Credit Card Checker

Introduction

Did you ever encounter trouble with your credit card in remote places? Didn't your credit card work while shopping during a flight? One reason could be that your card is not "offline capable". 

This app helps you to understand the capabilities, limitations, security settings of your credit or debit card by reading the contactless chip and simulating a transaction.  

Android App

You can find the Android app in Google Play Store:

 https://play.google.com/store/apps/details?id=de.erichambuch.apps.creditcardchecker 

Supported USB Card Readers

Per default the app uses the build-in EMV/contactless reader in your smartphone. To read the ICC an experimental option is available to connect an external card reader via USB port. This requires a reader and a card that supports the T=0 or T=1 protocol with automatic voltage/baud settings.

The following readers have been tested:

• SCM SCR 3310

• OmniKey 3121 (only by setting protocol to T=0 in the settings)

• ReinerSCT CyberJack standard (limited to certain cards, not recommended)

The following readers are known NOT to be working properly:

• see the List provided on https://ccid.apdu.fr/ccid/unsupported.html 

Please feel free to give me any feedback. Please send me the protocol of the reader output via email.

Known issues

Some cards contain several application (e.g. German Girocards up to five!), therefore reading may cause a timeout. In that case, open the settings and switch off or try the settings:

• Select Application: choose a specific application where you want the details

• Get Processing Options command: try to switch off this option first, then try the previous setting for a dedicated application

• Read Counters and Read Log Entries: switch off these options

Permissions

The following permissions are needed by the app:

• NFC (required) - connection to the Near-Field-Communication interface to read the card with your smartphone

• USB (optional) - if a smartcard reader is connected via USB port

• CAMERA (optional) - to take a snapshot of a receipt to automatically analyze

• INTERNET (optional) - only required to load OCR components for text recognization of using the function aforementioned

Helpful external links

The following links may be helpful. Please use them at your own risk, as I do not check the links regularly and are not responsible for the content:

• https://emv.smart-upstart.de/index.php?title=Spezial:Alle_Seiten

• https://www.spotterswiki.com/emv/ 

• http://pannetrat.com/Cardpeek/ 

• https://github.com/LudovicRousseau/CCID/ 

• https://emvrace.github.io/ 

Last update: 07th Apr 2024