# Adam Back

> Adam Back is a British cryptographer, Hashcash inventor, and co-founder and CEO of Blockstream. His 1997 anti-spam system helped inform Bitcoin’s proof of work. With a PhD from the University of Exeter and a career in privacy technology, he now leads a company developing Bitcoin wallets, sidechain software, and financial infrastructure.

- **Role:** Co-Founder & CEO at Blockstream
- **Organizations:** Blockstream, Pi Corporation, EMC, Zero-Knowledge Systems
- **From:** London, United Kingdom
- **Nationality:** British
- **Education:** PhD in computer science; research in distributed systems, University of Exeter
- **Known for:** Invented Hashcash, cited in the Bitcoin white paper as a precursor to its proof-of-work mechanism., Co-founded Blockstream in 2014., Co-authored the 2014 pegged-sidechains proposal.

## Career timeline

- **1995** — Completed his computer science PhD at the University of Exeter.
- **1997** — Introduced Hashcash, a computational proof-of-work system intended to deter spam and resource abuse.
- **2002** — Published Hashcash - A Denial of Service Counter-Measure.
- **2008** — Corresponded with Satoshi Nakamoto; Bitcoin’s white paper cited his Hashcash paper.
- **2014** — Co-founded Blockstream and co-authored Enabling Blockchain Innovations with Pegged Sidechains.
- **2016** — Appointed Blockstream CEO on October 3.
- **2017** — Co-authored the Confidential Assets research paper.

## Achievements

- Invented Hashcash, cited in the Bitcoin white paper as a precursor to its proof-of-work mechanism.
- Co-founded Blockstream in 2014.
- Co-authored the 2014 pegged-sidechains proposal.
- Co-authored research on Confidential Assets.
- Co-founded Pi Corporation, later acquired by EMC; subsequently served as chief security officer of EMC’s consumer division.

## Latest updates

- **2026-10** — Blockstream, led by Back, announced the return of multisig account creation in its app on October 13, including 2-of-2 and Bitcoin 2-of-3 options.
- **2026-09** — Blockstream published its Liquid Network security incident assessment on September 23, describing a September 6 exploit, chain recovery, and reserve recovery efforts; recovery remained ongoing at publication.
- **2026-04** — Back denied being Satoshi Nakamoto following a New York Times investigation suggesting that identity; the claim is not established.

## Links

- Website: http://www.cypherspace.org/adam/
- Twitter/X: https://x.com/adam3us
- GitHub: https://github.com/adam3us

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Profile page: https://yespress.io/adam-back
Published by YesPress — https://yespress.io
Last updated: 2026-10-16