Comment by kelp | Hacker News Reader

Comment by kelp | Hacker News Reader

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I keep meaning to write up a longer form version of this idea that I've been kicking around to solve this.

This issue is often talked about as an unsolvable problem, but I feel like we already have the technology to deal with it.

Lots of devices, such as an iPhone already have a secure enclave that can be used for identity. Why not use this to sign videos and images for authentication purposes?

Then certain devices can produce verified, undoctored images and videos. Or even allow some amount of limited tweaking, and editing while attesting to the original.

This could be embedded into the file produced, like exif data, and read by services like Facebook and Twitter to badge the image/video as verified and undoctored. This could improve the amature case significantly.

Professional photography and video equipment could have similar capabilities so originals could be produced and proven to be genuine.

I guess this idea still depends on the hardware devices remaining secure, which is far from trivial, but it does increase the cost of producing a fake. And to keep producing really good fakes, you have to have a zero day to fake a genuine signature, or it becomes know that any media produced with that device version is suspect.

If such a system became widly adopted, at the very least, savvy users, and the media would be suspect of anything not signed. And perhaps the general public would also learn to be skeptical, particularly if the issue of fakes became more widespread.

Haha I was also thinking about using an HSM module to sign videos [1]. I think the problem is that anyone can just record a projector screen and replay audio through some speakers, and then Facebook and Twitter will still badge the video as verified and undoctored. You could detect this by analyzing the video and audio, but then it's just an arms race with machine learning.

[1] https://news.ycombinator.com/item?id=18074425

If you really want to produce propaganda, it's possible and plausible to build optics that will project arbitrary pixels directly onto the sensor of a phone camera. It's expensive and tricky, but it's a one-off expense and small compared to known intelligence projects. The phone can be secure, unmodified, but still be "convinced" of a false reality.

Furthermore, who controls the keys? The device manufacturers definitely will have access to them (since the signing keys need to be put in the device), and it's not that you need to convince the world that it came from my phone (where you might need to extract a secret from it), you need to convince that the key came from a phone. Once the major governments get a bunch of fake keys that would have/could have been put in a real phone of a major manufacturer, you either admit the inability to discriminate propaganda or you have to automatically distrust all media produced from all phones of that manufacturer, which won't happen, the public will look at such media and believe it or not depending on whether it matches their opinion, not depending on its signature.

I think it remains unsolvable: you cannot plug the analog hole. Hardware device can be as secure as you like, but you can record your fake output to sign it and it suddenly becomes very genuine, I don't think it bumps the cost sufficiently.

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