Satoshi ↔ Adam Back Correspondence

I’m getting ready to release a paper that expands on your ideas into a complete working system.

I wanted to make sure I have the citation to your hashcash paper right.

[Satoshi included a link to a pre-release draft of what would become the Bitcoin whitepaper. The draft was titled “Electronic Cash Without a Trusted Third Party” and filed as ecash.pdf — predating the October 3 draft which was retitled to “Bitcoin: A Peer-to-Peer Electronic Cash System.”]

[Source: This email was entered into evidence during the COPA v. Craig Wright trial in London, February 2024. Adam Back filed the complete email chain as a witness statement.]

[Adam Back confirmed the citation and suggested Satoshi look at Wei Dai’s b-money proposal.]

[Satoshi subsequently replied: “Thanks, I wasn’t aware of the b-money page, but my ideas start from exactly that point.” He then contacted Wei Dai directly on August 22, 2008, and cited b-money in the Bitcoin whitepaper.]

[Source: This email was entered into evidence during the COPA v. Craig Wright trial in London, February 2024. The complete email chain (5 emails total) was filed by Adam Back as a witness statement. Only the first two emails (Satoshi’s initial contact and Back’s reply) are archived here; the remaining three have not been published in full.]

In this third email of the chain, Satoshi thanked Adam Back for pointing him to Wei Dai’s b-money proposal and made a historically significant admission:

Thanks, I wasn’t aware of the b-money page, but my ideas start from exactly that point.

This statement is important for two reasons: it establishes that Satoshi developed Bitcoin’s core ideas independently of b-money before learning of Dai’s work, and it confirms that b-money was added to the Bitcoin whitepaper’s references only after Back’s suggestion.

Satoshi also described the technical approach of his system:

[Satoshi explained how the system uses proof-of-work for coin generation and network timestamping, describing the chain of hash-based proof-of-work to create self-evident proof of the majority consensus.]

Following this exchange, Satoshi contacted Wei Dai directly on August 22, 2008, initiating a separate correspondence that would lead to b-money being cited as reference [1] in the Bitcoin whitepaper.

[Source: Filed as exhibit evidence in the COPA v. Craig Wright trial, London, February 2024. Adam Back’s Second Witness Statement (document C/21, dated November 7, 2023) included the complete five-email chain. Published in Bitcoin Magazine.]

In this fourth email of the chain, Adam Back suggested another paper Satoshi might find interesting: “MicroMint” by Ron Rivest et al. (1996), which explored extracting k-way hash collisions rather than the partial pre-images used by Hashcash and Bitcoin.

[Back suggested the MicroMint paper as a related work on computational puzzles for digital currency.]

Notably, Back had still not read Satoshi’s attached draft paper (ecash.pdf) at this point. He later publicly acknowledged this oversight in a Cointelegraph interview, saying it was “probably my biggest mistake.” Back would not actively engage with Bitcoin until 2013, missing the opportunity to be involved from the very beginning despite being one of the first people Satoshi contacted.

The exchange ended here for nearly five months, until Satoshi wrote again on January 10, 2009 — the day after Bitcoin’s public launch.

[Source: Filed as exhibit evidence in the COPA v. Craig Wright trial, London, February 2024. Adam Back’s Second Witness Statement (document C/21) included the complete five-email chain. Back’s regret about not reading the paper was discussed in a Cointelegraph interview.]

Nearly five months after their last exchange, Satoshi wrote to Adam Back for the final time. Bitcoin v0.1 had been released on January 9, 2009, and Satoshi personally notified Back of the launch.

[Satoshi thanked Back again for suggesting the b-money and MicroMint papers during their August 2008 correspondence, and announced that the open-source Bitcoin software had been launched. He included Hal Finney’s overview of the project from the Cryptography mailing list discussion.]

This email is the last known direct communication between Satoshi and Adam Back. Back did not engage with Bitcoin at this time and would not become actively involved until 2013. He later founded Blockstream in 2014.

The five-email chain between Satoshi and Adam Back — spanning from August 20, 2008 to January 10, 2009 — documents one of the most significant intellectual connections in Bitcoin’s prehistory: Satoshi’s outreach to the creator of Hashcash, which led to the discovery of Wei Dai’s b-money and shaped the final Bitcoin whitepaper.

[Source: Filed as exhibit evidence in the COPA v. Craig Wright trial, London, February 2024. Adam Back’s Second Witness Statement (document C/21) included the complete five-email chain.]