Adam Back
Cryptographer, inventor of Hashcash, Blockstream CEO
- Known for
- Hashcash proof-of-work[2]
- Years active
- 2008–present[1]
- Key contribution
- Proof-of-work cited in the white paper[3]
- Notable date
- 1997: Hashcash proposed[1]
Photo: Adam Back portrait by Alexleso75 (photo by Alexandre Sitter), CC BY-SA 4.0, via Wikimedia Commons. Cropped.
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Bio
Adam Back is a British cryptographer and cypherpunk with a PhD in computer science from the University of Exeter.[1]
In 1997 he invented Hashcash, a proof-of-work system first aimed at email spam. The Bitcoin white paper cites Hashcash as the basis of its proof-of-work, and Back was one of the first people to receive an email from Satoshi Nakamoto.[1][2][3]
In 2014 he co-founded Blockstream, where he is CEO; Pieter Wuille and Gregory Maxwell were among the co-founders.[4][1]
Timeline
1997
Proposes Hashcash[1]
Oct 31, 2008
Hashcash cited in the white paper[3]
2014
Co-founds Blockstream[4]
Connections
Adam Back Hashcash cited in the white paper by Satoshi Nakamoto. Source
Hal Finney built RPOW on Hashcash-style proof-of-work by Adam Back. Source
Adam Back co-founded Blockstream with Pieter Wuille. Source
Adam Back co-founded Blockstream with Gregory Maxwell. Source
Elsewhere on CHC
Sources
Checked Oct 15, 2026 · All people