British applied cryptographer Adam Back co-founded Blockstream in January 2014 and serves as its CEO. Blockstream is a blockchain technology company that promotes innovation in financial systems, focusing particularly on sidechains.
Having worked on e-cash protocols since 1995, in 1997 Back invented Hashcash, a proof-of-work system used to limit email spam and denial-of-service attacks. Hashcash is used in bitcoin and other cryptocurrencies as part of the mining algorithm.
He implemented credlib, a library that implements the credential systems of Stefan Brands and David Chaum.
Back is also known for pioneering the use of ultra-compact code with his 3-line RSA in Perl signature file and non-exportable T-shirts to protest the United States cryptography export regulations.
Back was an architect and cryptographer at Zero-Knowledge Systems working on its Freedom network, a precursor to Tor. He was an e-cash consultant to Nokia and later to Credentica (acquired by Microsoft), and has also consulted for leading security companies, including oneID, Vmware and QWcap.
In 2003 Back co-founded PI Corporation, where he was Chief Security Officer of the company's consumer division, Decho. PI Corporation was subsequently acquired by EMC.
Adam Back holds a Ph.D. in distributed systems and computer science from the University of Exeter.