Chapter 2 · 5/8
Two formats: SD-JWT VC and mdoc
One credential in two formats: SD-JWT VC for the internet, mdoc for in person. Why both?
4 min
Even when a credential's content stays the same, how it is packaged matters. You can send a letter by e-mail or by courier: same letter, different envelope. Digital credentials have two common "envelopes", and Tamga uses both.
SD-JWT VC: for the internet
The IETF credential format: JSON-based, with fields that can be revealed one by one (selective disclosure). is a credential written in the language of the web. It is JSON-based, so sites, apps and servers read it easily. The "SD" stands for selective disclosure: each field is sealed separately, and the person opens only the fields requested. "Sign in with Tamga", an online application or an in-app age check all use this format.
mdoc: for in person
The ISO/IEC 18013-5 credential format, designed for mobile driving licences and shown in person over QR and Bluetooth. is an international standard designed for mobile driving licences (ISO/IEC 18013-5). It uses a compact binary encoding and is built for in-person situations, even without internet: a concert gate, a hotel front desk, a counter. Browsers' new digital credentials interface supports it too.
Why both?
Because credentials are used in two different worlds. Online, flexibility and web compatibility matter; in person, speed and offline operation. The EU digital identity framework requires both formats as well. Tamga therefore issues the identity credential in both formats at once; other credential types use one or both as needed.
Summary
- SD-JWT VC is for the internet: JSON-based, field-by-field disclosure.
- mdoc is for in person: ISO/IEC 18013-5, QR and Bluetooth, offline.
- The rules are the same in both; the EU requires both as well.
Go deeper
Technical details and binding rules: