An anonymous post on the Cypherpunks mailing list from 21 years ago discusses the idea of “ecash,” and the speculation in the crypto community is that it might belong to a pre-Bitcoin Satoshi Nakamoto.
“Cypherpunk” refers to a movement that emerged in the 1980s advocating cryptography and other privacy-enhancing technologies as tools for promoting social change. Many of the early Bitcoin supporters were part of the Cypherpunks mailing list, including Adam Back, Hal Finney, and Nick Szabo.
We do not know with any certainty whether Satoshi Nakamoto was ever part of the forum, but he surely would have been familiar with the ideas percolating there. Many of those ideas formed the basis for what Nakamoto ultimately finalized in Bitcoin.
When this old post discussing “ecash” resurfaced, it was easy to connect the dots to present-day Bitcoin. Recall that the full name of the Bitcoin whitepaper is “Bitcoin: A Peer-to-Peer Electronic Cash System.”
The anonymous author of the Cypherpunks post discusses the necessary prerequisites of digital cash, one feature of which is called “blinding:”
“I wouldn't say ecash has to use blinding, but I would argue it would be a misuse of the word “ecash", if something which was revocable were dubbed ecash.”
“Blinding” likely refers to the idea of a cryptographic blind signature, introduced by David Chaum. It lets people securely sign data without revealing it, and then verifies that the data has not been tampered with. This functionality has become commonplace in the wake of Bitcoin and other cryptocurrencies.
The author of the anonymous post goes on to discuss another key obstacle that any electronic currency faces: the double spend problem.
“One possibility is to make the double-spending database public. Whenever someone receives a coin they broadcast its value. The DB [database] operates in parallel across a large number of servers so it is intractable to shut it down.”
He concludes his post by mentioning the two proposals for electronic money that were referenced in the Bitcoin whitepaper: Wei Dai’s b-money and Adam Back’s Hashcash:
“Another possible form of ecash could be based on Wei Dai's b-money. This is like hashcash, something which represents a measurable amount of computational work to produce. It therefore can't be forged. This could be a very robust payment system and is worth pursuing further.”
In the course of a 200-word post, the anonymous touches on every major issue facing a usable digital currency, and does so 10 years before Bitcoin pulled them all together. It’s certainly not enough to conclude that the author is Satoshi Nakamoto, but the resemblance is striking.