Selective Disclosure Explained: How to Minimize Data Exposure with EUDI

The All-or-Nothing Problem

Historically, digital identity has been an "all-or-nothing" deal.

• You show your physical ID card to a bouncer to prove you are 18. They see your name, your address, your exact birth date, and your passport number.

• You upload a utility bill to verify your address. The company sees your usage details and account number.

This "data leakage" is dangerous. It spreads PII (Personally Identifiable Information) everywhere, increasing the risk of identity theft.

Enter Selective Disclosure

Selective Disclosure is the ability to share only the specific data points (claims) required for a transaction, and nothing else.

In the EUDI Wallet ecosystem, this is a core feature. It transforms the ID card from a static image into a database of separate, verifiable facts.

How It Works (The User View)

1. Request: A car rental site asks for your Driving License Class and Last Name.

2. Consent: Your wallet pops up. It says: "CarRental Co wants to see your License Class and Name. Your Address and Date of Birth will remain hidden."

3. Action: You approve. The rental company receives only those two fields.

The Technical Magic (SD-JWT & mdoc)

Under the hood, this relies on advanced cryptography.

• SD-JWT (Selective Disclosure JSON Web Token): The issuer signs the user's data in a way that allows the user to "blind" or remove specific fields before sending the token to the verifier, without breaking the issuer's signature.

• mdoc (ISO 18013-5): Uses a similar concept where data elements are individually signed or secured, allowing the device to release only requested elements.

Why It Matters for Business

1. Radical GDPR Compliance

GDPR mandates Data Minimization (Article 5(1)(c)). You should only collect data that is "adequate, relevant and limited to what is necessary." Selective disclosure makes this easy. You can't accidentally store data you never requested.

2. Reduced Liability

If you don't hold the user's home address, you can't lose it in a breach. Minimizing your data footprint lowers your cybersecurity risk profile.

3. User Trust

Users are becoming privacy-savvy. An app that asks for "Full Access" is suspicious. An app that asks only for "Verification of Age" feels respectful and modern. As people’s awareness grow, the needs for this will grow too.

Implementation Tips

• Audit your forms: Go through every field you ask for during onboarding. Do you really need it? If not, remove it from your request scope.

• Explain the benefit: Tell users, "We use EUDI Wallet so you don't have to share your address with us." Make privacy a feature of yours.

Building with Authbound

Authbound's verification platform natively supports selective disclosure.

• Granular Scopes: Define exactly which attributes you need (e.g., family_name, age_over_18).

• Privacy by Default: Our SDKs are designed to request the minimum viable dataset.

Privacy isn't just about hiding; it's about control. Selective disclosure gives that control back to the user, and smart businesses will embrace it.

Minimize your risk.

Contact us at [email protected] or through authbound.io/book-a-meeting