Emulating CID of SD-Card as MITM

Other Hardware Storage
1

Hello,
i am looking for a way to spoof the CID part of an SD Card with different, sepcific data. Therefore i thought to place an Arduino "in-band" to the SD card an the device slot. Traffic should pass through, expect of the SEND_CID command (CMD10).

For know i know that an Arduino can't handle the high datarates of SD traffic itself, but the initialization phase, and hopefully the above cmd also, are done much slower (400 khz?!).

So, i can build a repeater, but had to build some kind of digital switch and listen to the MOSI line until i see the request. As soon as i detect it, i need to "cut" the MISO line, so it is connected to my Arduino instead of the SD card. Then i send my own CID to the host. To know when to switch back to bypassmode, i think i had to gather SD card output also until it fully send its answer. Think i had to delay my output until SD is done.

Do you folks think this is possible at all?

2

How do you know that the Arduino isn't fast enough?

Given that most SD cards are going to be moving megabytes per second I suspect that a 16MHz Arduino isn't actually fast enough so I would start experimenting with a Teensy, since I have many of them available to me.

Remember that a fast SD interface is not using the SPI protocol. It's using all the pins on the card and it won't be obeying simple rules like MOSI and CS.