"Wink wink" has been long dealt with in law. If it's a device that is useless without the key, it'd wind up as a distinction without a difference if Apple really chased this down rather than hiring the devs. "Substantial non-infringing use" is the bar to clear in patent terms.
Except, streaming music you own to a computer you own is legal regardless of whether or not some piece of propietary software you use has a private key that you aren't supposed to know. The key is out. Using it for anything is legal.
Uh, I'm not so sure about that. The DMCA makes circumventing a copyright protection measure illegal unless you fall into one of the very narrow exemptions.
How is this circumventing a copyright protection measure?
This is like opening the hood of a car that requires a key that the manufacturer will only give to authorized dealers. If you figure out how to open the hood, the government is not going to stop you from messing around with the stuff in your car. It's yours, after all.
Here's what's happening here. Apple wants you to buy Apple hardware, so they cripple iTunes such that it will only speak with devices that know a secret password. Now, with the secret out, it will talk to any device.
This has absolutely nothing to do with copyright infringement.
This is like opening the hood of a car that requires a key that the manufacturer will only give to authorized dealers.
Yes, that's exactly what it's like. Indeed, auto manufacturers have already been abusing the DMCA to prevent independent repair shops from accessing computer diagnostic codes.
"(c) Other Rights, Etc., Not Affected. — (1) Nothing in this section shall affect rights, remedies, limitations, or defenses to copyright infringement, including fair use, under this title."
IANAL, but that would not protect you from the DMCA provisions that make it a crime to distribute tools designed for breaking DRM, even if you intend such tools to be used for fair use purposes.
Then you should probably ship a small device that a general computer, and there just happens to be some firmware / software floating around on the internet for it.