Proving a proof-of-work solve happened, at a specific time, without trusting the server's logs
The problem: a solve is a fact that only lives in one server's memory If you gate a route with proof-of-work, every accepted solve is a real event. Someone burned real compute, at a real wall-clock moment, to get past the gate. That is exactly the property you wanted: the gate costs the caller something. But where does that fact live? In the verifier's memory, for as long as the process stays up.…
PowForge's solve-witness mechanism provides a way to prove that a Proof-of-Work (PoW) solve occurred at a specific time without relying on the server's logs. This is accomplished by using Merkle-fold to compress a window of accepted solves into a single witness hash, which is then anchored to a Bitcoin OpenTimestamps (OTS) calendar.
The process involves creating a leaf hash for each solve that includes the challenge salt, winning nonce, and server's HMAC signature, and then appending these leaves to a batch. Every fixed interval (default 10 minutes), the batch is sealed, and its Merkle root is submitted to an OTS calendar, anchoring the entire window to the Bitcoin blockchain with a single timestamp.
This allows anyone to verify the inclusion of a specific solve by providing the leaf hash, Merkle inclusion path, and witness hash from the OTS proof, all of which can be recomputed using SHA-256. The mechanism ensures that the cost of anchoring the batch is constant, regardless of the number of solves within the window. The provided demo server showcases this process, creating a live Express app with the necessary middleware to handle PoW challenges and proofs, and successfully generating a real OTS proof.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — it may contain errors, so check the original before relying on it.
