Adam Back

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Adam Back
BornJuly 1970 (age 53)
London, England, UK
EducationUniversity of Exeter
Scientific career
ThesisParallelization of general purpose programs using optimistic techniques from parallel discrete event simulation (1995)
Doctoral advisorStephen Turner

Adam Back (born July 1970) is a British cryptographer and cypherpunk. He is the CEO of Blockstream, which he co-founded in 2014. He invented Hashcash, which is used in the Bitcoin mining process.


Back was born in London, England, in July 1970.[1] His first computer was a Sinclair ZX81. He taught himself Basic, and spent his time reverse engineering video games, finding decryption keys in software packages. He completed his A levels in advanced mathematics, physics and economics.

He has a computer science PhD in distributed systems from the University of Exeter.[2] During his PhD, Back worked with compilers to make use of parallel computers in a semi automated way. He became interested in pgp encryption, electronic cash and remailers. He spent two thirds of his time working with encryption. After graduation, Adam spent his career as a consultant in start ups and larger companies in applied cryptography, writing cryptographic libraries, designing, reviewing and breaking other people's cryptographic protocols.[3]

Cryptography software[edit]

Back's "Munitions" T-shirt featured computer code that was considered to be a weapon in the United States.

Back is a pioneer of early digital asset research similarly as Wei Dai, David Chaum, and Hal Finney.[4][5] In 1997, Back invented Hashcash.[6] A similar system is used in bitcoin.[7][8][9]

He also implemented credlib,[10][better source needed][11][better source needed] a library that implements the credential systems of Stefan Brands and David Chaum.

He was the first to describe the "non-interactive forward secrecy"[12][13][14] security property for email and to observe that any identity based encryption scheme can be used to provide non-interactive forward secrecy.

He is also known for promoting the use of ultra-compact code with his 2-line[15] and 3-line RSA in Perl[16][17][18] signature file and non-exportable T-shirts[19][20] to protest cryptography export regulations.[21]

Back was one of the first two people to receive an email from Satoshi Nakamoto.[22][2] In 2016, the Financial Times cited Back as a potential Nakamoto candidate, along with Nick Szabo and Hal Finney.[23] Craig Wright had sued Back for stating that Wright was not Nakamoto, with Wright subsequently dropping the suit.[2]

Back has promoted the use of satellites and mesh networks to broadcast and receive bitcoin transactions, as a backup for the traditional internet.[24]

Business career[edit]

On 3 October 2016, Back was appointed as CEO of Blockstream.[25] Since then he has introduced products such as the Liquid sidechain, Blockstream Mining Notes, mining colocation services, the Jade hardware wallet, and the Core Lightning implementation.


  1. ^ Singh, Rachna (2019). The Bitcoin Saga: A Mixed Montage. Bloomsbury Publishing. ISBN 978-9388271837.
  2. ^ a b c Kharif, Olga (2 June 2020). "Latest Satoshi Nakamoto Candidate Buying Bitcoin No Matter What". Bloomberg. Retrieved 3 June 2020.
  3. ^ "Proof of Work - An interview with Adam Back (Blockstream)". YouTube. Archived from the original on 15 December 2021.
  4. ^ Leising, Matthew (30 June 2018). "Is Bitcoin Creator Writing a Book? Cryptic Note Indicates Yes". Bloomberg. Retrieved 13 May 2020.
  5. ^ Bustillos, Maria (25 August 2015). "Inside the Fight Over Bitcoin's Future". New Yorker. Retrieved 13 May 2020.
  6. ^ Narayanan, Arvind; Bonneau, Joseph; Felten, Edward; Miller, Andrew; Goldfeder, Steven (2016). Bitcoin and Cryptocurrency Technologies: A Comprehensive Introduction. Princeton and Oxford: Princeton University Press. ISBN 978-0-691-17169-2.
  7. ^ Shaw, Jessica Marmor (8 January 2018). "Bitcoin and cryptocurrency on Twitter: The most important people to follow". Marketwatch. Retrieved 14 May 2020.
  8. ^ "Bitcoin: A Peer-to-Peer Electronic Cash System" (PDF).
  9. ^ Casey, Michael J. (22 October 2020). "BitBeat: Bitcoin Coding Allstars Launch Sidechains Project to Boost Innovation". WSJBlogs. Retrieved 14 May 2020.
  10. ^ Frisby, Dominic (2015). "Footnotes". Bitcoin: The future of money?. Unbound. ISBN 978-1783521029.
  11. ^ "credlib - Credential Library".
  12. ^ Boyd, Colin. "A Modern View on Forward Security" (PDF). IACR. Retrieved 14 May 2020.
  13. ^ Anderson, Ross (2002). "Two remarks on public key cryptology" (PDF). Cambridge University. Retrieved 14 May 2020.
  14. ^ "Non-Interactive Forward Secrecy".
  15. ^ Salomon, David (2003). "Secure Programming with Perl". Data Privacy and Security. Springer. p. 200. ISBN 9781441918161.
  16. ^ Judmayer, Aljosha; Stifter, Nicholas (2017). "Before bitcoin". Blocks and Chains: Introduction to Bitcoin, Cryptocurrencies, and Their Consensus Mechanisms (Synthesis Lectures on Information Security, Privacy, and Tru). Morgan & Claypool Publishers. p. 17. ISBN 9781627057165.
  17. ^ "export-a-crypto-system sig".
  18. ^ Sinn, Richard (2007). "Secure Programming with Perl". Software Security Technologies. Cengage Learning. p. 366. ISBN 9781428319455.
  19. ^ Blanchette, Jean-François (2012). "On the brink of revolution". Burdens of Proof: Cryptographic Culture and Evidence Law in the Age of Electronic Documents. MIT Press. p. 50. ISBN 978-0262017510.
  20. ^ "Munitions T-shirt".
  21. ^ Brunton, Finn (2019). "On the brink of revolution". Digital Cash: The Unknown History of the Anarchists, Utopians, and Technologists Who Created Cryptocurrency. Princeton Press. p. 97. ISBN 9780691179490.
  22. ^ RATLIFF, EVAN (16 July 2019). "Was Bitcoin Created by This International Drug Dealer? Maybe!". Wired. Retrieved 13 May 2020.
  23. ^ Kaminska, Izabella (7 May 2016). "Bitcoin: Identity crisis". Financial Times. Retrieved 4 June 2020.
  24. ^ del Castillo, Michael (17 December 2018). "Who Needs Verizon? Blockstream Broadcasts Entire Bitcoin Blockchain From Space". Forbes. Retrieved 13 May 2020.
  25. ^ Blockstream (3 October 2016). "Blockstream Appoints Hashcash Inventor Dr. Adam Back as CEO". PR News Wire. Retrieved 2020-12-05.

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