Read a key from secure NVM

[shravani]

Hi, I wanted to read a key from secure NVM, is it possible to read back a key? I want to use this key further in my application. I checked the RTD firmware there is only one service for exporting key from RAM. Also, in the Firmware reference manual of HSE it is mentioned that SHE NVM keys cannot be exported. How could I use stored key in my application?

Please check below details.

1) Microcontroller: S32K312_100MQFP

2) IDE: S32DS 3.5  

3) SDK Version: PlatformSDK_S32K3_2022_03

[HaiHoangSoftware]

Hi,

I can not read AES key after import. I'm using NVM key handle.

Importing key is success. But export key is failed.

Is there anyone know how to solve this issue?

Thanks a lot.

Here is my implementation:

hseKeyInfo_t keyInfo = {0};
uint8_t sharedSecret[448];
uint16_t sharedSecretLen = 32;
void testFunction(void) {
hseSrvResponse_t hseResponse = HSE_SRV_RSP_GENERAL_ERROR;
hseResponse = ExportPlainSymKeyReq( EXAMPLE_NVM_KEY_HANDLE,
&keyInfo, sharedSecret, &sharedSecretLen);
}

[davidtosenovjan]

It is stated in section
6.3.6.2 SHE key update policies

"When RAM_KEY is updated with the SHE key update protocol, it cannot be exported, until it is updated in plain via the key import service or via the SHE plain key update."

"NVM SHE keys cannot be exported." as you already screenshot.

[shravani]

Hi, I want to apply AES 128 encryption on the key which is stored in the secure NVM. How could I achieve this?

[davidtosenovjan]

It cannot be done as a key stored in the secure NVM cannot be exported.