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secp256k1
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A few improvements to the sqrt tests

This commit is contained in:
Peter Dettman 2014-06-03 17:50:27 +07:00
parent 5355746867
commit 6d6102fee4
1 changed files with 38 additions and 10 deletions
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48
src/tests.c
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@ -217,18 +217,26 @@ void random_fe(secp256k1_fe_t *x) {
secp256k1_fe_set_b32(x, bin); secp256k1_fe_set_b32(x, bin);
} }
void random_fe_non_square(secp256k1_fe_t *ns) { void random_fe_non_zero(secp256k1_fe_t *nz) {
secp256k1_fe_t r; int tries = 10;
int tries = 100;
while (--tries >= 0) { while (--tries >= 0) {
random_fe(ns); random_fe(nz);
if (!secp256k1_fe_sqrt(&r, ns)) secp256k1_fe_normalize(nz);
if (!secp256k1_fe_is_zero(nz))
break; break;
} }
// 2^-100 probability of spurious failure here // Infinitesimal probability of spurious failure here
assert(tries >= 0); 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) { void test_sqrt(const secp256k1_fe_t *a, const secp256k1_fe_t *k) {
secp256k1_fe_t r1, r2; secp256k1_fe_t r1, r2;
int v = secp256k1_fe_sqrt(&r1, a); int v = secp256k1_fe_sqrt(&r1, a);
@ -245,14 +253,34 @@ void test_sqrt(const secp256k1_fe_t *a, const secp256k1_fe_t *k) {
void run_sqrt() { void run_sqrt() {
secp256k1_fe_t ns, x, s, t; secp256k1_fe_t ns, x, s, t;
random_fe_non_square(&ns);
for (int i=0; i<10*count; i++) { // Check sqrt(0) is 0
random_fe(&x); 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); secp256k1_fe_sqr(&s, &x);
test_sqrt(&s, &x); test_sqrt(&s, &x);
secp256k1_fe_mul(&t, &s, &ns); secp256k1_fe_negate(&t, &s, 1);
test_sqrt(&t, NULL); 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 *****/ /***** ECMULT TESTS *****/