Adam Back

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. An investigation by The New York Times suggested that he may be Satoshi Nakamoto, the pseudonymous inventor of bitcoin, though Back has denied this claim.

Life Back was born in London, England, in July 1970. 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. 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, Back spent his career as a consultant in startups and larger companies in applied cryptography, writing cryptographic libraries, designing, reviewing and breaking other people's cryptographic protocols.

Cryptography software 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 similar to Wei Dai, David Chaum, and Hal Finney. In 1997, Back invented Hashcash. A similar system is used in Bitcoin.

He also implemented credlib, a library that implements the credential systems of Stefan Brands and David Chaum.

He was the first to describe the "non-interactive forward secrecy" 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 and 3-line RSA in Perl signature block and non-exportable T-shirts to protest cryptography export regulations.

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

Relationship to Satoshi Nakamoto

Back was one of the first two people to receive an email from Satoshi Nakamoto, the pseudonymous inventor of bitcoin. Craig Wright had sued Back for stating that Wright was not Nakamoto, with Wright subsequently dropping the suit.

The 2024 HBO documentary Money Electric: The Bitcoin Mystery, directed by Cullen Hoback, examined Back as its principal Satoshi Nakamoto suspect, with Hoback stating that "the evidence pointing in Adam's direction was a lot harder to poke holes in." The film noted that Back is the only person named in the body of the Bitcoin white paper, and that Back's writing style resembles Nakamoto's. Hoback also highlighted Back's move to Malta, his edits to Wikipedia's Bitcoin article that restored its Nakamoto section and listed other suspects but not himself, and his joining the Bitcoin forum on April 17, 2013, the same day the size of Nakamoto's holdings first became public. In an on-camera interview for the documentary, after Hoback listed him among the suspects, Back replied: "I thought you might think I'm Satoshi. And I don't want that to be on the record, really."

Business career On 3 October 2016, Back was appointed as CEO of Blockstream.