About

What it is

The Selective Disclosure Exchange Protocol (SDX Protocol) is an open protocol for how organisations share, address, and verifiably record encrypted data. It defines the message structure, the addressing scheme, and how records are anchored to the public audit layer. No single organisation owns it. The specification is public: you can read it at the specification today. The open, royalty-free licence that lets anyone implement it, fork it, and run their own instance is being finalised.

The protocol does not prescribe what data you share or with whom. It specifies how: how messages are addressed between parties, how they are signed, and how the fact of exchange is recorded in a way no participant can retrospectively alter. On top of the base protocol sit lightweight public taxonomies, one per field of work, that define which data is shared and what it means, plus a library of reusable exchange patterns. It builds on open standards throughout: key-derivation, identity and verifiable credentials (DID/VC, SD-JWT), and content provenance where relevant. Its full behaviour can be rebuilt and run independently.

Why it exists

Cross-organisational data exchange relies, by default, on intermediaries. Two organisations that want to share structured data typically end up routing through a third party: a platform, a hub, a clearinghouse, sometimes all three. That arrangement concentrates control. The intermediary sets the format and holds the routing table, and it becomes the single point of failure. Per-vendor integrations solve part of this but do not scale: each new connection brings its own agreement, its own format mapping, its own trust model.

An open protocol changes the problem. When the addressing scheme, the message format, and the audit trail are specified openly, any party can connect without asking permission. Records become independently verifiable, because the audit trail sits on the public audit layer, where no single party controls it. Control returns to the parties exchanging data: protocols, not platforms. The standard becomes shared infrastructure rather than a product someone can withdraw, which is what lets organisations, including public bodies exploring pilots, build on it without binding the exchange to one fixed service provider.

This is worth building carefully. An open standard that half the ecosystem ignores is not useful. That is why the licence, the governance process, and the hand-over conditions are documented in full at /governance.

Created by mintBlue

mintBlue initiated this standard and wrote the first specifications. That credit records origin, not ownership: the initiator holds no veto over the standard's direction, and how stewardship transfers, how the working group operates, and how changes to the normative core are ratified are all described at /governance.