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JavaCard ePurse

This is an implementation of a JavaCard ePurse. It is based on the template shared created by FractalizeR!

The project makes use of the Javacard Development Kit 2.2.1. Building is done using an Ant build script.

Prerequisites

• Java Runtime Environment (JRE) and the Java Development Kit (JDK).
• GlobalPlatformPro (version v0.3.4-29-g15d7427), for accessing the applets on the JavaCard.

Project Setup

1. Install latest Java SDK.

2. Open project using IDEA’s File -> Open project

3. Go to File -> Project Structure -> SDKs and add the SDK you installed in step 1. If there is already something, you can delete it before adding the newly installed SDK.

4. Go to File -> Project Structure -> Libraries. Remove current Classes entry. Then add \lib\jc221\lib\api.jar.

5. Open Common.properties file and setup everything you need there according to the comments. This includes the path to SDK installation folder. Open build.xml (this is an Ant build package so you need Ant plugin to be installed in IDEA) and correct the entries that follow ${APPLETAIDPREFIX} to suit your AID.

6. To build the applet, go to use View -> Tool Windows -> Ant Build. A window will pop up on the right side of your screen. If you don't see any build targets, click on the green plus and select the build.xml file. Use binarize.all.standard to build the applet for Gemalto TOPs and similiar.

7. Target files will be placed in \out\ePurse\javacard

8. If you have more than one applet in the project, edit build.xml and add a second entry under each tag with the info you need.

Now you can build your applet using IDEA's menu: Build -> Build Project

Common Problems

Q: IntelliJ does not autocomplete on the .jar I imported

A: This is probaby because your sources are not specified as sources in the project itself. Go to File -> Project Properties, click on Modules. Now click on the folder that contains your sources (src in our case), and mark the folder as Resources.

Q: When I try to build and run the Terminal module, I get one of the following errors: Cannot start compilation: the outpath path is not specified for module "Terminal". Specify the outpat path in Configure Project or Error: Could not find or load main class Terminal

A: This has something to do with the output path of the module. File -> Project Structure (or CTRL + ALT + SHFT + S for short), select the Terminal module. In the tab Paths, under Compiler ouput select Inherit project compile output path. On the left side, under Project Settings, click on Project. On the bottom, you see Project compiler output. This is the location where .class files of the module will be put. In your project, create an addition folder called classes, and put the absolute location in this field (e.g. C:\Users\%USERNAME%\Documents\ePurse\out\classes, where %USERNAME% is your username). Once done, click Apply on the bottom and you should be good to go.

Installing Applets

To access the applets on the card, put the card in the cardreader and connect the cardreader with the computer. The following commands can now be used (where applet.cap is the applet you want to install):

• List applet

  java -jar gp.jar -list
  

• Install applet

  java -jar gp.jar -install applet.cap
  

• Delete applet. An applet can be deleted by specifying the AID (Application Identifier) of the applet:

  java -jar gp.jar --deletedeps --delete 3B2963616C6300
  

Card errors

Here is a list of the errors the card can throw:

• SW_VERIFICATION_FAILED (0x6300)
• SW_PIN_VERIFICATION_REQUIRED (0x6301)
• SW_TERMINAL_VERIFICATION_FAILED (0x6302)
• SW_CARD_BLOCKED (0x6303)
• SW_WRONG_NONCE (0x6304)
• SW_NO_MORE_PIN_ATTEMPTS (0x6305)

Structure APDU messages

SELECT command

Command APDU:

Response APDU:

Personalisation protocol

3. Publickey and request card

In this part the terminal communicates the public key of the newly created card and requests a key

This consists of the following:

Payload: publickey card || expiration date (in seconds) || implicit request for Id

Response: card id

Verification protocol

In this protocol we verify whether the card and the terminal are still valid

1. VERIFY HI command (T - C)

Command APDU:

Plaintext: nonce Payload is: Plaintext

This is not signed because we don't have the public key of the terminal.

Response APDU:

2. Cid command (C - T)

Command APDU:

Plaintext: nonce Payload is: Plaintext

This is not signed because we don't have the public key of the terminal.

Response APDU:

3. Ta to backend ( T - BE )

We send the received APDU of the card and the one crafted by the terminal to the backend for a verification.

PlaintextA: Nonce || CardId PlaintextB: Nonce+1 || TerminalId Payload: PlaintextA || [PlaintextA]_Signed || PlaintextB || [PlaintextB]_Signed

The backend does some checks and returns the public key of the card and the public key of the terminal, also signed by the backend:

PlaintextResponse = Nonce+2 || public key card (exponent + modulus) || public key terminal (exponent + modulus) PayloadResponse = [PlaintextResponse]_Signed

Decommisioning protocol

2. Request for deletion ( T - BE )

The terminal forwards the decom request signed by the card

Plaintext: Nonce+1 || CardId Payload: [Plaintext]_Signed

Response: [nonce incremented || Implicit OK] signed by the backend, this is forwarded to the smartcard

Reloading protocol

3. Requests balance of a card

The terminal forwards the request of a card to view his balance

Plaintext: Nonce+1 || CardId Payload: [Plaintext]_signed

Response: [Nonce incremented || correct balance ] signed by the backend

Credit protocol

2. Requests balance of card

See in reloading, response is similar

3. Store the payment commitment

In this step the backened receives a commitment of card that it will pay a certain amount.

Plaintext: Nonce || CardId || Amount Payload: [Plaintext]_Signed

Response: [Nonce incremented || Implicit OK] signed by the backend

CREDIT command

Command APDU:

Response APDU:

DEBIT command

Command APDU:

Response APDU:

VERIFY PIN command

Command APDU:

Response APDU: