> A side issue is that being able to prove authenticity would be valuable, as the issue of faked news/images becomes more visible in the eyes of the general public. Having some sort of GPG signing of (image + gps time + gps position) would be valuable, although establishing the trust chain in practice would be quite difficult and requires some serious thought.

I've thought a bit about this recently, and was excited by this news because it seemed like an opportunity to talk about it.

So, here goes.

The obstacle that is most obvious I think, is, "what if someone gets the private key out of the camera, and uses that to sign doctored images?". This is a serious problem, and I don't think it is one that can be solved by software alone. It needs a hardware solution.

The solution I propose for this, is using the technology used in the ORWL computer https://www.orwl.org/wiki/index.php?title=Main_Page .

The ORWL computer has an open source design, and it stores the data on it encrypted, with (as far as I can tell. I am not a security expert.) quite good physical security. It keeps a key stored on a region of the machine where it will be quickly deleted if tampering is detected. It has a security system which is separate from the rest of it, so that the OS being run does not need to worry about the encryption things at all.

It has sensors to detect a variety of different possible methods of intrusion, such as breaking through a barrier, sudden pressure changes, sudden temperature changes, etc. each of which will cause the decryption key to be quickly deleted. You can check the details on the wiki.

My idea is to, instead of the key that is stored in this part of memory being used to decrypt and encrypt the data on the hard drive of the ORWL pc, it would store the private key used to sign the images (or video) being recorded by the camera.

If anyone tried to get at the private key, the private key would be deleted. But the images already signed could still be verified with the public key.

Two other problems are, how do people know that a given public key corresponds to a camera with a secure system like this? What if someone just generates a keypair and claims that the public key is for one of these cameras? How can people trust that these cameras work as advertised?

For the confirming that the cameras work as advertised, the solution for this can be inherited from the ORWL pc. Although the ORWL pc is designed to delete the key upon any physical intrusion, it is also designed to be easy to take apart to inspect, and is (almost entirely?) open source. Opening it up to inspect it will of course cause the key to be deleted, but once one puts it back together again, a new key can be generated using a built in hardware Random Number Generator. This solution could, I believe, also work for this proposed camera design. I believe this is a satisfactory solution.

For the "why should I believe that this public key corresponds to a private key from a properly working camera of this kind?" question, the solution is similar, I think.

My idea is to use either a tree or web of trust sort of thing. The idea is that an organization could certify such a public key by opening up the camera, performing tests to confirm that it conforms to the specifications, close it back up, and generate the new keypair. This whole process would be recorded by cameras (or a camera) of the same kind. In this way, it could be confirmed that, given that a certain public key corresponds to a secure camera like this, that other public keys were produced by and correspond to other secure cameras like this.

If there is an exploit in this system, it should not be harder to demonstrate the flaw than to exploit the flaw, because, if one was able to get a public key verified by this system, which did not in fact belong to such a camera, then one could use it to sign something other than an image, and demonstrate the flaw.

I would appreciate any feedback on this idea.

If you read it, thank you for taking the time to read it.

edit:

apparently, some cameras have had image signing features before, but have not had the physical security to protect the private key, as described in this thread : https://news.ycombinator.com/item?id=13178138 . I did not know this.