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tests: Fix test whose result is implementation-defined 

A compiler may add struct padding and fe_cmov is not guaranteed to
preserve it.

On the way, we improve the identity check such that it covers the
VERIFY struct members.
This commit is contained in:
Tim Ruffing 2021-12-23 19:28:08 +01:00
parent 09971a3ffd
commit 3d7cbafb5f
1 changed files with 11 additions and 8 deletions
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19
src/tests.c
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@ -2451,13 +2451,16 @@ void run_field_convert(void) {
CHECK(secp256k1_memcmp_var(&fes2, &fes, sizeof(fes)) == 0);
}
int fe_secp256k1_memcmp_var(const secp256k1_fe *a, const secp256k1_fe *b) {
secp256k1_fe t = *b;
/* Returns true if two field elements have the same representation. */
int fe_identical(const secp256k1_fe *a, const secp256k1_fe *b) {
int ret = 1;
#ifdef VERIFY
t.magnitude = a->magnitude;
t.normalized = a->normalized;
ret &= (a->magnitude == b->magnitude);
ret &= (a->normalized == b->normalized);
#endif
return secp256k1_memcmp_var(a, &t, sizeof(secp256k1_fe));
/* Compare the struct member that holds the limbs. */
ret &= (secp256k1_memcmp_var(a->n, b->n, sizeof(a->n)) == 0);
return ret;
}
void run_field_misc(void) {
@ -2483,13 +2486,13 @@ void run_field_misc(void) {
CHECK(x.normalized && x.magnitude == 1);
#endif
secp256k1_fe_cmov(&x, &x, 1);
CHECK(fe_secp256k1_memcmp_var(&x, &z) != 0);
CHECK(fe_secp256k1_memcmp_var(&x, &q) == 0);
CHECK(!fe_identical(&x, &z));
CHECK(fe_identical(&x, &q));
secp256k1_fe_cmov(&q, &z, 1);
#ifdef VERIFY
CHECK(!q.normalized && q.magnitude == z.magnitude);
#endif
CHECK(fe_secp256k1_memcmp_var(&q, &z) == 0);
CHECK(fe_identical(&q, &z));
secp256k1_fe_normalize_var(&x);
secp256k1_fe_normalize_var(&z);
CHECK(!secp256k1_fe_equal_var(&x, &z));