The issue will be once someone breaks the secure enclave in the CCD, all of the video they produce will now be trustworthy. CCDs are pretty lightweight in general as most of the heavy lifting is meant to be offloaded to the ISP—so the on-die processing for the CCD is generally very lightweight and wouldn’t have buffers large enough to sign each frame. Also there is no standardized way of creating a secured MIPI connection. You can do some clever things to mitigate for this, but it is far from what I’ll call “best practice” and more along the lines of a bespoke solution.