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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.
You're assuming that the suspect is a computer geek. 95% of the people don't even know what a hash is (in the computer sense). This is a good automated way of searching. However, if they run into someone who is a computer expert, the authorities will probably face decrypting volumes.