Below are 3 emails between cryptographer Wei Dai and Satoshi Nakamoto.
…I believe it was me who got Wei Dai’s b-money reference added to Satoshi’s bitcoin paper when he emailed me about hashcash back in 2008.
From this we can conclude that although Satoshi would go on to reference Wei Dai’s b-money in the Bitcoin White Paper, he invented Bitcoin independently of b-money.
Dai himself questions b-money’s influence on Bitcoin:
…my understanding is that the creator of Bitcoin, who goes by the name Satoshi Nakamoto, didn’t even read my article before reinventing the idea himself. He learned about it afterward and credited me in his paper. So my connection with the project is quite limited.
In any case, since Adam back has not yet released his email with Satoshi, these are the earliest documented communications by Satoshi Nakamoto:
Sent: Friday, August 22, 2008 4:38 PM
To: “Wei Dai” <firstname.lastname@example.org>
Cc: “Satoshi Nakamoto” <email@example.com>
Subject: Citation of your b-money page
I was very interested to read your b-money page. I’m getting ready to release a paper that expands on your ideas into a complete working system. Adam Back (hashcash.org) noticed the similarities and pointed me to your site.
I need to find out the year of publication of your b-money page for the citation in my paper. It’ll look like:
 W. Dai, “b-money,” http://www.weidai.com/bmoney.txt, (2006?).
You can download a pre-release draft at
http://www.upload.ae/file/6157/ecash-pdf.html Feel free to forward it to anyone else you think would be interested.
Title: Electronic Cash Without a Trusted Third Party
Abstract: A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without the burdens of going through a financial institution. Digital signatures offer part of the solution, but the main benefits are lost if a trusted party is still required to prevent double-spending. We propose a solution to the double-spending problem using a peer-to-peer network. The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work. The longest chain not only serves as proof of the sequence of events witnessed, but proof that it came from the largest pool of CPU power. As long as honest nodes control the most CPU power on the network, they can generate the longest chain and outpace any attackers. The network itself requires minimal structure. Messages are broadcasted on a best effort basis, and nodes can leave and rejoin the network at will, accepting the longest proof-of-work chain as proof of what happened while they were gone.
The second email in the sequence is the reply by Wei:
Here’s the archived post:
There are some discussions of it at
Thanks for letting me know about your paper. I’ll take a look at it and let you know if I have any comments or questions.
It is worth noting that the paper provided by Satoshi in this exchange is an early draft of what would become the Bitcoin White Paper. The full copy of that draft is available on NSI here.
Sent: Saturday, January 10, 2009 11:17 AM
Subject: Re: Citation of your b-money page
I wanted to let you know, I just released the full implementation of the paper I sent you a few months ago, Bitcoin v0.1. Details, download and screenshots are at www.bitcoin.org
I think it achieves nearly all the goals you set out to solve in your b-money paper.
The system is entirely decentralized, without any server or trusted parties. The network infrastructure can support a full range of escrow transactions and contracts, but for now the focus is on the basics of money and transactions.
There was a discussion of the design on the Cryptography mailing list. Hal Finney gave a good high-level overview:
| One thing I might mention is that in many ways bitcoin is two independent
| ideas: a way of solving the kinds of problems James lists here, of
| creating a globally consistent but decentralized database; and then using
| it for a system similar to Wei Dai’s b-money (which is referenced in the
| paper) but transaction/coin based rather than account based. Solving the
| global, massively decentralized database problem is arguably the harder
| part, as James emphasizes. The use of proof-of-work as a tool for this
| purpose is a novel idea well worth further review IMO.