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A few improvements to the sqrt tests

master
Peter Dettman 8 years ago
parent
commit
6d6102fee4
  1. 48
      src/tests.c

48
src/tests.c

@ -217,18 +217,26 @@ void random_fe(secp256k1_fe_t *x) { @@ -217,18 +217,26 @@ void random_fe(secp256k1_fe_t *x) {
secp256k1_fe_set_b32(x, bin);
}
void random_fe_non_square(secp256k1_fe_t *ns) {
secp256k1_fe_t r;
int tries = 100;
void random_fe_non_zero(secp256k1_fe_t *nz) {
int tries = 10;
while (--tries >= 0) {
random_fe(ns);
if (!secp256k1_fe_sqrt(&r, ns))
random_fe(nz);
secp256k1_fe_normalize(nz);
if (!secp256k1_fe_is_zero(nz))
break;
}
// 2^-100 probability of spurious failure here
// Infinitesimal probability of spurious failure here
assert(tries >= 0);
}
void random_fe_non_square(secp256k1_fe_t *ns) {
random_fe_non_zero(ns);
secp256k1_fe_t r;
if (secp256k1_fe_sqrt(&r, ns)) {
secp256k1_fe_negate(ns, ns, 1);
}
}
void test_sqrt(const secp256k1_fe_t *a, const secp256k1_fe_t *k) {
secp256k1_fe_t r1, r2;
int v = secp256k1_fe_sqrt(&r1, a);
@ -245,14 +253,34 @@ void test_sqrt(const secp256k1_fe_t *a, const secp256k1_fe_t *k) { @@ -245,14 +253,34 @@ void test_sqrt(const secp256k1_fe_t *a, const secp256k1_fe_t *k) {
void run_sqrt() {
secp256k1_fe_t ns, x, s, t;
random_fe_non_square(&ns);
for (int i=0; i<10*count; i++) {
random_fe(&x);
// Check sqrt(0) is 0
secp256k1_fe_set_int(&x, 0);
secp256k1_fe_sqr(&s, &x);
test_sqrt(&s, &x);
// Check sqrt of small squares (and their negatives)
for (int i=1; i<=100; i++) {
secp256k1_fe_set_int(&x, i);
secp256k1_fe_sqr(&s, &x);
test_sqrt(&s, &x);
secp256k1_fe_mul(&t, &s, &ns);
secp256k1_fe_negate(&t, &s, 1);
test_sqrt(&t, NULL);
}
// Consistency checks for large random values
for (int i=0; i<10; i++) {
random_fe_non_square(&ns);
for (int j=0; j<count; j++) {
random_fe(&x);
secp256k1_fe_sqr(&s, &x);
test_sqrt(&s, &x);
secp256k1_fe_negate(&t, &s, 1);
test_sqrt(&t, NULL);
secp256k1_fe_mul(&t, &s, &ns);
test_sqrt(&t, NULL);
}
}
}
/***** ECMULT TESTS *****/

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