Decius wrote:

Does encrypting Internet communications create a reasonable expectation of privacy in their contents, triggering Fourth Amendment protection? At first blush, it seems that the answer must be yes: A reasonable person would surely expect that encrypted communications will remain private. In this paper, Professor Kerr explains why this intuitive answer is entirely wrong: Encrypting communications cannot create a reasonable expectation of privacy. The reason is that the Fourth Amendment regulates access, not understanding: no matter how unlikely it is that the government will successfully decrypt ciphertext, the Fourth Amendment offers no protection if it succeeds. As a result, the government does not need a search warrant to decrypt encrypted communications.

If you put an encrypted file in a password protected stuffit file, would that give the file fourth ammenment protection from the access needed to open the stuffit file and actual protection from the encryption? If you are handed a warrant demanding "access" to some file, you should not be required to surrender your encrypted key as well because "understanding" is not required by law, right? Somehow I think that the analogy doesn't hold water. Because "understanding" requires forging an algorithmic key to break apart an encrypted framework, I think that access is required for understanding. If you wrote a message on a piece of paper and folded it in on itself and sealed it with glue, this would qualify as an envelope. Encryption mathmatically "folds" communication and seals it with a key. There is no closer digitaly secure envelope analogy one can make. If one were to contend that digital communications should be a valid and useful method to communicate, the envelope is needed to assure viability for most important uses. If you can't count on encryption for this, what can you count on?

terratogen wrote:
If you put an encypted file in a password protected stuffit file, would that give the file fourth ammenment protection from the access needed to open the stuffit file and actual protection from the encryption?

Why would stuffit creat an expectation of privacy where encryption doesn't? I think that it would be couched as "understanding" just as encryption is, under this theory.

If you are handed a warrant demanding "access" to some file, you should not be required to surrender your encrypted key as well because "understanding" is not required by law, right?

I think you would unless you claimed a 5th amendment right. They would imprison you for refusing to disclose the key. Think Judith Miller.

Somehow I think that the analogy doesn't hold water.

There is a huge gap missing in the analysis, and that is the 4th amendment protection for communications in transit. This same lawyer has argued that the 4th doesn't apply to internet communications in transit because internet communications aren't naturally enveloped. One might argue in that context that encrypting them would envelope them. However, there is a statute which requires a warrant to obtain electronic communications in transit, so that statue is, in that context, 4th amendment equivelent and so it doesn't matter anyway.

Having said that, what is the scenario in which you want the 4th amendment to apply where it does not already apply? They need one to search your house. They need one to intercept your email. Where are you worried they'll get access to the cyphertext without a warrant and you'd expect the 4th amendment to protect you in the event that they happen to know how to decrypt it without the key?