Isn't this basically achieved by standard cloud storage on phones? Photos and videos get uploaded automatically (with authentication for the user account) and presumably that action is logged somewhere the user can't edit. Just need to prove those logs are secure, and there you go.
Unless you’re they police in a murder case, you’re probably not going to get google or apple to give you something that certifies that a file was uploaded before a specific time and not modified after. And just showing me the modification date in the UI wouldn’t convince me.
Much easier with the account holder's consent, it's probably in the "data download" thing you can request. And probably available by subpoena. It's like phone records.
I don't mean "date modified" in the file metadata when it's uploaded (of course that could easily be spoofed before upload) but the actual "date uploaded". You know something must have been made before a certain time.
