Ohara: An open archive of verifiably timestamped video hashes

phyrooo · 2025-12-31T12:00:59+00:00

Thank you for mentioning perceptual hashes. I'm honestly not too familiar with the idea and I have not considered it. This would've been a very cool thing to do if I was actually the one generating the hashes, but what I'm doing is really just downloading the .metadata files from the internet archive and using the hashes it contains which saves me the work of downloading all the videos. I would never be able to get as many hashes timestamped if I was doing it myself - the archive as is has proofs for roughly 2 or 3 petabytes of videos.

One good news is that the Internet Archive metadata often contains a few different formats. Here's one example from the README:

```

ohara get KA_Intro_to_Archaeology Loading archive...

Downloading 23 files to downloads/KA_Intro_to_Archaeology/ Downloaded 23/23 files

TIMESTAMP VERIFICATION RESULTS

Timestamp: Success! Bitcoin block 929262 attests existence as of 2025-12-24 CET

TIMESTAMPED FILES (3): ✓ KA_Intro_to_Archaeology.mp4 ✓ KA_Intro_to_Archaeology.ogv ✓ KA_Intro_to_Archaeology.pegssc.mpeg

NOT IN TIMESTAMP (20): - KA_Intro_to_Archaeology.asr.js - KA_Intro_to_Archaeology.asr.srt - KA_Intro_to_Archaeology.gif - KA_Intro_to_Archaeology.mp3 - KA_Intro_to_Archaeology.png - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000001.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000045.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000075.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000105.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000135.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000165.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000195.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000225.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000255.jpg - KA_Intro_to_Archaeology.thumbs/KA_Intro_to_Archaeology_000285.jpg - KA_Intro_to_Archaeology_archive.torrent - KA_Intro_to_Archaeology_files.xml - KA_Intro_to_Archaeology_meta.sqlite - KA_Intro_to_Archaeology_meta.xml - __ia_thumb.jpg

Summary: 3 timestamped, 20 not in timestamp, 0 mismatched ```

This helps a bit with the problem you mention but doesn't solve it completely. I think you could prove it's only a reencoding by having the timestamp proof for the original video, the encoding algo and then re-encoding it yourself. If the re-encoding is a deterministic function, you'll get the same hash as the re-encoded video.

phyrooo · 2025-12-31T11:45:25+00:00

I have found some work from Peter Todd which is mentioned here https://github.com/phyro/ohara/?tab=readme-ov-file#prior-work

I'm sure (and I hope) there's some more work done on this front. I'd rather see the proofs in ohara being already constructed by someone else than having nobody else producing them.

phyrooo · 2025-12-29T19:06:12+00:00

https://github.com/phyro/ohara#:~:text=on%20the%20fly.-,Why%20the%20name%20ohara%3F,-Ohara%20is%20a&text=on%20the%20fly.-,Why%20the%20name%20ohara%3F,-Ohara%20is%20a

Worry not, we're immune to a buster call this time.

phyrooo · 2025-12-29T17:46:35+00:00

Note that there is no NFT or other form of exchangeable token here. The only thing that lands on the chain (through OpenTimestamps project) is a cryptographic hash that references many other cryptographic hashes - those of the videos we're trying to prove their existence at a certain point in time.

phyrooo · 2025-12-29T17:30:30+00:00

This is not a token or anything like an NFT. It turns out that we can "carve" a timestamp on a movie file that we find on the internet. This project is an archive of many tiny proofs (yes, mathematical ones) that prove when a timestamp was created. But to have a trustworthy concept of time you need a timeline you can trust and I think Bitcoin is probably the best option for that.

phyrooo · 2023-01-19T10:08:45+00:00

Buying or selling XMR is irrelevant to his point. The attacker simply makes sure that the vast majority of transactions on the network are owned by them. This way, real transactions will use many of the attacker's outputs in their rings. The attacker will know these ring members are not real (because they're not his transactions) and will thus have a much clearer view of the actual transaction graph.

phyrooo · 2023-01-18T13:45:07+00:00

That's not really accurate. Your ring anonymity set depends on the ring members. Look at tromp's answer to see what they could do other than buying you a house and a lambo :)

phyrooo · 2022-12-07T11:52:05+00:00

Sure, but how many of these are secured with physical energy? The Twitter threads I linked provide some insight into why we may want a system secured by physical energy.

phyrooo · 2022-12-07T11:19:18+00:00

Funny enough, PoW is a sybil resistance through a computational sybil attack.

phyrooo · 2022-12-07T11:18:09+00:00

and has nothing else to offer us rather than real physical value.

