NRF9160 Board for Qr Code Project

[Gioele]

I closed the previous discussion by mistake: https://devzone.nordicsemi.com/f/nordic-q-a/83067/nrf9160-board-for-qr-code-project?ReplySortBy=CreatedDate&ReplySortOrder=Ascending

None can read the QR code directly because the QR Code is in a secure anti-tamper location with reliable staff. So we need to make secure the transmission.

How we can see what we are using? We didn't touch anything about the domain of the example so probably we are using the SPM.

These are the logs when we try to execute the uart in non secure domain:

2022-03-08T14:46:31.601Z DEBUG modem << * Booting Zephyr OS build v2.6.99-ncs1-1  *
2022-03-08T14:46:31.604Z DEBUG modem << Flash regionsDomainPermissions
2022-03-08T14:46:31.611Z DEBUG modem << 00 01 0x00000 0x10000 Securerwxl
2022-03-08T14:46:31.612Z DEBUG modem << 02 31 0x10000 0x100000 Non-Securerwxl
2022-03-08T14:46:31.614Z DEBUG modem << Non-secure callable region 0 placed in flash region 1 with size 32.
2022-03-08T14:46:31.616Z DEBUG modem << SRAM regionDomainPermissions
2022-03-08T14:46:31.617Z DEBUG modem << 00 07 0x00000 0x10000 Securerwxl
2022-03-08T14:46:31.619Z DEBUG modem << 08 31 0x10000 0x40000 Non-Securerwxl
2022-03-08T14:46:31.620Z DEBUG modem << PeripheralDomainStatus
2022-03-08T14:46:31.622Z DEBUG modem << 00 NRF_P0               Non-SecureOK
2022-03-08T14:46:31.624Z DEBUG modem << 01 NRF_CLOCK            Non-SecureOK
2022-03-08T14:46:31.625Z DEBUG modem << 02 NRF_RTC0             Non-SecureOK
2022-03-08T14:46:31.626Z DEBUG modem << 03 NRF_RTC1             Non-SecureOK
2022-03-08T14:46:31.628Z DEBUG modem << 04 NRF_NVMC             Non-SecureOK
2022-03-08T14:46:31.629Z DEBUG modem << 05 NRF_UARTE1           Non-SecureOK
2022-03-08T14:46:31.630Z DEBUG modem << 06 NRF_UARTE2           SecureSKIP
2022-03-08T14:46:31.631Z DEBUG modem << 07 NRF_TWIM2            Non-SecureOK
2022-03-08T14:46:31.633Z DEBUG modem << 08 NRF_SPIM3            Non-SecureOK
2022-03-08T14:46:31.634Z DEBUG modem << 09 NRF_TIMER0           Non-SecureOK
2022-03-08T14:46:31.635Z DEBUG modem << 10 NRF_TIMER1           Non-SecureOK
2022-03-08T14:46:31.636Z DEBUG modem << 11 NRF_TIMER2           Non-SecureOK
2022-03-08T14:46:31.637Z DEBUG modem << 12 NRF_SAADC            Non-SecureOK
2022-03-08T14:46:31.639Z DEBUG modem << 13 NRF_PWM0             Non-SecureOK
2022-03-08T14:46:31.640Z DEBUG modem << 14 NRF_PWM1             Non-SecureOK
2022-03-08T14:46:31.641Z DEBUG modem << 15 NRF_PWM2             Non-SecureOK
2022-03-08T14:46:31.667Z DEBUG modem << 16 NRF_PWM3             Non-SecureOK
2022-03-08T14:46:31.670Z DEBUG modem << 17 NRF_WDT              Non-SecureOK
2022-03-08T14:46:31.672Z DEBUG modem << 18 NRF_IPC              Non-SecureOK
2022-03-08T14:46:31.674Z DEBUG modem << 19 NRF_VMC              Non-SecureOK
2022-03-08T14:46:31.677Z DEBUG modem << 20 NRF_FPU              Non-SecureOK
2022-03-08T14:46:31.681Z DEBUG modem << 21 NRF_EGU1             Non-SecureOK
2022-03-08T14:46:31.684Z DEBUG modem << 22 NRF_EGU2             Non-SecureOK
2022-03-08T14:46:31.686Z DEBUG modem << 23 NRF_DPPIC            Non-SecureOK
2022-03-08T14:46:31.688Z DEBUG modem << 24 NRF_REGULATORS       Non-SecureOK
2022-03-08T14:46:31.689Z DEBUG modem << 25 NRF_PDM              Non-SecureOK
2022-03-08T14:46:31.692Z DEBUG modem << 26 NRF_I2S              Non-SecureOK
2022-03-08T14:46:31.694Z DEBUG modem << 27 NRF_GPIOTE1          Non-SecureOK
2022-03-08T14:46:31.695Z DEBUG modem << SPM: NS image at 0x10000
2022-03-08T14:46:31.697Z DEBUG modem << SPM: NS MSP at 0x20018af8
2022-03-08T14:46:31.698Z DEBUG modem << SPM: NS reset vector at 0x16d81
2022-03-08T14:46:31.700Z DEBUG modem << SPM: prepare to jump to Non-Secure image.
2022-03-08T14:46:31.702Z DEBUG modem << * Booting Zephyr OS build v2.6.99-ncs1-1  *

