a timestamp can't prove anything. What stops somebody else from copying your content, but timestamping it earlier and submitting it as proof? How can google verify it?
In fact, google may have an incentive to allow this - since those scammy sites may actually be using google ads, while legit sites may have their own ad-nework which google may not be part of...
You'd need some sort of negative affirmation as well. "when I published this article, searching for it yielded nothing" signed by a trusted party would be a stronger statement. But no clue how you actually do that.
Something like this can only work if all news publishers always publish the article hash and those that don't will simply not get crawled and not be valid as proof in DMCA takedowns.
What makes the bitcoin blockchain good for this? The bitcoin blockchain is good for posting transactions within the bitcoin network and kind of a shitty solution for "a generic blockchain"
Why a blockchain at all? Why not just a merkle tree? Surely there is somewhere better than the bitcoin blockchain for this. CT logging isn't done on the bitcoin blockchain for a reason.
So sure, you can prove that something wasn't created after the date of the transaction (assuming you're using a CS hashing function), but for this to work in this specific context, you'd need every publisher to be posting transactions to this log.
If I post an article and post a hash to $genericBlockchainWhichIsReallyJustAMerkleTree, what prevents someone from copying, backdating, and saying that I copied them? That they didn't post to the log as well?
Is a CT log a blockchain? Because really what we're talking about here is a signed ledger which may be decentralized but very well may be centralized as well.
I can use it for decentralized time stamping right now.
Whenever I publish something I made, I submit the URL to the Wayback Machine so if it gets hugged to death at least there's a public copy somewhere else.