I have a friend who has a lock PIN on his phone of 0000.
What does that mean? Well, for a start, it means he does not really care too much about the data on the phone being used by someone else, but it means more than that.
It is about boundaries.
He has in fact "locked' his phone. Someone trying to get in, even if they know or guess 0000, is breaking through that lock.
I think morally, and possibly even legally, "breaking in" is massively different to being let in. The lock says that you are "not authorised", so things like Computer Misuse Act kick in if you go passed that point.
If someone wanders in to your house through an open door, it is not the same as someone using a very simple lock pick to get passed a really poor quality lock and opening your front door.
I started wondering if this had wider implications. E.g. if someone like Apple have a backup of your data, including a backup of your private keys used by iMessage and the like, protected by a relatively low entropy key like a 4 digit PIN for example, what happens if asked for that data. Well, they can honestly say they do not have the data as it is encrypted. I am not sure if existing laws allow authorities to request that they "hack" what they have (e.g. trying all 10,000 four digit PINs). Expecting a company to hack in to their customer's data would be a heck of a step legally and morally, but having a good reason not to disclose it because of the protection may be enough?
We can only hope that laws do maintain some concept of boundaries in the future - not just in the real world, where it matters if you invite a bailiff in to your house or he forces his way past you, and the same in the computer world where it matters if you break passed a 0000 PIN or do not try to.