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Identity Credential

Project Description

Libraries and reference applications for working with real-world identity.

The initial focus for this work was mdoc/mDL according to ISO/IEC 18013-5:2021 and related standards (mainly ISO 23220 series and ISO 18013-7) on Android. Current focus includes other credential formats and operating environments.


The project includes two libraries written in Java and Kotlin. The first is identity which provides the core building blocks and which can also be used on server-side environments. The other is identity-android which provides Android-specific extensions to the former. It is designed to run on Android (API 24 or later) and will take advantage of Android-specific features including hardware-backed Keystore, NFC, Bluetooth Low Energy, and so on.

The libraries are intended to be used by Wallet Applications (mobile applications on the credential holder's device), Reader Applications (applications operated on device controlled by the verifier), and Issuance Systems (applications operated by the credential issuer or their agent). They provide the following building blocks

  • A light-weight Secure Area abstraction for hardware-backed keystore
    • Applications can create hardware-backed Elliptic Curve Cryptography keys which can be used for creating Signatures or performing Key Agreement. Each key will have an attestation which can be used to prove to Relying Parties (such as a credential issuer) that the private part of the key only exists in a Secure Area.
    • The identity-android library includes an implementation based on Android Keystore with support for requiring user authentication (biometric or lock-screen knowledge factor, e.g. system PIN) for unlocking the key and also can use StrongBox if available on the device. This is appropriate to use in Android applications implementing ISO/IEC 18013-5:2021 for storing DeviceKey.
    • The identity library includes an implementation backed by BouncyCastle with support for passphrase-protected keys. This isn't suitable for use in Mobile Applications as its not backed by Secure Hardware.
    • Applications can supply their own Secure Area implementations for e.g. externally attached dongles, cloud based HSMs, or whatever the issuer deems appropriate to protect key material associated with their credential.
  • A Credential Store for storage of one or more Credentials
    • Each Credential has a Credential Key which can be used by the issuer to bind a credential to a specific device which is useful when issuing updates or refreshing a credential.
    • Additionally, each Credential has one or more Authentication Keys which can be endorsed by the issuer and used at presentation time.
    • Finally, namespaced data and arbitrary key/value pairs can be stored in a Credential which can be used for credential data and claims. This data is stored encrypted at rest.
  • Data structures and code for provisioning of mdoc/mDLs
    • This code can can be used both on the device and issuer side. No networking protocol is defined, the application has to define its own.
  • Parsers and generators for all data structures used in ISO/IEC 18013-5:2021 presentations, including DeviceResponse, DeviceRequest, MobileSecurityObject and many other CBOR data structures.
  • An implementation of the ISO/IEC 18013-5:2021 presentation flows including QR engagement, NFC engagement (both static and negotiated), device retrieval (BLE, Wifi Aware, and NFC)

Wallet and Reader Android applications

This repository also contains two Android applications using this library in the appholder and appverifier modules. The Wallet application is a simple self-contained application which allows creating a number of mdoc credentials using four different mdoc Document Types:

  • org.iso.18013.5.1.mDL: Mobile Driving License
  • org.micov.1: mdoc for eHealth (link)
  • nl.rdw.mekb.1: mdoc for Vehicle Registration (link)
  • mdoc for Personal Identification

and their associated mdoc name spaces. The first one is defined in ISO/IEC 18013-5:2021 and the other three have been used at mdoc/mDL test events organized by participants of the ISO/IEC JTC1 SC17 WG10 working group.

ISO 18013-7 Reader Website

The wwwverifier module contains the source code for a website acting as an mdoc reader according to the latest ISO 18013-7 working draft (as of Sep 2023) and it's implementing the so-called REST API. There is currently a test instance of this application available at The Wallet Android application also has support for the REST API and registers on Android for the mdoc:// URI scheme. This can be tested end-to-end by going to the reader website (URL above) and clicking on one of the "Request" buttons, and then hitting the mdoc:// link presented on the site. This will cause the browser to invoke the Wallet app which will then connect to the reader and send the credential after user consent.

Source Repositories

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