README.md

ESPRandom

Generate random numbers and UUIDs on the ESP8266 and ESP32 using the hardware RNG. Due to changes in requirements, I have moved to a different approach which has been implemented in the following library: ESP UUID. It supports ArduinoJson and std::map. Pull requests will be accepted here, but no active contribution from my side will be made.

Examples

Get a Guaranteed Random Number

#include "Arduino.h"
#include "ESPRandom.h"

void setup() {
  Serial.begin(115200);
}

void loop() {
  Serial.println(ESPRandom::get());
  delay(1000);
}

Get a Very Unique UUID

#include "Arduino.h"
#include "ESPRandom.h"

void setup() {
  Serial.begin(115200);
}

void loop() {
  uint8_t uuid[16];
  ESPRandom::uuid(uuid);
  Serial.println(ESPRandom::uuidToString(uuid));
  delay(1000);
}

Sunny Conditions for Random Numbers

For random numbers to be generated, the radio (WiFi or Bluetooth) have to be active. Therefore, when getting a random number (or UUID) it will check if WiFi is active and activate it (in station mode) if this is not the case.

Another reason for creating this library is that the alternatives are covered in copy-left licences which significantly restrict their use.

Randomness Test

Test Name	Rewinds	tsamples	psamples	p-value	Assessment
diehard_birthdays	1	100	100	0.08369138	PASSED
diehard_operm5	8	1000000	100	0.14173840	PASSED
diehard_rank_32x32	18	40000	100	0.00000000	FAILED
diehard_rank_6x8	22	100000	100	0.95923936	PASSED
diehard_bitstream	24	2097152	100	0.19399156	PASSED
diehard_opso	40	2097152	100	0.00055960	WEAK
diehard_oqso	50	2097152	100	0.55745812	PASSED
diehard_dna	55	2097152	100	0.08215937	PASSED

Attribution

Derived the UUID v1 generation algorithm from the stduuid library.