Yes, but you can usefully protect point-to-point communications using Diffie-Hellman or similar. You can't if you know someone is decrypting in the middle, even

Yes, but you can usefully protect point-to-point communications using Diffie-Hellman or similar. You can't if you know someone is decrypting in the middle, even if they are using a common symmetric key that can be recovered by subpoena or NSL.