Bitstream encryption misconception?

[timmyathp]

Hi Support,

I think I maybe harboring a misconception with-respect-to bitsream encryption on series-7 devices. I have provisioned my board to inlcude an AES Serial EEPROM and I planned to use the I2C interface for it ... subsequently, I've been completely puzzled as to how connect this EEPROM to the sereis-7 FPGA ... I can't seem to find any dedicated pins for it (e.g. as in the case of dedicated configuration pins) ... so then I tried to find some reference to available Xilinx I/P that would be need to be used in conjunction with an external device (e.g. serial EEPROM) that had dedicated I/O on that I/P module for me to assign a couple of physical pins to ... but I couldn't find anything.

I then had a little "Aha" (or "Doh") ... what if I have completely misunderstood how bitstream encryption works on series-7? ... perhaps the encryption key is stored on the Series-7 device itself and then it would make sense why I need to connect a button cell to VBATT to maintain the encryption key when power is removed ... double-"Doh".

Q: Is an external serial EEPROM required?

Many thanks,
Tim.

[iguo · Accepted solution]

No. An external strorage device is not required.

7 Series has internal BBRAM and EFUSE to store the encryption key. You can choose which one to use according to the requirement.

Read UG470, Chapter 5, 'Bitstream Security‘. It provides details about Xilinx security strategy.

[timmyathp]

Thank you, @iguo