0.2.0 - Mid migration

web/node_modules/miller-rabin/lib/mr.js

@@ -0,0 +1,115 @@
+var bn = require('bn.js');
+var brorand = require('brorand');
+
+function MillerRabin(rand) {
+  this.rand = rand || new brorand.Rand();
+}
+module.exports = MillerRabin;
+
+MillerRabin.create = function create(rand) {
+  return new MillerRabin(rand);
+};
+
+MillerRabin.prototype._randbelow = function _randbelow(n) {
+  var len = n.bitLength();
+  var min_bytes = Math.ceil(len / 8);
+
+  // Generage random bytes until a number less than n is found.
+  // This ensures that 0..n-1 have an equal probability of being selected.
+  do
+    var a = new bn(this.rand.generate(min_bytes));
+  while (a.cmp(n) >= 0);
+
+  return a;
+};
+
+MillerRabin.prototype._randrange = function _randrange(start, stop) {
+  // Generate a random number greater than or equal to start and less than stop.
+  var size = stop.sub(start);
+  return start.add(this._randbelow(size));
+};
+
+MillerRabin.prototype.test = function test(n, k, cb) {
+  var len = n.bitLength();
+  var red = bn.mont(n);
+  var rone = new bn(1).toRed(red);
+
+  if (!k)
+    k = Math.max(1, (len / 48) | 0);
+
+  // Find d and s, (n - 1) = (2 ^ s) * d;
+  var n1 = n.subn(1);
+  for (var s = 0; !n1.testn(s); s++) {}
+  var d = n.shrn(s);
+
+  var rn1 = n1.toRed(red);
+
+  var prime = true;
+  for (; k > 0; k--) {
+    var a = this._randrange(new bn(2), n1);
+    if (cb)
+      cb(a);
+
+    var x = a.toRed(red).redPow(d);
+    if (x.cmp(rone) === 0 || x.cmp(rn1) === 0)
+      continue;
+
+    for (var i = 1; i < s; i++) {
+      x = x.redSqr();
+
+      if (x.cmp(rone) === 0)
+        return false;
+      if (x.cmp(rn1) === 0)
+        break;
+    }
+
+    if (i === s)
+      return false;
+  }
+
+  return prime;
+};
+
+MillerRabin.prototype.getDivisor = function getDivisor(n, k) {
+  var len = n.bitLength();
+  var red = bn.mont(n);
+  var rone = new bn(1).toRed(red);
+
+  if (!k)
+    k = Math.max(1, (len / 48) | 0);
+
+  // Find d and s, (n - 1) = (2 ^ s) * d;
+  var n1 = n.subn(1);
+  for (var s = 0; !n1.testn(s); s++) {}
+  var d = n.shrn(s);
+
+  var rn1 = n1.toRed(red);
+
+  for (; k > 0; k--) {
+    var a = this._randrange(new bn(2), n1);
+
+    var g = n.gcd(a);
+    if (g.cmpn(1) !== 0)
+      return g;
+
+    var x = a.toRed(red).redPow(d);
+    if (x.cmp(rone) === 0 || x.cmp(rn1) === 0)
+      continue;
+
+    for (var i = 1; i < s; i++) {
+      x = x.redSqr();
+
+      if (x.cmp(rone) === 0)
+        return x.fromRed().subn(1).gcd(n);
+      if (x.cmp(rn1) === 0)
+        break;
+    }
+
+    if (i === s) {
+      x = x.redSqr();
+      return x.fromRed().subn(1).gcd(n);
+    }
+  }
+
+  return false;
+};