SilentID: Implementing Secure PII Exchange via the EU Digital Identity Wallet
By Bruno Correia • January 2026
Executive Summary: Modern retail still relies on insecure verbal disclosure of PII (Tax IDs, Emails). This paper introduces SilentID, a retail-focused implementation framework that extends the EU Digital Identity Wallet (eIDAS 2.0) to physical stores. It enables encrypted, biometric-verified data transfer at the Point of Sale, solving the privacy and efficiency gaps in current commerce.
1. The Problem: Verbal Data Leakage
In jurisdictions like Portugal, providing a Tax ID (NIF) at the checkout is common. However, the current method—speaking the number out loud—is a security relic. It exposes sensitive data to bystanders and introduces human error that delays transactions and breaks data integrity.
1.1. Privacy & Security Risks
When a customer verbally dictates their phone number or Tax ID to a cashier:
Public Exposure: Bystanders in the queue can easily overhear sensitive data.
Bad Actors: Unscrupulous employees or nearby customers can record this information for identity theft, phishing scams, or harassment.
Lack of Consent Trails: There is rarely a verifiable record of exactly what data was shared and for what specific purpose.
1.2. Operational Inefficiency
Manual entry—whether typed by the cashier or the customer via a PIN pad—is slow. It increases checkout times, frustrates customers, and reduces the throughput of the business.
1.3. Data Integrity
Verbal communication is prone to error. Typos in email addresses lead to lost invoices, and errors in Tax IDs can result in fiscal non-compliance for the consumer.
2. The Solution: SilentID Protocol
SilentID is a standardized digital handshake that leverages the existing EU Wallet ecosystem. Instead of a customer "telling" their data, the store and phone perform a secure exchange.
How it Works
Request: The POS generates a dynamic QR code requesting specific data (e.g., NIF + Email).
Handshake: The customer scans the code with their EU-compliant Identity App. This establishes a secure session using modern encryption standards.
Consent: The user sees exactly what is being shared and approves it via FaceID or Fingerprint.
Silent Transfer: The data is transmitted directly to the POS system via a secure local channel (NFC or BLE), ensuring privacy even without internet access.
3. Comparative Analysis
Current Flow (Legacy)
Customer: "My NIF is 2-4-5-..." (Spoken aloud in a crowded queue).
Result: Risk of identity theft, slow checkout, and potential typos.
SilentID Flow (Proposed)
Customer: Scans screen and taps 'Approve' on their phone.
Result: Encrypted, 100% accurate, and finished in seconds.
4. Alignment with eIDAS 2.0
By positioning SilentID as a retail extension of the European Digital Identity Framework, we leverage existing legal protections:
Biometric Security: Uses the hardware-level security already present in modern smartphones.
Selective Disclosure: Only the requested attributes (like the NIF) are shared, keeping the rest of the ID private.
Interoperability: A tourist from Germany can use their home-country wallet at a Portuguese retailer.