Selective Disclosure

Selective disclosure allows a holder to present only the claims required for a declared purpose instead of revealing an entire credential or source document.

This supports a simple privacy principle: a verifier should receive enough information to answer its policy question, but not additional identity data merely because it exists.

A practical example

A service may need to know whether a person meets an age threshold. A traditional process may request a copy of an identity document containing full name, document number, exact date of birth, photograph, nationality, address, and other information.

A privacy-preserving presentation can instead provide the required age-related evidence, depending on the credential format and policy, without sharing every field from the document.

What selective disclosure changes

Traditional disclosure	Selective disclosure
The complete document or profile is shared.	Only required claims are presented.
The verifier receives unrelated information.	Disclosure is aligned with the declared purpose.
More data must be retained and protected.	The verifier can reduce collection and breach impact.
The holder has limited visibility.	The holder can review what is requested and disclosed.

Selective disclosure does not remove every privacy risk. A disclosed attribute may still be sensitive, and repeated presentations may still create correlation if identifiers or metadata are poorly designed. The surrounding policy remains important.

Conditions for a trustworthy presentation

A privacy-preserving presentation should still allow the verifier to evaluate:

• issuer provenance;
• integrity of the disclosed claims;
• credential status and validity;
• freshness of the transaction;
• the intended audience or requesting party;
• holder relationship where required;
• whether the disclosed set satisfies policy.

Privacy and assurance must be designed together. Revealing less information should not mean accepting evidence without appropriate verification.

Holder consent

The holder should be able to understand:

• who is requesting information;
• what claims are requested;
• why they are requested;
• what will be disclosed;
• what the expected result or service is.

Consent interfaces should not be used to shift all responsibility to the individual. Institutions must still limit requests, define lawful purpose, and avoid making unnecessary disclosure a condition where it is not justified.

Terminology

UbID uses the broader public term privacy-preserving verification for selective disclosure and related techniques.

The term zero-knowledge proof is used only when a specific implemented proof system supports that technical claim. Selective disclosure formats can significantly reduce data exposure without necessarily being zero-knowledge proof systems.

Institutional value

Selective disclosure can help institutions:

• reduce unnecessary document replication;
• limit sensitive-data concentration;
• align collection with purpose and necessity;
• reduce the impact of a breach;
• provide clearer evidence of what was requested and disclosed;
• build verification workflows that are easier to explain and audit.