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Improvements to the STM32L4 random generation code for improved performance and error handling. Added new WOLFSSL_STM32_RNG_NOLIB define to support generic STM32 series RNG without external ST library.

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This commit is contained in:
David Garske 2019-01-17 09:57:26 -08:00
parent f824c8c769
commit dad88b4c81
1 changed files with 25 additions and 8 deletions
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33
wolfcrypt/src/random.c
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@ -1741,30 +1741,47 @@ int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
#elif defined(STM32_RNG)
/* Generate a RNG seed using the hardware random number generator
* on the STM32F2/F4/F7. */
* on the STM32F2/F4/F7/L4. */
#ifdef WOLFSSL_STM32_CUBEMX
int wc_GenerateSeed(OS_Seed* os, byte* output, word32 sz)
{
RNG_HandleTypeDef hrng;
int i;
word32 i = 0;
(void)os;
/* enable RNG clock source */
__HAL_RCC_RNG_CLK_ENABLE();
/* enable RNG peripheral */
XMEMSET(&hrng, 0, sizeof(hrng));
hrng.Instance = RNG;
HAL_RNG_Init(&hrng);
for (i = 0; i < (int)sz; i++) {
/* get value */
output[i] = (byte)HAL_RNG_GetRandomNumber(&hrng);
}
while (i < sz) {
/* If not aligned or there is odd/remainder */
if( (i + sizeof(word32)) > sz ||
((wolfssl_word)&output[i] % sizeof(word32)) != 0
) {
/* Single byte at a time */
word32 tmpRng = 0;
if (HAL_RNG_GenerateRandomNumber(&hrng, &tmpRng) != HAL_OK) {
return RAN_BLOCK_E;
}
output[i++] = (byte)tmpRng;
}
else {
/* Use native 32 instruction */
if (HAL_RNG_GenerateRandomNumber(&hrng, (word32*)&output[i]) != HAL_OK) {
return RAN_BLOCK_E;
}
i += sizeof(word32);
}
}
return 0;
return 0;
}
#elif defined(WOLFSSL_STM32F427_RNG)
#elif defined(WOLFSSL_STM32F427_RNG) || defined(WOLFSSL_STM32_RNG_NOLIB)
/* Generate a RNG seed using the hardware RNG on the STM32F427
* directly, following steps outlined in STM32F4 Reference