Privacy and data
Each party learns only what it needs for its part. The person's identity document and secret never leave their device.
What never leaves the device
- The identity document's details: the person's name, document number and date of birth. The photo on the document's chip is never read at all.
- The person's secret, from which their registry entry and every private identifier are derived.
- The device's private keys, held in its secure hardware.
What each party learns
| Party | Learns | Does not learn |
|---|---|---|
| Registry | That a genuine document enrolled, with the document's tag, expiry month and issuing authority, and the person's entry | The person's name or document details, their secret, or their private identifiers |
| Witnesses | What the registry learns, so they can check each change | The same as the registry |
| Business | The person's private identifier at that business, that a verified person stands behind each request, and the requests the person's agents send | The person's name or any document detail, their private identifier at any other business, or whether they use other businesses |
| AI agent | Its own key and the permission the device signed for it | The person's secret, their document, or their private identifiers |
Opening a session involves only the device and the business: the registry takes no part in it. Signet runs the registry only, so it never sees a business's traffic.
Private identifiers
A person's private identifier at a business is derived from their secret and that business's identity, with a keyed hash. So it is:
- the same at that business across all of the person's agents and accounts, which lets the business apply its rules per person;
- different at every other business, and no one without the person's secret can tell that two identifiers belong to the same person.
All of a person's activity at one business shares one identifier. This is deliberate: it is what makes per-person limits possible. If the person replaces their secret, their private identifier changes at every business.
What is stored, and where
| Where | What |
|---|---|
| Device | The person's secret, the device's keys, and its sessions and permissions |
| Registry | The public list of entries, the log of every change, and each document's tag, expiry month and issuing authority |
| Witnesses | Their own copy of each document's tag, to check that no document enrolls twice |
| Business | The private identifiers it has seen, its per-person counts, and the requests it chooses to keep |
Network addresses
From the first release, the device reaches the registry through Oblivious HTTP (RFC 9458) when it enrolls, replaces its secret or downloads what it needs to prove. A relay, run separately from the registry, sees the device's network address but not what it sends, and the registry sees what it sends but not the address. Witnesses and businesses see the network address of each request they receive, as any server does.