SCAT

About SCAT

The SCAT app is allowing to communicate with the contactless smart cards, do some cryptographic operation and download the cap file on java cards. It is the conceptual product and has some potential ways to extend the functionality.
System is based on use of the mobile device with NFC capability(debugged on Samsung Galaxy Grand Prime) and smart cards (NXP JCOP 41/JCOP 31, Mifare DESFire EV1(APDU Native Wrapped), Mifare Ultralight).

- After running the application, the splash interface is displayed for a short period of time, and then will be open the license page. After accepting the agreement the Main app tab page named APDU will be open. This UI allow to send data on card and get the response from the card. Each APDU command can have the name and up to 10 last commands can be memorized and retrieved later if needed. Before start communication with a card we must tap the card on the back of the mobile device with NFC enabled. The connection indicator located in the upper-left corner of the interface supposed to show connection status(connected /disconnected).

-The second tab page is named Data. It's just the text edit control for creating and editing some binary/text data for sending on card or create log and save it on the device(/storage/Documents)as a .txt file. By default the device has already file DataFile.txt which can be used.

-The third tab page is named Crypto. This page allow to use following cryptographic algorithms: DES, 3DES2(triple DES with two DES keys), AES-128, AES-192, AES-256. The resulting data can be converted to string without empty space and save/past to APDU data. The spinner named #Key can allow selection of the key by the ID and use it in crypto operations.

-The last tab page is named LOADING and allow to load the .cap file on java card(dual interface). This app has been tested with NXP JCOP41 card.
For the testing purposes the app has default file testproject.cap. It is simple applet which has just 5 instructions(A4-select, B0-read binary, D6-update binary, 20-verify PIN (default: 01 01 01 01 01 01 01 01) and AC-PIN change).
To use different cap file needs to email it in your address and save on the device(Galaxy Grand Prime\Phone\Download). This interface will create and use key set shown in the KEY SETTINGS interface in the "Current 3DES2 keys set". If user needs to change the key on the card, the new key will be shown in "New 3DES2 keys set".

Before using interfaces demanding some key, we have to set all keys used in app by the help of the KEY SETTINS interface(button KEY SETTINGS on the menu bar). This keys will be used on the APDU, CRYPTO and the LOADING tab pages. By default the app has binary key named DEF(40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F) and default key set DEF which combine 3 separate DEF keys. To create a single key, needs to fill in Key ID, Length, CID(optional). The Key Value can be filled manually or by click the button Generate. If everything was successful, click button Save. Successfully created items will be saved on the SQLite DB. The message will confirm the creation of the item record. Then it can be seen in the key list and used by ID for creating key sets used for load the cap file on java card.