We are reading from the UART using exactly the lpuart of the example online (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.7.1/nrf/samples/peripheral/lpuart/README.html) and we think that the data from the QR code scanner are stored like a string.

[Gioele]

Didrik Rokhaug said:

The requirement also doesn't make sense, because running something in the secure domain doesn't magically make anything "safe" or "secure". It is the sepparation between the domains that are important.

So what is your advice? Of course, we need to merge the code in the non-secure domain, and then how can we make this code untouchable? Our project must be tamper-proof. No one should modify our code, no one should modify our data.

strcpy(totalQrCode, evt->data.rx_buf.buf);
printk("First code %s\n", totalQrCode);

With these two lines of code, I print the data of the buffer. But with this method, I print not only the last data read but also the data previously read plus some strange characters. I made some strange operations with the strings to make the right code but I am sure that this isn't the right way to work.

[Didrik Rokhaug]

Gioele said:

Fullscreen

strcpy (and any standard functions that works on string) assumes that the string is 0 terminated. So strcpy will keep copying unitl it reaches a byte that is 0. That means that if your data isn't 0 terminated, you will copy too much.

A better way to do the copy would be to check how many bytes were read, and only copy that amount (and possibly adding 0 termination to the data, so it can be treated as a string later).

Gioele said:

So what is your advice? Of course, we need to merge the code in the non-secure domain, and then how can we make this code untouchable? Our project must be tamper-proof. No one should modify our code, no one should modify our data

Having (part of) your application in the secure domain wouldn't keep anyone with physical access to the device from being able to extract your application by its own anyway.

For that, you need to disable debug access, etc.

See https://infocenter.nordicsemi.com/topic/ps_nrf9160/uicr.html and https://infocenter.nordicsemi.com/topic/ps_nrf9160/chapters/dif/ctrl-ap.html for more information.

When it comes to choosing between the different security mechanisms, it is important to know what you are trying to protect and what you are trying to protect it from.

[Gioele]

Ok perfect.

evt->data.rx_buf.buf 

I need to clean this buffer of the lpuart example because each time that I read something new it is added to the buffer and when its memory is full I have some problems.

I want that the code is open to changes for only the developers and that the data stored are not modified (and possibly also not read) from malicious people.

[Didrik Rokhaug]

Gioele said:

Ok perfect.

Fullscreen

Have you read the documentation for the async UART API?

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/zephyr/reference/peripherals/uart.html#c.uart_event_type

[Gioele]

Perfect!