Security model
Signet is built so that no single party, Signet included, can invent people, link a person across businesses, or act as them. This page lists what Signet stops, what it relies on, and its limits at launch.
What Signet stops
| Attempt | What happens |
|---|---|
| A bot with no verified person behind it | It cannot open a session, so a business never allows it a protected action |
| One person sending many agents or accounts to claim a per-person allowance again | Stopped after the first: all their agents share one private identifier at that business, and one count |
| Replaying a captured request | Refused: every request is single-use and expires quickly |
| An agent going beyond its permission | Refused: each request is checked against the agent's permission and the business's policy |
| A compromised agent | Limited to that agent's short-lived permission. It never holds the person's secret |
| Businesses comparing notes to track a person | Not possible: each business sees a different identifier, and no one can link them without the person's secret |
| Enrolling with a photocopy of a passport | Not possible: enrolling needs the issuing country's signature, read from the passport's chip |
| The registry adding people who never enrolled | Caught: witnesses check the proof behind every new entry before they co-sign |
| The registry showing one device a registry of its own | Rejected: businesses accept only recent epoch roots that witnesses co-signed |
| Signet acting as a person | Not possible: only the person's device holds their secret and keys |
What it relies on
- Issuing authorities issue each identity document to one real person and keep their signing keys safe.
- Witnesses: enough of them are honest. A business accepts a checkpoint only when enough witnesses have co-signed it.
- The person's device keeps their secret and keys safe in its secure hardware. Whoever controls an unlocked device can use the identity on it.
- Cryptography: the zero-knowledge proofs, signatures and hash functions Signet uses are sound.
Limits at launch
- Passports, not people. Signet counts passports. A person with two valid passports, such as a second passport, a passport from a second nationality or a cancelled but unexpired one, can enroll twice.
- Copied chip data. Someone who has read a passport's chip, such as a system that scanned it or a malicious app, could enroll it before its owner does.
- Bans and new secrets. When a person replaces their secret, their private identifier changes at every business, so a business's ban on the old identifier no longer applies. Signet limits how often a person can replace their secret.
- One identifier per business. A business can link everything a person does with it. This is deliberate: it is what makes per-person limits work.
- Signet runs the registry and the witnesses. At launch there is one registry, so Signet could refuse or delay an enrollment. While Signet also runs every witness, the witnesses catch mistakes and outside attackers, but not Signet itself.