Selective Disclosure

Selective Disclosure is a privacy-enhancing feature of digital credential systems that enables a holder to reveal only specific attributes from a credential when presenting it to a verifier, rather than sharing the entire credential content. This principle is fundamental to the design of the European Digital Identity Wallet under eIDAS 2.0, reflecting the regulation's strong emphasis on data minimisation and user control.

For example, if a wallet holds a driving licence credential containing the holder's name, date of birth, address, licence categories, and photo, selective disclosure allows the holder to present only the licence categories to a car rental company, without revealing their home address or exact date of birth. The ARF specifies two credential formats that support selective disclosure natively: SD-JWT (Selective Disclosure JSON Web Token), which uses salted hashes to allow individual claims to be revealed or withheld; and mdoc (ISO 18013-5), which structures credentials into distinct data elements that can be independently released. Both formats ensure that the verifier can still cryptographically verify the authenticity and integrity of the disclosed attributes, even when other attributes are withheld.

Selective disclosure goes hand in hand with the eIDAS 2.0 requirement that relying parties must request only the attributes that are strictly necessary for the service they provide. The wallet interface will present the user with a clear view of what data is being requested, and the user can approve or decline.

For organisations, supporting selective disclosure is not optional; it is a core architectural requirement. Relying parties must design their attribute requests to be minimal, and their systems must be capable of verifying partially disclosed credentials.