LAYR Javacard Access Control Protocol

This repository contains the Java Card applets that are used for the first iteration of our open-source chip design competition, which is about the creation of an ASIC to be deployed in an electronic door lock.

The following variants are included:

• IdentificationApplet: Implements a basic unauthenticated and unencrypted protocol that simply returns a programmable ID. This is intended to be used for the lowest challenge level only.

• AuthenticatedIdentificationApplet: Implements a challenge-response protocol with mutual authentication and key agreement based on AES-128. This is intended to be used for all advanced challenge levels.

Contact and Support

Please contact Niklas Höher (niklas.hoeher@rub.de) if you have any questions, comments, or if you found a bug that should be corrected.

Identification Applet

Simply return the card identifier upon receiving a corresponding request without any authentication or encryption.

Protocol / Command Summary

Command	CLA	INS	Description
GET_ID	0x80	0x12	Returns the unencrypted 16-byte card ID.

For an example sequence, execute the included protocol flow test case.

Authenticated Identification Applet

Overview

Both parties have knowledge over a long-term shared AES-128 key. This key is used to perform mutual authentication and key agreement via a challenge-response protocol to derive an ephemeral AES-128 session key which is then used to encrypt the exchanged data, which mainly correspond to the ID of the card.

• AES Mode: AES-128 ECB, no padding

Protocol / Command Summary

Command	CLA	INS	Description
AUTH_INIT	0x80	0x10	Card generates random 8-byte challenge rc, computes AES_psk(rc || 00..00) using the pre-shared key and returns the ciphertext.
AUTH	0x80	0x11	Terminal decrypts the ciphertext to recover rc, generates its own 8-byte challenge rt, and proves possesion of the key to the card by returning AES_psk(rt || rc) using the pre-shared key.
GET_ID	0x80	0x12	Card and terminal derive an ephemeral AES session key as k_eph = rc || rt and the card returns the 16-byte card ID encrypted using that key if authentication was successful.

For an example sequence, execute the included protocol flow test case.

Building

To compile the applets yourself, run the buildJavaCard gradle task:

./gradlew buildJavaCard --info --rerun-tasks

The resulting .cap file (contains both applets) will be located in ./applet/build/javacard/.

Running Tests

To execute all available tests for both applets, execute the following command:

./gradlew test --info --rerun-tasks

Within the corresponding test classes (IdentificationAppletTest and AuthenticatedIdentificationAppletTest), you can also change the CARD_TYPE variable to execute tests on a physically connected smart card instead of in the simulator.

Output:

> Task :applet:test

AuthenticatedIdentificationAppletTest > testCorrectProtocolFlow() PASSED

IdentificationAppletTest > testCorrectProtocolFlow() PASSED

Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.8/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.

BUILD SUCCESSFUL in 745ms
4 actionable tasks: 1 executed, 3 up-to-date

Installation on a Physical Card

To flash the applets onto a physical card, you need the GlobalPlatformPro utility. Follow the provided installation instructions and execute the following commands:

# Remove old versions of the applets (not required upon initial installation)
gp -uninstall ocdcpro.cap
# Load the .cap file containing both applets onto the card
gp -load ocdcpro.cap
# Install the IdentificationApplet with applet ID "F000000CDC00" and ID "00000000000000000000000000000001"
gp -cap ocdcpro.cap -create F000000CDC00 --applet F000000CDC00  --params 00000000000000000000000000000001
# Install the AuthenticatedIdentificationApplet with applet ID "F000000CDC01", pre-shared AES key "00112233445566778899AABBCCDDEEFF", and ID "00000000000000000000000000000001" 
gp -cap ocdcpro.cap -create F000000CDC01 --applet F000000CDC01  --params 00112233445566778899AABBCCDDEEFF00000000000000000000000000000001

Acknowledgements

This project is based on the Java Card Gradle Template by ph4r05.