CC1310: Hardware random generator

Viki Shi

Part Number: CC1310

Hi Team,

Is there any problem if call myCOM_generateRandomBytes() every second in software? A customer needed to get random number every second and the program crashed [UART crashed too]. And this problem did not appear when online emulating, but easily occurred when single chip running.

Please check his code below:

/* Generate random bytes in the provided buffer up to size using the TRNG */
void myCOM_generateRandomBytes(void) {
    
    int_fast16_t result;
    // if (canTrigTrng)
    // {
    //     return;
    // }
    // canTrigTrng = true;
    /* Generate some randomness in the provided buffer */
    // if (handleTrng)
    {
        result = TRNG_generateEntropy(handleTrng, &entropyKey);
        if (result != TRNG_STATUS_SUCCESS) {
            TRNG_close(handleTrng);
            handleTrng = TRNG_open(Board_TRNG0, &paramTrng);
            if (!handleTrng) {
                while (1)
                    ;
            }
        }
    }
    

    // TRNG_close(handleTrng);
}
void init_generateRandom(uint8_t size)
{
    
    TRNG_init();
    CryptoKeyPlaintext_initBlankKey(&entropyKey, keyLocationBuffer, size);

    TRNG_Params_init(&paramTrng);
    paramTrng.returnBehavior = TRNG_RETURN_BEHAVIOR_CALLBACK;
    paramTrng.callbackFxn = trng_callback;
    paramTrng.timeout = SemaphoreP_WAIT_FOREVER;
    /* Open a TRNG_Handle with default parameters */
    handleTrng = TRNG_open(Board_TRNG0, &paramTrng);
    if (!handleTrng) {
        while (1)
            ;
    }
    myCOM_generateRandomBytes();
}

BR,

Viki Shi

over 4 years ago

0 IUsedToBeARealPerson (M-W) over 4 years ago

TI__Guru 58425 points

Hi Viki,

Have you tried using ROV to find out why the program crash? Like do you get an exception or are you stuck in a while loop somewhere else?

0 Viki Shi over 4 years ago in reply to IUsedToBeARealPerson (M-W)

TI__Expert 3130 points

Hi,

I will let him try ROV, thanks for the suggestion.

Anyway, he did more tests on multiple modules with the same program. And some of these modules crashed. The suspicious stuck place is TRNG_generateEntropy(handleTrng, &entropyKey). If called TRNG_generateEntropy(handleTrng, &entropyKey) after TX, the problem would occur. If called before TX, the issue could be improved a lot, only crashed in rare case.

So where did the seed of hardware random generator come from? And what factor will impact its generation?

BR,

Viki Shi