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.