Attribute: Identity Attribute

An identity attribute is a specific, discrete piece of verified information about a person. In the EUDI Wallet ecosystem, attributes are the individual data points contained within electronic attestations (credentials). Each attestation is composed of one or more attributes that together describe a particular aspect of the holder's identity, qualifications, or status. For example, a national ID attestation contains attributes like family name, given name, date of birth, and nationality, while a driving license attestation contains attributes like license categories, issue date, and expiry date. The power of the EUDI Wallet lies in its ability to let users selectively disclose individual attributes rather than entire documents.

The EUDI Wallet ecosystem organizes attributes into several categories. Identity attributes include the core personal identifiers defined in the Person Identification Data (PID) specification: family name, given name, date of birth, unique personal identifier, and nationality. These attributes are issued by government authorities and carry the highest level of trust within the system.

Derived attributes are computed from base attributes without revealing the underlying data. The most important example is the age-over threshold: instead of disclosing the actual date of birth, the wallet can present a derived attribute confirming that the holder is over a certain age (18, 21, 65, etc.). This is a practical implementation of data minimization that enables common use cases like age verification without unnecessary personal data exposure.

Qualification and status attributes cover professional credentials, educational degrees, health information, and other domain-specific data. A university diploma attestation might contain attributes for institution name, degree title, field of study, graduation date, and grade. A professional license attestation might contain the license type, issuing authority, validity period, and any restrictions. These attributes enable the EUDI Wallet to serve as a complete digital credential holder.

One of the most important innovations in the EUDI Wallet is the ability to selectively disclose individual attributes from an attestation. Traditional identity verification requires showing an entire document, revealing far more information than necessary. When you show your passport at a hotel, the clerk sees your name, birthdate, photo, passport number, nationality, and all other passport data, even though only your name and nationality may be needed.

The EUDI Wallet changes this model through cryptographic selective disclosure. Using SD-JWT (Selective Disclosure JSON Web Tokens) or mdoc (ISO 18013-5) formats, the wallet can present proofs that reveal only the specific attributes requested by the verifier. The remaining attributes are cryptographically hidden but still covered by the issuer's digital signature, ensuring that the disclosed attributes are authentic.

Before any attribute is shared, the EUDI Wallet displays a consent screen to the user showing exactly which attributes the verifier is requesting and why. The user can approve or reject the request, maintaining full control over their personal data. This consent mechanism is a core GDPR compliance feature of the wallet and a key difference from traditional identity systems where data sharing is all-or-nothing.

For attributes to work across borders and between different systems, they must follow standardized schemas that define the attribute names, data types, and semantics. The European Commission has published credential schemas for PID and common attestation types, ensuring that a "family_name" attribute issued in Germany is interpreted identically by a verifier in Spain.

Attribute schemas also handle multilingual challenges. Personal names may use different character sets across EU countries, dates may be formatted differently, and addresses follow country-specific structures. The standardized schemas define how these variations are encoded, ensuring consistent interpretation across the 27 member states and their diverse linguistic traditions.

Schema registries maintained at the EU level publish the authoritative attribute definitions that all credential issuers and verifiers reference. When a new credential type is standardized, such as a European Health Insurance Card attestation, the attribute schema is published in the registry so that issuers across all member states produce compatible credentials that any verifier can process.

• •Family name, given name (PID identity attributes)
• •Date of birth, nationality, address (PID attributes)
• •Age-over-18 (derived boolean attribute for age verification)
• •Driving license categories, degree title, professional license type