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Comment by kens | Hacker News Reader

Back in 1990, Bellcore researchers Haber and Stornetta set up a system (surety.com) where documents were hashed and then the hash value was published as a classified ad in the New York Times every week. This provided a solid proof that the document was published as of that date. (Unless someone visited all the world's libraries and swapped in fake New York Times copies.)

An article showing one of the classified ads: https://www.vice.com/en/article/j5nzx4/what-was-the-first-bl...

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The problem with this approach for many applications is that you can potentially publish many messages and then only tell any about the ones you want to 'keep'. For instance if you want to predict an election outcome, publish hashes for both outcomes under different names and then only tell people about the winning one later on.

This is where reputation becomes important. Attach your name to a public message and hash and it’s easy to verify that you didn’t predict both outcomes. Continuing to use the same channel over time provides further weight.

The flip side of this is so many people make so many predictions that getting any one the correct is effectively meaningless most of the time. Essentially, you need a long string of public predictions on a single channel for it to be meaningful anyway.

It used to be a common email scam that you’d make two opposite market predictions and send them as free advice. Then you’d do the same thing the next month, but only send to the people who received the “correct” first message. And again. And again. And when you had “proven” yourself all-knowing to a small group of people, you’d start charging them.

Which is why being public is so important for these things.

Derren Brown did this with horse races IIRC for a TV show.

https://derrenbrown.co.uk/shows/the-system/

Can confirm. Learned something from that.

this is cool. i've heard of this as a theoretical way, but didn't know anyone was actually publishing hashes in a real newspaper!

I’ve seen it happen several times on twitter.

“Our” own patio11 has done it at least once recently.

Speaking of stealing newspapers to suppress the truth...

https://threadreaderapp.com/thread/1315314371560579073.html

5th degree theft? What is this? (Not too familiar with the US legal system)

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