How it works

This is the short version. Read the briefs and the rationale first, on Learning. The construction and the implementation notes are on Technical.

Making one

You make a small file. It holds a public key and a record of work. The work is memory, held while the file is made. One leg is 2,000,000 steps over a 1 KB sample drawn from a 16 KB slot. The file stays small. The room it occupied does not travel with it.

Checking one

Anyone can check a file without holding its key. The verifier reads the file and recomputes. Checkpoints are checked in parallel. The record says what matched. That record is a measurement. A later policy is a separate decision.

Admission is a separate decision

A gate takes the measurement and applies its own policy. Groundinglab's sign-in policy uses a floor on the bookend pair: strict 7/20, default 1/4, lenient 1/8. The verifier does not apply that floor. The gate does. Those decisions are on the gate log.

Signing in

Sign in asks for a PCOC you hold. This site mints a code. Your app signs that code with the object. The gate checks the object's recorded work, then applies its policy. Verify does not make that decision.

The numbers

A stage binds to the stage's waypoint (or the seed value in stage 0). The maker observes a later Bitcoin block after a leg, and that observation dates the work. An anchor holds when the block is inside the 3-block window, that block is a stored stage interrupt, and the public index's plant matches. The largest object this gate accepts is 256 MiB.