This repository contains sources for a feature-rich, FIDO2 CTAP2.1
compatible applet targeting the Javacard Classic system, version 3.0.4. In a
nutshell, this lets you take a smartcard, install an app onto it,
and have it work as a FIDO2 authenticator device with a variety of
features. You can generate and use OpenSSH ecdsa-sk type keys, including
ones you carry with you on the key (-O resident). You can securely unlock
a LUKS encrypted disk with systemd-cryptenroll. You can log in to a Linux
system locally with pam-u2f.
100% of the FIDO2 CTAP2.1 spec is covered, with the exception of features that aren't physically on an ordinary smartcard, such as biometrics or other on-board user verification. The implementation in the default configuration passes the official FIDO certification test suite version 1.7.17 in "CTAP2.1 full feature profile" mode.
In order to run this outside a simulator, you will need a compatible smartcard. Some smartcards which describe themselves as running Javacard 3.0.1 also work - see the detailed requirements.
You might be interested in reading about the security model.
-
Download JavacardKit: Obtain a copy of JavacardKit version 3.0.4 (or jckit_303 if you prefer).
-
Set Environment Variable: Configure the
JC_HOMEenvironment variable to point to your JavacardKit directory.export JC_HOME=<path_to_your_jckit_directory>
-
Run Gradle Build: Execute the following command to build the JavaCard application, which will produce a
.capfile for installation../gradlew buildJavaCard
You have multiple options for testing the JavaCard application:
- Actual Smartcard: You can test on a physical smartcard.
- Virtual SmartCard: Alternatively, you can use VSmartCard and JCardSim for quicker and easier testing.
Simply install the .cap file onto the smartcard and proceed with testing.
- VSmartCard and JCardSim: Use these tools for a simulated environment.
- Third-Party Testing Suites: Utilize tools like SoloKey's
fido2-testsfor comprehensive analysis. TheVSimclass can help you get started.
- Python Test Suite: Navigate to the
python_testsdirectory, which contains Python-language tests. - Run the Tests: Execute the following commands to set up and run the tests.
export JC_HOME=<your_jckit> ./gradlew jar testJar python -m venv venv ./venv/bin/pip install -U -r requirements.txt ./venv/bin/python -m unittest discover -s python_tests
- Interoperability: These tests use the Python
python-fido2library because there is currently no FIDO2 client library for the JVM. You can also test withlibfido2, Python libraries, or the official FIDO Standards Tests (Javascript).
- Fast IPC: By default, the tests use fast interprocess communication with the JVM, bypassing PC/SC. The tests take less than fifteen seconds to run, for me, even though there are almost two hundred cases.
- Customization: You can modify settings in
python_tests/ctap/ctap_test.pyto enable CTAP traffic logging, allow JVM remote debugging, or use a VSmartCard PC/SC connection.
- If you wish to contribute to the project, feel free to raise a pull request or open an issue.
If you just want to install the app, look at what you can configure.
I suggest reading the FAQ and perhaps the security model.
If you're a really detail-oriented person, you might enjoy reading about the implementation.
| Feature | Status |
|---|---|
| CTAP1/U2F | Implemented (see install guide) |
| CTAP2.0 core | Implemented |
| CTAP2.1 core | Implemented |
| Resident keys | Implemented |
| User Presence | User always considered present: one verification only |
| ECDSA (SecP256r1) | Implemented |
| Other crypto, like ed25519 | Not implemented - availability depends on hardware |
| Self attestation | Implemented |
| Basic attestation with ECDSA certs | Implemented (see install guide) |
| Webauthn (NOT CTAP!) uvm extension | Implemented |
| Webauthn devicePubKey extension | Not implemented |
| CTAP2.1 hmac-secret extension | Implemented |
| CTAP2.1 alwaysUv option | Implemented |
| CTAP2.1 credProtect option | Implemented |
| CTAP2.1 PIN Protocol 1 | Implemented |
| CTAP2.1 PIN Protocol 2 | Implemented |
| CTAP2.1 credential management | Implemented |
| CTAP2.1 enterprise attestation | Implemented in code, disabled |
| CTAP2.1 authenticator config | Implemented |
| CTAP2.1 minPinLength extension | Implemented, default max two RPIDs can receive |
| CTAP2.1 credBlob extension | Implemented, discoverable creds only |
| CTAP2.1 largeBlobKey extension | Implemented |
| CTAP2.1 authenticatorLargeBlobs | Implemented, default 1024 bytes storage (max 4k) |
| CTAP2.1 bio-stuff | Not implemented (doesn't make sense in this context?) |
| Key backups | Not implemented |
| APDU chaining | Supported |
| Extended APDUs | Supported |
| Performance | Adequate (sub-3-second common operations) |
| Resource consumption | Reasonably optimized for avoiding flash wear |
| Bugs | Yes |
| Code quality | No |
| Security | Theoretical, but see "bugs" row above |
| Platform | Status |
|---|---|
| Android (Google Play) | CTAP1 only [1] |
| Android (hwsecurity) | Working |
| Android (MicroG) | Working |
| Android (FIDOk) | Working |
| iOS | Reported working |
| Linux (libfido2) | Working |
| Linux (FIDOk) | Working |
| Windows 10 | Working |
| Smartcard | Status |
|---|---|
| J3H145 (NXP JCOP3) | Working |
| J3R180 (NXP JCOP4) | Working |
| OMNI Ring (Infineon SLE78) | Working |
| jCardSim | Working |
| Vivokey FlexSecure (NXP JCOP4) | Working |
| A40CR | Reported Working |
| Application | Status |
|---|---|
| Chrome on Android | CTAP1 Only (Play Services [1]) |
| Chrome on Linux | Working, USBHID only [2] |
| Chrome on Windows | Working |
| Fennec on Android | CTAP1 Only (Play Services [1]) |
| WebView on Android | Working |
| Firefox on Linux | Working, USBHID only [2] |
| Firefox on Windows | Working |
| MS Edge on Windows | Working |
| Safari on iOS | Reported working |
| OpenSSH | Working |
| pam_u2f | Working |
| systemd-cryptenroll | Working |
| python-fido2 | Working |
| FIDOk | Working |
There are two compatibility issues in the table above:
- Google Play Services on Android contains a complete webauthn implementation, but it appears to be hardwired to use only "passkeys". If a site explicitly requests a non-discoverable credential, you will be prompted to use an NFC security key, but this is only CTAP1 and not CTAP2. There's nothing fundamentally preventing this from working on Android but the current state of Chrome and Fennec are that CTAP2 doesn't, because both use the broken Play Services library. MicroG has a fully-working implementation, though! See microg/GmsCore#2194 for PIN support.
- Some browsers support FIDO2 in theory but only allow USB security keys - this implementation is for PC/SC, and doesn't implement USB HID, so it will only work with FIDO2 implementations that can handle e.g. NFC tokens instead of being restricted to USB. In order to use a smartcard in these situations you'll need https://github.com/StarGate01/CTAP-bridge , https://github.com/BryanJacobs/fido2-hid-bridge/ , https://github.com/BryanJacobs/FIDOk/ or similar, bridging USB-HID traffic to PC/SC.