topic Re: [Security] D-Flash CSE driver encryption/decryption interface limitations in S32K

[Security] D-Flash CSE driver encryption/decryption interface limitations

Gideon — Wed, 17 Apr 2024 06:47:45 GMT

Dear NXPs：

Bootloader- D-Flash-32K

Are there any restrictions if I call CSEC_DRV_EncryptCBC/CSEC_DRV_DecryptCBC interfaces of the CSEc driver on D-Flash?

Re: [Security] D-Flash CSE driver encryption/decryption interface limitations

lukaszadrapa — Fri, 19 Apr 2024 15:34:08 GMT

If we are talking about CSEc commands CMD_ENC_CBC and CMD_DEC_CBC, there are no limitations because it is up to software to load plain/encrypted data to CSEc via PRAM interface and then read encrypted/plain data from PRAM. So, software can read the data from anywhere. Mentioned SDK function do not check the addresses, so it can read the data from whole memory map. Just the output buffer needs to be in RAM, of course, so the driver can write the result to the buffer.

Regards,

Lukas

Re: [Security] D-Flash CSE driver encryption/decryption interface limitations

Gideon — Thu, 02 May 2024 02:00:29 GMT

Dear lukaszadrapa：
@lukaszadrapa
NXP S32K142 executes CSEC_CMD_ENC_CBC command in D-Flash, but PUBWEAK HardFault_Handler occurs
SECTION .text:CODE:REORDER:NOROOT(1)
HardFault_Handler
B. Error. There is no problem with IAR Debug single-step execution, but the above HardFault will occur when F5 is executed at full speed, which is very strange.

Re: [Security] D-Flash CSE driver encryption/decryption interface limitations

lukaszadrapa — Fri, 03 May 2024 05:03:00 GMT

Hi @Gideon

not sure what's going on.

First step - did you try to disable interrupts? Second step - you can try to find out what is the reason of the fault exactly:

https://community.nxp.com/t5/S32K-Knowledge-Base/Fault-handling-on-S32K14x/ta-p/1114447

https://www.nxp.com/docs/en/application-note/AN12201.pdf

Regards,

Lukas

Re: [Security] D-Flash CSE driver encryption/decryption interface limitations

Gideon — Thu, 16 May 2024 00:59:44 GMT

Dear lukaszadrapa：
@lukaszadrapa

A1:Disabling interrupts has no effect.The interface I use is

INT_SYS_DisableIRQGlobal();

INT_SYS_EnableIRQGlobal();

A2: IBUSSERR

By the way Viewed the manual S32K-RM.pdf Table 37-7. Allowed simultaneous memory operations,

There are limitations in operating CSE PRAM on D-Flash，Could IBUSSERR be related to this?

Re: [Security] D-Flash CSE driver encryption/decryption interface limitations

lukaszadrapa — Wed, 15 May 2024 07:47:15 GMT

I haven't met this use-case yet but I can see in the manual that you are right. It explicitly says:

If your code is running from data flash, solution is to put the function to RAM memory.