The Hashcash whitepaper was released by Adam Back

In 2002, Adam Back published an updated whitepaper on Hashcash, consolidating various applications, improvements, and experiences from using the system since its initial proposal in 1997. Hashcash was a proof-of-work system designed to combat the misuse of un-metered internet resources, such as email and anonymous remailers, by requiring a computationally expensive token to be generated for each use.
 

The Hashcash whitepaper of 2002 is significant because it detailed the practical applications of the proof-of-work concept, which would later become a fundamental component of Bitcoin’s architecture. Adam Back’s work on Hashcash provided a direct inspiration for the proof-of-work mechanism used in Bitcoin, which requires miners to solve complex mathematical problems to validate transactions and add new blocks to the blockchain.
 

Adam Back’s contribution to Bitcoin extends beyond the Hashcash algorithm. As a cryptographer and a prominent figure in the bitcoin space, his expertise in cryptography and his understanding of the challenges associated with digital currencies have made him a valuable contributor to the development of Bitcoin. His work on Hashcash laid the foundation for the decentralized consensus mechanism that underpins Bitcoin’s security and immutability.

Adam Back is now the CEO of a well known Bitcoin company called Blockstream,.