At the Crypto '98 conference, Hal Finney demonstrated the use of zero-knowledge proof based on the SHA-1 hash function. This step became significant for the future development of cryptography and privacy in blockchain technologies.
Importance of Zero-Knowledge Proofs for Crypto
Zero-knowledge proofs enable claims to be verified without the disclosure of information. Finney's demonstration used SHA-1, a widely used hashing function since 1995. He stated:
> "I want to prove to you that I know a message that hashes to a given hash value using the SHA-1 hash. I don’t want to reveal anything about the message." At a time when zero-knowledge proofs were considered slow and impractical, Finney showed they were feasible even with the limited computing power of the late '90s.
A Precursor to Bitcoin?
Hal Finney later became the first person to receive BTC from Satoshi Nakamoto in 2009, significantly contributing to early Bitcoin code and philosophy. His 1998 SHA-1 ZK demonstration reveals early engagement with private, provable cryptographic mechanisms, foundational to privacy-focused blockchain protocols.
What the 1998 Video Reveals
The rediscovered recording highlights Finney’s technical ingenuity and explains the protocol clearly: a prover calculates a SHA-1 hash of a secret message and commits to it, while a verifier checks consistency without seeing the message. It inspired later crypto applications, showing how privacy could be mathematically ensured even in open networks.
Hal Finney's zero-knowledge proof demonstration in 1998 was not just a cryptographic showcase—it was a forward-looking insight into what blockchain technologies would later demand: provable integrity with user privacy. It further proves why Finney is remembered as a visionary whose early work continues to shape the crypto landscape.
