[csandreasen]

I don't think that's an appropriate analogy. You may as well just say "In the 1700s, if you wrote an enciphered letter..." since cryptography isn't a new concept. Various schemes have been used to protect military and diplomatic communications for centuries. If you did so then or now, you wouldn't be under any obligation to reveal the contents, but you take on the additional burden of actually performing all of the necessary calculations, securely destroying the scratch paper you used in the process of encrypting the message, handling key management and distribution, securing the areas where the encrypting/decrypting is taking place (you wouldn't want the redcoats barging in the hour or so while you're in the middle of converting the plaintext to ciphertext), etc.

Nobody does that anymore. You're instead using a tool that someone else made, and either that tool or the other person is handling all of the hard work. Tools definitely can be regulated - I need a license to drive; I need to register my car; I need to go through a background check to own a gun; I can own a gun, but if I misuse it I go to jail; felons can't purchase guns legally; I can't buy a nuclear weapon or the fissile material needed to make own.

The questions that policymakers are fumbling through right now are things like "how (if at all) do we regulate tools and the companies that make/distribute them if those tools allow people evade law enforcement?"