Hal Finney was an early bitcoin contributor, cypherpunk and a developer at PGP Corporation.
In 1991, Finney started contributing to cryptographer Phil Zimmerman’s Pretty Good Privacy software project. Zimmerman later founded the PGP Corporation around the software, with Finney becoming its first employee in 1996.
Finney – a graduate of the California Institute of Technology – also built the first reusable proof-of-work system (RPoW), based on Adam Back’s Hashcash, with the intention of using it in a digital currency system. While not cited in the bitcoin white paper, bitcoin utilizes a decentralized peer-to-peer version of RPoW, the first widespread use of the system.
Finney operated two anonymous remailers – servers which receive messages and forward them to recipients without revealing their origin – and regularly participated in the cryptography mailing list via which the pseudonymous Satoshi Nakamoto first announced bitcoin.
Intrigued by Nakamoto’s idea when others were initially skeptical, Finney began running the bitcoin software shortly after its release and was likely the first person to do so after Nakamoto. Finney was also the recipient of the first bitcoin transaction: 10 bitcoin sent by Nakamoto.
“Bitcoin seems to be a very promising idea. I like the idea of basing security on the assumption that the CPU power of honest participants outweighs that of the attacker,” he said at the time.
While running the software, Finney corresponded with Nakamoto by email, which he claimed largely consisted of reporting bugs. He ceased running the software after several days, and did not look at bitcoin again until 2010.
Finney was diagnosed with amyotrophic lateral sclerosis (also called Lou Gehrig’s disease) in 2009, and retired from the PGP Corporation in 2011.
Although eventually paralyzed by the disease, Finney continued to code during his final years and wrote software for bitcoin with a computer that could track eye-movement. He died in 2014 at the age of 58.