Hourglass

Measurements: 19 October – 18 November 2026

Hourglass is the heartbeat of Sigelith. One core of our server computes, without a break, a chain of SHA-256 operations in which every step depends on the previous one, so the work cannot be spread across many computers. Every segment starts from a fresh Bitcoin block and the latest checkpoint of our log, and its result goes into the public log like an ordinary timestamp.

What it shows

Hourglass shows that between two events at least a given amount of time has passed — under an explicit assumption about hardware speed, which we are measuring right now. It measures elapsed time, not the hour: it does not tell what time it is, only how much time has passed at least.

How it works

It is a proof of sequential work by Cohen and Pietrzak (2018) on SHA-256: deterministic, with no committee and no trusted module. Every segment has a short proof (256 random checks) that you can verify on a laptop in Python, without our software.

What we are doing now

From 19 October to 18 November 2026 Hourglass runs on our production server, and we measure the stability of its speed, its interruptions and its agreement with the PTB clock. A segment takes about 1 h 51 min; each one is stamped in the public log and confirmed by the log's cosigners. The measurements began with the genesis timestamp, entry no. 453.

What we do not claim yet

• Hourglass is not on timestamp certificates yet. It will appear there after the measurements end.
• We assume that nobody computes more than 20 times faster than our server. The assumption has a margin, but only the measurements will confirm it.
• These are lower bounds only, and modest ones with such a cautious assumption: a week of computing proves about 6 hours.
• Hourglass gives no randomness and no encryption to the future (as drand does), and it runs at a single operator. It can be stopped, but it cannot be faked silently.

Check it yourself

The code, the specification and the verifier: github.com/DeiFlagellum/sigelith-hourglass (Apache-2.0).

What comes next

After 18 November we will analyse the measurements and publish a note. Then entries will show a minimum age — on the certificate as well.