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This commit is contained in:
Mickey Malone
2021-02-13 09:58:22 -06:00
parent 53a9d6bdf3
commit 15316f2a51
1 changed files with 2 additions and 21 deletions
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23
firmware/pico_rng.c
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@@ -539,7 +539,8 @@ void ep0_out_handler(uint8_t *buf, uint16_t len) {
} }
/** /**
* @brief Get random data using the onboard pico ADC. * @brief Get random data using the onboard pico ADC that essentially measure
* environmental noise because it is assumed that it is not connected to anything.
* *
* @param buf the buffer to store the random data in * @param buf the buffer to store the random data in
* @param len the length of the random data in bytes * @param len the length of the random data in bytes
@@ -564,26 +565,6 @@ void get_random_data(char *buf, uint16_t len) {
memcpy(&buf[i-1], (void*)&adc_result, 2); memcpy(&buf[i-1], (void*)&adc_result, 2);
} }
// The pico has a clock, use it as the seed because time always changes
// https://raspberrypi.github.io/pico-sdk-doxygen/group__hardware__clocks.html
/**
* In an attempt to make the rng even more random this will slow down the amount of data the
* pico can generate. It appears to be more random, but not good enough for FIPS 140-2.
**/
/**
//Use the ADC as a seed to the arm gnu stdlib random number generator
srand((int)(adc_read() | (adc_read() << 16)));
memset(buf, 0, len);
int rand_result;
for(i = 0; i <= len-4; i=i+4)
{
rand_result = rand();
memcpy(&buf[i], (void*)&rand_result, 4);
}
**/
gpio_put(25, 0); gpio_put(25, 0);
} }