I think this is quite interesting.
An Australian man who set up an elaborate network of hidden cameras to spy on his flatmates has escaped jail time after police were unable to crack the encryption scheme protecting his computer.
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But the files were encrypted, and the 39-year-old Wyllie refused to divulge the password. The inability of police to review the files – combined with the fact that a camera he used was unplugged when the raid was commenced – meant prosecutors lacked the hard evidence they needed to prove the man had secretly taped his flatmates.
I’m under the impression that RIPA could be used over here to compel a suspect to give up the password, but it’s quite hard to find information on when Part 3 of the Act has been used, so perhaps I’m mistaken.