have a legal reason to search the database.

I suppose the folks at the "Hemisphere Regional Data Center" could theoretically match up the names to the phone numbers (not AT ALL trivial - I used to work with credit header data and telco record data - the data quality is an absolute shitshow), but that power certainly is not in the hands of any local law enforcement.

"DO NOT mention Hemisphere in any official reports or court documents"

It perverts the justice system when the police and prosecutors hide their investigation methods.

Subscriber data is easily matched, as mentioned in the slides. It advises law enforcement officers and other judicial officials to perjure themselves. There have been enough discussions about the value of metadata for identifying people that one should have an opinion by now as to whether it is a violation of one's rights for the gov't to collect it indiscriminately.

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