[peterwwillis]

They used to legislate crypto, so there's no reason they couldn't now. Back in the day, creating (and "exporting") an SSL library without a license was illegal.

If you're talking TLS, whomever holds the private key would have to use it to decrypt either stored or transmitted data and turn that data over to the feds. If you're talking PGP or something, then either the makers of PGP would have to put in a backdoor, or stop making it.

To implement this all the government would need is to send an NSL to anyone who creates, owns or operates any tool with encryption technology, or anyone who operates a network or service that encryption is going over.