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Okamoto, the renowned cryptographer, says his patent has been an obstacle to Hal Finney

July 5, 2020

Tatsuaki Okamoto explains why its The “electronic money” patent could have been an obstacle for Hal Finney in his quest to create his own electronic currency.

Six key patents

Just before December 6, 2004, Hal Finney searched a patent database on “POS systems based on blind digital signaturesHe published a list of six such patents on his website:

“That could be useful for those considering implementing electronic money“”

Four of the patents are from David Chaum, the other two from Okamoto and his colleague from the Nippon Telegraph, Kazuo Ohta.

Okamoto, the renowned cryptographer, says his patent has been an obstacle to Hal FinneyOkamoto, the renowned cryptographer, says his patent has been an obstacle to Hal Finney

Ecash patents from Dr. Okamoto and his Nippon Telegraph colleague Dr. Kazuo Ohta. Source: finney.org (via WayBack Machine)

Ecash patents from Dr. Okamoto and his colleague from the Nippon Telegraph, Dr. Kazuo Ohta. Source: finney.org (via WayBack Machine)

Okamoto He is currently the director of the Cryptography and Information Security Laboratory at NTT Research and have more than 100 patents. We asked him to explain why his patent could have been an obstacle to Hal Finney and other “cypherpunks” in their quest to create a decentralized currency, considering that an intermediary is involved in their patent.

Okamoto’s Ecash and Nakamoto’s Bitcoin

Okamoto kindly prepared diagrams that the Differences between the Ecash system described in your patent and that of Bitcoin (BTC).

Diagram: Electronic money, described in patent 49775595. Source: NTT Research

Diagram: Electronic money, described in patent 49775595. Source:
NTT research

Chart: Bitcoin. Source: NTT Research

Chart: Bitcoin. Source: NTT Research

Both solutions use public keys such as pseudonymous identities and private keys to authorize transactions. However, in Okamoto’s proposal, a trusted partner varies the transactions Bitcoin is not trustworthy and all nodes check transactions.

System without trust: no trivial achievement

Given this crucial difference, one might ask: why were Finney and other pioneers so paranoid about patent infringement? This is an obvious answer Satoshi Nakamoto’s Bitcoin proposal was the first successful framework for a trustworthy electronic money system. It was not a trivial achievement; Almost 30 years passed between the introduction of DigiCash by Chaum and Bitcoin by Nakamoto.

Did “Okamoto” Finney give ideas for “Nakamoto”?

Many believe that Finney is Satoshi Nakamoto, or at least part of the team behind the nickname. In addition to his interests, experience, and early participation in the world of Bitcoin, another fact strongly supports this theory: being a neighbor to Dorian Satoshi Nakamoto. Given that Google can’t return a single Satoshi Nakamoto query before Bitcoin’s proposal was released, this coincidence is worrying. If Finney is actually behind the pseudonym Satoshi Nakamoto, his familiarity with Tatsuaki Okamoto’s works may also have played a role in the selection of the alias..

Okamoto said Cointelegraph I’ve never been on the famous crypto mailing lists and that he didn’t know Hal Finney personally.

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