Could this be accomplished at the storage level instead of at the camera level? Could an SD card have an onboard encryption engine? We have cards with built-in wifi already.
Also, while some enterprising card supplier is at it, they might as well implement a TrueCrypt-style hidden volume solution. That, methinks, would be most useful (for a very, very small subset of their customer base).
After all, as has been pointed out already - chances are the people who can inspect your camera would also have ways(tm) to make you come up with the password.
Back when Microsoft rolled out Windows Mobile 7, they made use of this automatically. This caught many a new user off guard, and hilariously the only devices that could non-destructively unlock said cards were Nokia Symbian phones.
https://en.wikipedia.org/wiki/Secure_Digital#Card_password
I don't know what degree of protection that gives you.
Looks like SecureMMC supports actual encryption, not just password protection.
IIRC FileVault stores a "forgot my disk" password with iCloud, which is likely subject to subpoena. That assumes there's no law enforcement/nation-state investigative service backdoor in FileVault. The built-in, OS level disk encryption is likely insufficient, so why use a Mac at all here?
You could just offboard the footage to a machine running a Free version of Linux running LUKS and then after shooting and in a secure location and manner give the files to somebody to do the video editing on the Mac.
The disk encryption is actually quite adequate on a Mac.
We also have no evidence of any backdoors in the encryption in Apple products, and quite a bit of recent evidence that there are no such backdoors.
They had all already stopped relying on any closed system to keep their communications secure. They were all using Tails to communicate through Tor without leaving a minimal unencrypted footprint. At the point where you are relying on Tor to communicate and are explicitly using Tails to keep your communication secret then why would you start relying on a Macbook, running a proprietary OS, with non-open crypto, to hold your secrets if you're already scared the neo-Stazi are going to break down the door and steal your unlocked, decrypted Linux machine that you have all of the trust in the world in? For that reason alone you would skip the Mac.
I thought the days of wandering around with a camera while having a recorder on a shoulder strap were left behind in the eighties.
Then high quality, professional shots are hidden while the kind of photos you might take as a tourist are sitting there openly.
It'd be detectable if you knew what to look for, but a) you likely can use more subtle activation techniqies (photo knocking?) and b) a lot of security checks aren't that sophisticated.