The case of locks on doors is not applicable to cryptography. While it is true that a lock can represent an encryption scheme, its not applicable here.
Reason is this:
What is reasonable suspecion here? What does the officer present to the judge as reason that he or she wants the warrant to search what is inside the lock? In a typical senario, the judge would have to be presented with evidence , such as "well judge, we smelled illegal substance in some place with a lock and we need to unlock it to see where the smell comes from", or "well judge we hear a woman's voice screaming in a house that is locked, and we need a warrant to get to the bottom of this". This is reasonable, that means that the lock is only a physical lock, and not a true lock in the sense that it locks the inside from the outside (including sound,thermal etcc..(closed system)).
In the case of a file that is encrypted, there is no way an officer can "reaonably suspect" that such encrypted file has important national security information for examlple. Because he has to present to the judge something real, something tangeable for the judge to issue the warrant.
Hence its not applicable here. Because an encrypted file is a totally closed system, that does not tell what its "locking" nor hints at it, where a reasonable expectation of privacy applies.
Hence, its not applicable.
Except that doesn't hold water. Consider the usual bete noir that is used when trying to make excuses to regulate the net; child p0rn and terrorism.
So the evidence presented would be "We know user X logged onto this child p0rn swapping web site at date X, time Y from their ISP logs", or "They are known to have swapped files with known pedophile Z" or "We know they attended terrorism training camps in country I" or "They purchased materials A, B and C used in bomb making". There's your scream evidence. It's not about assuming all encyrption hides criminality as you want to argue.
It most certainly IS applicable.
No it does not. In the case of logging into site X, what ever X is, that information is not hidden, and if a computer hard drive is searched and a given file Y is encrypted in the hard drive of the computer that was used to login to a site X with , does not really show that file Y that is encrypted is related to logging into X (it could be a totally unrelated file that was sitting in the harddrive and might have been created before loggin into site X). Logging (connecting to site X), is public information where there is no reasonable expectation of privacy (unless by agreements). Any network sniffer can be used to find that out at the LAN.
But I am talking about, a file, say an email, or a letter to your grandmother, or some kind of a legal document, that user X encrypt , how is the officer going to suspect that this encrypted file hold valuable national security information, or valuable evidence to a legal case as opposed to another file?
See in the analogy you presented with the lock in a door, the officers cannot just pick and choose to get a warrant because of attribute X of the house (say color, or size). Suppose you have a street where all the houses have locks, what distinguishes house A from B in getting a search warrant? I suspect that it would be that , for example, that there is a weird smell coming out from house B, and not from house A, and so the officers would get a warrant based on that. Leaving house A with its lock intact. This means that House A's reasonable expectation of privacy is not violated because the officers did not "DETECT", any reasonable evidence to use it to convince a judge that house A's expectation of privacy needs to be violated temporarily for the duration of an investigation.
Hence, the reason an officer gets a warrant is because they "DETECTED" information that was leaking from the lock system, and this information, by virtue of its leaking, has no reasonable expectation of privacy. Hence the officer can use that as evidence to gain more evidence by violating the lock of house A for instance.
With a cryptographically generated file , there is no way to sniff information about what is being encrypted (or locked), hence how is the officer going to convince a judge to issue a search warrant for the encrypted (locked) file content ?
See, that is why I say you cannot really enforce laws against technology. And that is as it should be, IMO.[A]
There are bad things out there, and I agree they should be combated, but a law should not be against good things. THere are good things in which encryption is used, like secure banking and other things.