I'm doing a tiny bit of research and am wondering if there are any methods currently known for securing a sender such that it can be conclusively determined that a file has not been tampered with after it was created. I don't work in cryptography and only have a passing knowledge of the topics but I'm well aware of the hashing algorithms. My question is more about verifying that someone hasn't attacked and manipulated the system that performs the hash. We trust the hash that is provided to us but how can we verify the provider of the hash wasn't corrupted?
For example, assume a device takes a photo or video and automatically hashes (and possibly digitally signs?) the image or video produced, so that a recipient can hash the received image and verify the hash matches the one produced by the device. Consider a scenario where someone records an image with this device but wants to provide a falsified image after the fact. Is it possible to prevent them from doing so? i.e. do we have a method to prove that person A tampered with the image and/or the device after the fact, and that the image absolutely should no longer be trusted?