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#include <uECC.h>
extern "C" {
static int RNG(uint8_t *dest, unsigned size) {
// Use the least-significant bits from the ADC for an unconnected pin (or connected to a source of
// random noise). This can take a long time to generate random data if the result of analogRead(0)
// doesn't change very frequently.
while (size) {
uint8_t val = 0;
for (unsigned i = 0; i < 8; ++i) {
int init = analogRead(0);
int count = 0;
while (analogRead(0) == init) {
++count;
}
if (count == 0) {
val = (val << 1) | (init & 0x01);
} else {
val = (val << 1) | (count & 0x01);
}
}
*dest = val;
++dest;
--size;
}
// NOTE: it would be a good idea to hash the resulting random data using SHA-256 or similar.
return 1;
}
} // extern "C"
void setup() {
Serial.begin(115200);
Serial.print("Testing ecc\n");
uECC_set_rng(&RNG);
}
void loop() {
const struct uECC_Curve_t * curve = uECC_secp160r1();
uint8_t private1[21];
uint8_t private2[21];
uint8_t public1[40];
uint8_t public2[40];
uint8_t secret1[20];
uint8_t secret2[20];
unsigned long a = millis();
uECC_make_key(public1, private1, curve);
unsigned long b = millis();
Serial.print("Made key 1 in "); Serial.println(b-a);
a = millis();
uECC_make_key(public2, private2, curve);
b = millis();
Serial.print("Made key 2 in "); Serial.println(b-a);
a = millis();
int r = uECC_shared_secret(public2, private1, secret1, curve);
b = millis();
Serial.print("Shared secret 1 in "); Serial.println(b-a);
if (!r) {
Serial.print("shared_secret() failed (1)\n");
return;
}
a = millis();
r = uECC_shared_secret(public1, private2, secret2, curve);
b = millis();
Serial.print("Shared secret 2 in "); Serial.println(b-a);
if (!r) {
Serial.print("shared_secret() failed (2)\n");
return;
}
if (memcmp(secret1, secret2, 20) != 0) {
Serial.print("Shared secrets are not identical!\n");
} else {
Serial.print("Shared secrets are identical\n");
}
}
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