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Micro-optimize DSA signing

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This commit is contained in:
Daniel Huigens 2018-05-01 17:34:55 +02:00
parent 0ae427060f
commit 6e27e3145c
1 changed files with 3 additions and 2 deletions
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5
src/crypto/public_key/dsa.js
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@ -68,7 +68,8 @@ export default {
// directly in the DSA signature algorithm.
const h = new BN(
util.getLeftNBits(
hash.digest(hash_algo, m), q.bitLength()));
hash.digest(hash_algo, m), q.bitLength()))
.toRed(redq);
// FIPS-186-4, section 4.6:
// The values of r and s shall be checked to determine if r = 0 or s = 0.
// If either r = 0 or s = 0, a new value of k shall be generated, and the
@ -82,7 +83,7 @@ export default {
if (zero.cmp(r) === 0) {
continue;
}
t = h.add(x.mul(r)).toRed(redq); // H(m) + x*r mod q
t = h.redAdd(xred.redMul(r)); // H(m) + x*r mod q
s = k.toRed(redq).redInvm().redMul(t); // k**-1 * (H(m) + x*r) mod q
if (zero.cmp(s) === 0) {
continue;