98 lines
2.4 KiB
JavaScript
98 lines
2.4 KiB
JavaScript
var bn = require("./bn.js");
|
|
|
|
var brorand = require("./brorand.js");
|
|
|
|
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;
|
|
}; |