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Merge pull request #727 from thoatbk/master 

enforce low S values on key signing
This commit is contained in:
Manuel Aráoz 2014-12-12 13:05:20 -03:00
parent 100de8a9ba 28bb0f4cfc
commit 0d238f1165
1 changed files with 6 additions and 0 deletions
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6
lib/browser/Key.js
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@ -160,6 +160,12 @@ Key.sign = function(hash, priv, k) {
var Q = Point.multiply(G, k);
var r = Q.x.mod(n);
var s = k.invm(n).mul(e.add(d.mul(r))).mod(n);
//enforce low s
//see BIP 62, "low S values in signatures"
var n_half = bignum.fromBuffer(new Buffer("7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0", 'hex'), {size: 32});
if (s.cmp(n_half) > 0) {
s = new bignum(n).sub(s);
}
} while (r.cmp(new bignum(0)) <= 0 || s.cmp(new bignum(0)) <= 0);
return {r: r, s: s};