> That is already the case. If you whisper a secret into my ear, the government can subpoena me and force me to tell a court what you said. They can force you to tell a court what you said so long as it's not incriminating to you, and even then they can do it if they give you immunity.

This is true, but they can't compel me to inform on someone who had a whispered conversation near me that I couldn't hear. To me, the current bill is more like the latter scenario.

If I invented a communication device consisting of two cans and a connecting string, then sold it as a way for neighbor kids to talk privately to each other, they could not compel me to divulge the contents of their conversations because I wouldn't have access, even though I built the canmunicator. I think that in this case, what they're doing is more like mandating that I have a way to let them monitor all string vibrations.

If they want to subpoena information, they can demand that one of the parties actually involved in the communication surrender their keys. If they refuse, then it seems like basically the same situation as when both parties to a whispered conversation refuse to talk about it.