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August 2004Origins & cultureResearch & proposalsdocumented

Hal Finney builds reusable proofs of work

Finney released RPOW, a running system that let a proof-of-work token be handed on rather than spent once.

A trusted server exchanged a used token for a fresh one, with remote attestation intended to prove the server was running unmodified code. The design still depended on that single server behaving, which Bitcoin later removed the need for.