On August 1, 2002, Adam Back officially presented the Hashcash paper, a precursor to the system used in Bitcoin mining.
In 1997, Adam Back, a British cryptographer and cypherpunk, proposed Hashcash, a mechanism designed to combat email spam and denial-of-service (DoS) attacks. It was a proof-of-work algorithm that required a certain amount of computational work to send an email, making spam sending uneconomical.
Five years later, on August 1, 2002, Back more formally described the functioning of Hashcash in the paper “Hashcash – A Denial of Service Counter-Measure,” which would later be cited in the Bitcoin white paper.
Hashcash laid the foundation for SHA256.
PoW!
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What do you mean? SHA256 is just a hash function. There are many hash functions PoW could use and be equally good.
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Happy Birthday Hashcash!

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Adam Back was ahead of his time
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I would say he's an alien from his own time 👽
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Thanks for sharing this reminder. Proof of Work
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Adam Back is a living legend. He's appreciated.
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Hashcash was the foundation to change the money systems for humanity. We must remember this day with grand respect.
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