- Rebel Simcard Scanner
Rebel Simcard Scanner¶
The Rebel Simcard folks are selling a relatively inexpensive device for generating SIM card traces as Simcard Scanner.
The Scanner has one small plug-in SIM sized slot and one full-size (ISO 7816-1) slot for your actual simcard.
It also has a small socket for a FPC cable that goes to a small PCB in the size of a plug-in sim.
You put the FPC-attached PCB into your phone (instead of the SIM card) and put the actual SIM inside the Scanner.
Furthermore, you connect it via the USB-B connector to your PC.
The I/O line of the SIM card is wired to the RxD pin (5) of the FT232RL on the Scanner. Unfortunately, the CLK
line is not connected, and neither can the device serve as a proxy between SIM and phone.
It's possible to use it as smart card physical interface for SIMtrace.Here the pinout :
Mode of operation¶
Original UART use¶
The original RebelSIM users simply use the FT232RL in UART mode and set the baud rate to match that of the actual SIM
card reader. Since the baudrate is negotiated in the PPS after ATR, and it depends on the frequency of the CLK signal
generated by the reader.
This means you effectively have to use an oscilloscope to measure the bit length (etu) and calculate a matching baud
rate which you can then program the FT232R to use.
Modified bit-banging use¶
By using the FT232 asynchronous bit-banging mode, it is possible to obtain samples of the I/O line, decoding
the actual T=0 (or with some SIM cards + phones T=1) protocol.
The unresolved problem with this is that the sample clock of the FT232R seems very unstable. This results in
a lot of jitter in the sample stream. Furthermore it is suspected that USB may cause buffer overruns and leads to
Harald has been doing a lot of experimentation with this, and unfortunately abandonded the project for now.