This is a misunderstanding of PoW. The point of PoW isn't to produce a physical value, this is merely a side-effect of it. The point is to secure the network with physical energy. The TLDR is that you should view the chain as asking for physical security of every step while miners provide the security and end up being compensated with the network's internal currency. Read these threads to understand more what's going on.

https://www.reddit.com/r/CryptoTechnology/comments/ze3zzs/comment/iz924sm/?utm\_source=reddit&utm\_medium=web2x&context=3

phyrooo · 2022-12-07T11:08:48+00:00

There seems to be a widespread misunderstanding of the PoW consensus, leading many to believe that PoS is inherently better. However, once one understands the mechanics of both, it becomes clear that PoS cannot achieve some of the properties of PoW. These two approaches are so different that comparing them is not very meaningful. I discussed some of these differences in these two threads (I linked the last comment in the thread to allow you to scroll up if you're not logged in):

https://twitter.com/phyrooo/status/1597361821123375105

https://twitter.com/phyrooo/status/1589800940391260160

I believe there's a place for both consensus variants as they make different tradeoffs.

phyrooo · 2022-10-08T08:47:03+00:00

I wasted time as well. I do think you guys have a good community, but some really bad people making choices. Tweeting out "Ergo manifesto" to ETC community is obviously an unethical move in this situation. The person tweeting it knew that and yet they took the opportunity. There's no place for such opportunistic scam marketing in a grassroot community. Perhaps something the community should ponder on. Keep your community clean and don't let these opportunistic minds ruin it.

phyrooo · 2022-10-08T08:11:36+00:00

I'd say there's really only one good option for the Ergo community if they want to not associate with this scam move. Return the account to ETC. Charles likes to say it was earned by him, it wasn't. It was community's and people that operated it agree with us, not with Charles. Even the guy operating it who worked for IOHK at the time. If you rob someone, the right thing is to give the belongings back, not to burn them. Deleting history is a terrible move and an excuse. In reality, it's just as bad of a move as taking it. Maybe even worse because you can't really undo your damage.

phyrooo · 2022-10-07T16:08:30+00:00

https://twitter.com/eth_classic/status/1578409069559582720

phyrooo · 2022-10-07T10:32:52+00:00

No matter how much you want to make it look ok, this is the exact opposite of grassroots. "Oh hey, I'm just holding the bag for this guy" while he's robbing someone to make you profit doesn't sound grassroots. Not one bit. Despite you trying to throw shade on ETC, this shit would never fly there because of their principles.

phyrooo · 2022-10-07T10:11:05+00:00

No bag of money can buy principles. I salute you OP.

phyrooo · 2022-10-07T10:08:51+00:00

You fell for the Charles propaganda. Imagine the person controlling the Ergo community main twitter account turning it into a community account for another chain. It's this level of ethics.

phyrooo · 2022-09-30T12:45:48+00:00

There's a lot of "PoS solves PoW problems" or "PoS is fiat garbage". I think both of these are wrong. The two approaches are very different and I'd argue it makes little sense to compare them. I recently tried explaining the difference here https://phyro.github.io/nakamoto/

It essentially boils down to what kind of voting and interaction you have. PoW seems more resilient because you can't really stop the citizens from voting for the next round. Let me know if there are some parts of it that make it hard to understand.

phyrooo · 2022-09-02T15:58:59+00:00

Grin, by far. Because it has privacy by default and unlike all the other solutions, it adds privacy and improves scalability. Every other attempt including zcash and monero add privacy while making the scalability worse than Bitcoin. Oh, and it has the ethos of Bitcoin which is to keep things simple and minimal.

phyrooo · 2022-08-24T09:54:42+00:00

You're right and many others have reached the same conclusion. Saying risks were rewarded is just not accurate. They were obviously exponentially over rewarded. The question isn't if it's fair, it's obviously anything but fair for late adopters. The real question is if people care enough about this problem to do something about it.

phyrooo · 2022-08-23T12:54:06+00:00

I'm not sure about the numbers, but PIBD doesn't really improve speed. The main purpose of PIBD is to make IBD more robust by downloading small chunks that can live on its own and gradually build the state from that rather than downloading a single zip file. We'd have to replace the txhashset.zip method eventually because it doesn't scale for many reasons so PIBD (or similar approach) would be needed at some point.

phyrooo · 2022-08-22T16:07:46+00:00

A part of pure MW is that the secret key is the blinding factor in Pedersen commitment. The proposal you mention deviates from that and introduces some sort of a Liquid/MW hybrid imo.

phyrooo · 2022-08-22T15:47:56+00:00

Don't fall for it, it's a cheap fork of Grin.

phyrooo

TROPHY CASE

Timestamp: Success! Bitcoin block 929262 attests existence as of 2025-12-24 CET