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ecdsa: ecurve 0.10.0

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This commit is contained in:
Daniel Cousens 2014-06-21 22:33:26 +10:00
parent b4e76ee199
commit 08876fc065
2 changed files with 3 additions and 20 deletions
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2
package.json
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@ -71,7 +71,7 @@
"dependencies": {
"bigi": "1.1.0",
"crypto-js": "3.1.2-3",
"ecurve": "0.9.0",
"ecurve": "0.10.0",
"secure-random": "0.2.1"
}
}

21
src/ecdsa.js
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@ -116,8 +116,7 @@ function recoverPubKey(curve, e, signature, i) {
var s = signature.s
// A set LSB signifies that the y-coordinate is odd
// By reduction, the y-coordinate is even if it is clear
var isYEven = !(i & 1)
var isYOdd = i & 1
// The more significant bit specifies whether we should use the
// first or second candidate key.
@ -125,28 +124,12 @@ function recoverPubKey(curve, e, signature, i) {
var n = curve.n
var G = curve.G
var p = curve.p
var a = curve.a
var b = curve.b
// We precalculate (p + 1) / 4 where p is the field order
if (!curve.P_OVER_FOUR) {
curve.P_OVER_FOUR = p.add(BigInteger.ONE).shiftRight(2)
}
// 1.1 Let x = r + jn
var x = isSecondKey ? r.add(n) : r
// 1.2, 1.3 Convert x to a point R using routine specified in Section 2.3.4
var alpha = x.pow(3).add(a.multiply(x)).add(b).mod(p)
var beta = alpha.modPow(curve.P_OVER_FOUR, p)
// If beta is even, but y isn't, or vice versa, then convert it,
// otherwise we're done and y == beta.
var y = (beta.isEven() ^ isYEven) ? p.subtract(beta) : beta
var R = curve.pointFromX(isYOdd, x)
// 1.4 Check that nR is at infinity
var R = Point.fromAffine(curve, x, y)
var nR = R.multiply(n)
assert(curve.isInfinity(nR), 'nR is not a valid curve point')