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Adam Back

From Satoshipedia, the Satoshi Mail encyclopedia

Adam Back is a British cryptographer and cypherpunk who invented Hashcash in 1997,[1] a proof-of-work scheme for spam control.[2] Bitcoin's white paper cites it,[3] and Back was one of the first two people Satoshi is known to have emailed.[1]

The August 2008 emails

On 20 August 2008 Satoshi, writing from satoshi@anonymousspeech.com, asked Back to confirm a citation: “I'm getting ready to release a paper that references your Hashcash paper and I wanted to make sure I have the citation right.” He described the paper under its working title, Electronic Cash Without a Trusted Third Party. Back replied the next day that the citation looked fine and suggested Wei Dai's b-money proposal. Satoshi answered that evening: “I wasn't aware of the b-money page, but my ideas start from exactly that point.” (the emails). nakamoto-archive keeps a copy of the exchange.[4] Back's own copies, with their exact send times, were an exhibit to his witness statement in COPA v Wright, which also has Satoshi's last email to him, of 10 January 2009.[5]

Identity claims

Back co-founded Blockstream in 2014. He has been named as a possible Satoshi several times: by the Financial Times in 2016, and in April 2026 by a New York Times investigation by John Carreyrou, which pointed to less common phrases, shared niche interests and the timing of Satoshi's last communication and Back's first public comment on Bitcoin. Back denied it again.[1] See Identity of Satoshi Nakamoto.

In the archive

2 messages in 1 conversations with Satoshi.

See also

References

  1. Adam Back, Wikipedia (CC BY-SA 4.0). Retrieved 20 October 2026.
  2. Bitcoin, Wikipedia (CC BY-SA 4.0). Retrieved 20 October 2026.
  3. Satoshi Nakamoto, Bitcoin: A Peer-to-Peer Electronic Cash System, bitcoin.org.
  4. nakamoto-archive, “Complete archive of Satoshi Nakamoto's writings and productions”, GitHub. The README lists each source file with its origin, date and SHA-256 hash.
  5. Exhibit AB1 to the witness statement of Adam Back, COPA v Wright, in the trial documents.

Primary sources

The messages and commits this article draws on, in Satoshi Mail and where they were first published.

  1. Citation of your Hashcash paper, Private email with Adam Back, 20 August 2008. Original source

Published by Tyler Howell for Satoshi Mail. Written with AI assistance from the sources listed above and checked against them. Last updated 22 October 2026. Spotted an error? Email itstylerhowell@gmail.com (how articles are made).

Categories: People · Cypherpunks · Correspondents · Identity candidates