Glossary

The terms these pages use, in alphabetical order.

Term	Meaning
Checkpoint	A signed snapshot of the registry's log: its size and root hash.
Commitment	A person's entry in the registry: a value derived from their secret that reveals nothing about them.
Consistency proof	A proof that a later version of the log only added entries to an earlier one, without changing, removing or reordering any.
Co-sign	A witness's signature on a checkpoint, added only after it has checked every change.
Device	The person's own device. It checks their identity document, holds their secret and keys, and makes every proof.
Document signer	The key an issuing country uses to sign the data on a passport's chip.
Document tag	A value derived from an identity document that lets the registry accept each document only once.
Enrollment	Joining the registry, once per person, by proving that an identity document is genuine.
Epoch root	The one registry root marked for each fixed period. Devices prove against the current one.
Inclusion proof	A proof that an entry is in the registry's log.
Issuing authority	The body that signed an identity document for its issuing country.
MCP	The Model Context Protocol, an open standard AI agents use to call tools. Signet Agent connects through it.
Merchant SDK	The library a business runs on its own server to check agents' requests. Coming soon.
Merkle tree	A tree of hashes whose single root commits to every entry, so an entry can be shown to be present with a short proof.
OHTTP	Oblivious HTTP: a request sent through a relay, so the relay sees the sender's address but not the request, and the server sees the request but not the address.
Permission	What a person's device signs for one of their agents: which actions it may take, how many times and until when. Also called a delegation.
Policy	A business's published rules: which actions need Signet, its per-person limits, and which actions need the person's approval.
Private identifier	The identifier a business sees for a person: the same at that business, different at every other. Also called a pseudonym. See Privacy and data.
Registry	Signet's list of everyone who has enrolled. See Registry.
Rotation	Replacing the person's secret. Their entry and every private identifier change.
Secret	A random value created on the person's device, not derived from their document. Their entry and private identifiers come from it.
Session	What a device opens with a business by proving that the person is in the registry. Later requests need only signature checks.
Signet Agent	Signet's integration for AI agents, through MCP. Coming soon.
Witness	An independent party, or a business that uses Signet, that checks every change to the registry and co-signs its checkpoints.
Zero-knowledge proof	A proof that a statement is true which shows none of the data behind it.