Perhaps I am a bit late in getting to this issue, but it warrants some more highlighting.
Last month the New York Times reported that Federal law enforcement and national security officials want legislation to require all services that enable encrypted communications to be able to comply if served with a wiretap order. In other words, the government wants the ability to intercept and unscramble encrypted messages.
I understand the law enforcement and national security needs here. And if the legislation applies only to messages encrypted by service providers as part of the service – like Blackberry messages – then the Fourth amendment concerns of this action are probably minimal. The bigger issues, it seems, will be technical and expense issues for the providers. I will leave that to the techies.
The real challenge will be if/when the federal government seeks the authority to unscramble messages encrypted by users. I will post later my thoughts on whether the Fifth Amendment protects against providing the password to encrypted files. But at a minimum, when a user takes affirmative steps to encrypt a message or document, and then stores that message or document on the web, a warrant based on probable cause should be necessary for the government to obtain access. By encrypting the message, the user is indicating a subjective expectation of privacy. And I believe that society is willing to recognize that expectation of privacy as reasonable in those circumstances. (Yes, for the lawyers, I am using a basic Katz analysis here).