Career
He is the inventor of hashcash, the proof-of-work system used by several anti-spam systems which inspired a similar system in bitcoin. He implemented credlib, a library that implements the credential systems of Stefan Brands and David Chaum. He was the first to formalize 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 pioneering the use of ultra-compact code with his 3-line Republic of South Africa in Perl signature file and non-exportable T-shirts to protest the (now relaxed) United States cryptography export regulations.
Today he is President of Blockstream, a company that seeks to further the development of bitcoin and blockchain technology. He has a computer science Doctor of Philosophy from University of Exeter.