Platforms and nodes

libID works with three platforms: GitHub, X and Google. Each has a key, and the contracts identify it by the hash of that key:

platformId('github') // keccak256("github")

The keys are github, x and google.

Ids and handles

An identity, a platform account proved to a holder, has two things:

	GitHub	X	Google
Id	the numeric user id	the numeric user id	a SHA-256 digest of the account’s sub
Handle	the login, like octocat	the username, like jack	the email address

The id never changes. The handle can: users rename themselves, and platforms give old handles to new users.

Nodes

The contracts do not store strings as keys. They hash each id and each handle into a bytes32 key called a node:

idNode     = keccak256(abi.encode(keccak256("libid.identity.id-node.v1"),     platformId, keccak256(id)))
handleNode = keccak256(abi.encode(keccak256("libid.identity.handle-node.v1"), platformId, keccak256(handle)))

The platform is part of the node, so alice on X and alice on GitHub are different nodes.

You rarely compute nodes yourself. IdentityRegistry.handleNodeOf(platformId, handle) returns a handle’s node, and handleNode in the TypeScript package computes it locally.

Normalization

Before a handle is hashed, it is normalized, so that the different ways of writing one handle reach the same node:

• Letters are lowercased.
• On GitHub and X, one leading @ is removed.
• X allows _ but not -. GitHub allows - but not _. A - can never be first, last, or doubled.
• Handles longer than 15 characters on X, 39 on GitHub, or 62 for Google are refused.
• Only ASCII is allowed.

So @Octocat, octocat and OCTOCAT are the same GitHub handle. Text that breaks these rules is not a handle: resolveHandle returns the zero address for it, and handleNodeOf reverts with UnusableHandle.

The exact rules are in a shared table of test vectors; see handle normalization in the spec. IdentityRegistry.rulesOf(platformId) returns the rules a network uses.