frost/secp256k1-zkp
3
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Eliminate all side-effects from VERIFY_CHECK() usage.

Browse Source 
The side-effects make review somewhat harder because 99.9% of the
 time the macro usage has no sideeffects, so they're easily ignored.

The main motivation for avoiding the side effects is so that the
 macro can be completely stubbed out for branch coverage analysis
 otherwise all the unreachable verify code gets counted against
 coverage.
This commit is contained in:
Gregory Maxwell
2015-10-19 23:55:10 +00:00
parent b30fc85c9e
commit e3cd679634
4 changed files with 17 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
src/field_impl.h
View File

@@ -224,6 +224,7 @@ static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a) {
0xFF,0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F
};
unsigned char b[32];
int res;
secp256k1_fe c = *a;
secp256k1_fe_normalize_var(&c);
secp256k1_fe_get_b32(b, &c);
@@ -231,7 +232,9 @@ static void secp256k1_fe_inv_var(secp256k1_fe *r, const secp256k1_fe *a) {
secp256k1_num_set_bin(&m, prime, 32);
secp256k1_num_mod_inverse(&n, &n, &m);
secp256k1_num_get_bin(b, 32, &n);
VERIFY_CHECK(secp256k1_fe_set_b32(r, b));
res = secp256k1_fe_set_b32(r, b);
(void)res;
VERIFY_CHECK(res);
/* Verify the result is the (unique) valid inverse using non-GMP code. */
secp256k1_fe_mul(&c, &c, r);
secp256k1_fe_add(&c, &negone);