You just need one person to leak it (or 2-3, if you care about journalistic integrity and receive the information from multiple sources). Remember, you don't need true cryptography -- you just need to get information out. It's okay to violate kerckhoff's principle and have a scheme that's dependent on the algorithm itself so that the government can't automatically decrypt your data. Like using obscure steganography. You might be discovered later, but once the information is out, it's out.
It's also what makes things like "Secret societies", and massive conspiracies to be so damned hard to maintain. Information in a high level area wants to equalize to lower levels.
