> A good example is iMessage's use of device keys for parties of a conversation, without the use of a central key that lives on Apple's servers. They cannot be

> A good example is iMessage's use of device keys for parties of a conversation, without the use of a central key that lives on Apple's servers. They cannot be compelled to turn over the master key, and no one can steal the key either. I'm not intimately familiar with the security of iMessage, but Apple controls the key server, as far as I understand. Can't law enforcement just compel Apple to make their key server respond with a public key owned by the NSA, instead of the public key of whichever device wants to receive the secret information?