Functions of Java Card Applet

Select method

The select method tells the JCRE if the applet is ready to process requests, by returning a true value. If the applet is not ready to accept processing requests, the select method returns a false value.

Deselect method

If an applet is selected and you want to select an applet with a different AID, the JCRE calls the currently selected applet’s deselect method.

Process method

Once an applet is selected all communications between the applet and the client application are sent to the process method

This method accepts an APDU object as a parameter. The APDU is sent from the client application to the java card applet, the client application then waits for a response APDU in return. For security reasons references to an APDU object are only allowed within a method, so an APDU must be passed in as a parameter to the method or stored in a local variable. This is to protect against the possibility of one Java Card applet accessing APDU data that belongs to another Java Card applet.

Other specific methods

Writing Data

  • setPersonalData()
  • setPublicPrivateKeys()
  • setBiometrics() – If needed

Reading Data

  • verifyPin()
  • validateSignature()

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