I've thought about this a little bit - I guess the security of the system depends on what you consider to be the channel, source, and destination. The argument

I've thought about this a little bit - I guess the security of the system depends on what you consider to be the channel, source, and destination. The argument is that |device|-------->network--------->|device| may be secure, but that doesn't mean |human|-->|device|-------->network--------->|device|-->|human| is secure!