frost/secp256k1-zkp
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Fix miscellaneous style nits that irritate overactive static analysis.

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Also increase consistency with how overflow && zero is tested, and
 avoid some mixed declarations and code that GCC wasn't detecting.
This commit is contained in:
Gregory Maxwell
2015-09-24 08:42:37 +00:00
parent 9e9051687c
commit cfe0ed916a
13 changed files with 45 additions and 43 deletions
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12
src/ecmult_const_impl.h
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@@ -55,7 +55,7 @@
* Numbers reference steps of `Algorithm SPA-resistant Width-w NAF with Odd Scalar` on pp. 335
*/
static int secp256k1_wnaf_const(int *wnaf, secp256k1_scalar s, int w) {
int global_sign = 1;
int global_sign;
int skew = 0;
int word = 0;
/* 1 2 3 */
@@ -63,6 +63,10 @@ static int secp256k1_wnaf_const(int *wnaf, secp256k1_scalar s, int w) {
int u;
#ifdef USE_ENDOMORPHISM
int flip;
int bit;
secp256k1_scalar neg_s;
int not_neg_one;
/* If we are using the endomorphism, we cannot handle even numbers by negating
* them, since we are working with 128-bit numbers whose negations would be 256
* bits, eliminating the performance advantage. Instead we use a technique from
@@ -70,12 +74,10 @@ static int secp256k1_wnaf_const(int *wnaf, secp256k1_scalar s, int w) {
* or 2 (for odd) to the number we are encoding, then compensating after the
* multiplication. */
/* Negative 128-bit numbers will be negated, since otherwise they are 256-bit */
int flip = secp256k1_scalar_is_high(&s);
flip = secp256k1_scalar_is_high(&s);
/* We add 1 to even numbers, 2 to odd ones, noting that negation flips parity */
int bit = flip ^ (s.d[0] & 1);
bit = flip ^ (s.d[0] & 1);
/* We check for negative one, since adding 2 to it will cause an overflow */
secp256k1_scalar neg_s;
int not_neg_one;
secp256k1_scalar_negate(&neg_s, &s);
not_neg_one = !secp256k1_scalar_is_one(&neg_s);
secp256k1_scalar_cadd_bit(&s, bit, not_neg_one);