US District Court Says Calculating a Hash Value = Search

bfwebster writes "Orin Kerr over at The Volokh Conspiracy (a great legal blog, BTW) reports on a US District Court ruling issued just last week which finds that doing hash calculations on a hard drive is a form of search and thus subject to 4th Amendment limitations. In this particular case, the US District Court suppressed evidence of child pornography on a hard drive because proper warrants were not obtained before imaging the hard drive and calculating MD5 hash values for the individual files on the drive, some of which ended up matching known MD5 hash values for known child pornography image and video files. More details at Kerr's posting." Update: 10/28 16:23 GMT by T : Headline updated to reflect that this is a Federal District Court located in Pennsylvania, rather than a court of the Commonwealth itself.

Comments

Bad way to search for kiddie porn

[betterunixthanunix]

This sounds like the worse possible way to search for kiddie porn, because a suspect who wanted to conceal his activities could just change a single pixel, and the entire hash would change. They would need a signature method that doesn't change dramatically when a single bit changes, like something based on a frequency analysis.

I dont see how the 4th amendment applies here

[Phizzle]

The guy whose computer was searched, abandoned the computer and gave up any rights at that point, the person who found the porn was computers new owner. Just like any trash tossed out becomes public domain, there should have been zero expectation of privacy at that point. I am not a legal scholar, but I do not see how the 4th amendment applies here. It would be no different than if this was a diary in a different language and the person who inherited the diary found a translator, upon finding criminal evidence it would be fully admissible.