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- 'use strict';
- var utils = require('../utils');
- var BN = require('bn.js');
- var inherits = require('inherits');
- var Base = require('./base');
- var assert = utils.assert;
- function EdwardsCurve(conf) {
- // NOTE: Important as we are creating point in Base.call()
- this.twisted = (conf.a | 0) !== 1;
- this.mOneA = this.twisted && (conf.a | 0) === -1;
- this.extended = this.mOneA;
- Base.call(this, 'edwards', conf);
- this.a = new BN(conf.a, 16).umod(this.red.m);
- this.a = this.a.toRed(this.red);
- this.c = new BN(conf.c, 16).toRed(this.red);
- this.c2 = this.c.redSqr();
- this.d = new BN(conf.d, 16).toRed(this.red);
- this.dd = this.d.redAdd(this.d);
- assert(!this.twisted || this.c.fromRed().cmpn(1) === 0);
- this.oneC = (conf.c | 0) === 1;
- }
- inherits(EdwardsCurve, Base);
- module.exports = EdwardsCurve;
- EdwardsCurve.prototype._mulA = function _mulA(num) {
- if (this.mOneA)
- return num.redNeg();
- else
- return this.a.redMul(num);
- };
- EdwardsCurve.prototype._mulC = function _mulC(num) {
- if (this.oneC)
- return num;
- else
- return this.c.redMul(num);
- };
- // Just for compatibility with Short curve
- EdwardsCurve.prototype.jpoint = function jpoint(x, y, z, t) {
- return this.point(x, y, z, t);
- };
- EdwardsCurve.prototype.pointFromX = function pointFromX(x, odd) {
- x = new BN(x, 16);
- if (!x.red)
- x = x.toRed(this.red);
- var x2 = x.redSqr();
- var rhs = this.c2.redSub(this.a.redMul(x2));
- var lhs = this.one.redSub(this.c2.redMul(this.d).redMul(x2));
- var y2 = rhs.redMul(lhs.redInvm());
- var y = y2.redSqrt();
- if (y.redSqr().redSub(y2).cmp(this.zero) !== 0)
- throw new Error('invalid point');
- var isOdd = y.fromRed().isOdd();
- if (odd && !isOdd || !odd && isOdd)
- y = y.redNeg();
- return this.point(x, y);
- };
- EdwardsCurve.prototype.pointFromY = function pointFromY(y, odd) {
- y = new BN(y, 16);
- if (!y.red)
- y = y.toRed(this.red);
- // x^2 = (y^2 - c^2) / (c^2 d y^2 - a)
- var y2 = y.redSqr();
- var lhs = y2.redSub(this.c2);
- var rhs = y2.redMul(this.d).redMul(this.c2).redSub(this.a);
- var x2 = lhs.redMul(rhs.redInvm());
- if (x2.cmp(this.zero) === 0) {
- if (odd)
- throw new Error('invalid point');
- else
- return this.point(this.zero, y);
- }
- var x = x2.redSqrt();
- if (x.redSqr().redSub(x2).cmp(this.zero) !== 0)
- throw new Error('invalid point');
- if (x.fromRed().isOdd() !== odd)
- x = x.redNeg();
- return this.point(x, y);
- };
- EdwardsCurve.prototype.validate = function validate(point) {
- if (point.isInfinity())
- return true;
- // Curve: A * X^2 + Y^2 = C^2 * (1 + D * X^2 * Y^2)
- point.normalize();
- var x2 = point.x.redSqr();
- var y2 = point.y.redSqr();
- var lhs = x2.redMul(this.a).redAdd(y2);
- var rhs = this.c2.redMul(this.one.redAdd(this.d.redMul(x2).redMul(y2)));
- return lhs.cmp(rhs) === 0;
- };
- function Point(curve, x, y, z, t) {
- Base.BasePoint.call(this, curve, 'projective');
- if (x === null && y === null && z === null) {
- this.x = this.curve.zero;
- this.y = this.curve.one;
- this.z = this.curve.one;
- this.t = this.curve.zero;
- this.zOne = true;
- } else {
- this.x = new BN(x, 16);
- this.y = new BN(y, 16);
- this.z = z ? new BN(z, 16) : this.curve.one;
- this.t = t && new BN(t, 16);
- if (!this.x.red)
- this.x = this.x.toRed(this.curve.red);
- if (!this.y.red)
- this.y = this.y.toRed(this.curve.red);
- if (!this.z.red)
- this.z = this.z.toRed(this.curve.red);
- if (this.t && !this.t.red)
- this.t = this.t.toRed(this.curve.red);
- this.zOne = this.z === this.curve.one;
- // Use extended coordinates
- if (this.curve.extended && !this.t) {
- this.t = this.x.redMul(this.y);
- if (!this.zOne)
- this.t = this.t.redMul(this.z.redInvm());
- }
- }
- }
- inherits(Point, Base.BasePoint);
- EdwardsCurve.prototype.pointFromJSON = function pointFromJSON(obj) {
- return Point.fromJSON(this, obj);
- };
- EdwardsCurve.prototype.point = function point(x, y, z, t) {
- return new Point(this, x, y, z, t);
- };
- Point.fromJSON = function fromJSON(curve, obj) {
- return new Point(curve, obj[0], obj[1], obj[2]);
- };
- Point.prototype.inspect = function inspect() {
- if (this.isInfinity())
- return '<EC Point Infinity>';
- return '<EC Point x: ' + this.x.fromRed().toString(16, 2) +
- ' y: ' + this.y.fromRed().toString(16, 2) +
- ' z: ' + this.z.fromRed().toString(16, 2) + '>';
- };
- Point.prototype.isInfinity = function isInfinity() {
- // XXX This code assumes that zero is always zero in red
- return this.x.cmpn(0) === 0 &&
- (this.y.cmp(this.z) === 0 ||
- (this.zOne && this.y.cmp(this.curve.c) === 0));
- };
- Point.prototype._extDbl = function _extDbl() {
- // hyperelliptic.org/EFD/g1p/auto-twisted-extended-1.html
- // #doubling-dbl-2008-hwcd
- // 4M + 4S
- // A = X1^2
- var a = this.x.redSqr();
- // B = Y1^2
- var b = this.y.redSqr();
- // C = 2 * Z1^2
- var c = this.z.redSqr();
- c = c.redIAdd(c);
- // D = a * A
- var d = this.curve._mulA(a);
- // E = (X1 + Y1)^2 - A - B
- var e = this.x.redAdd(this.y).redSqr().redISub(a).redISub(b);
- // G = D + B
- var g = d.redAdd(b);
- // F = G - C
- var f = g.redSub(c);
- // H = D - B
- var h = d.redSub(b);
- // X3 = E * F
- var nx = e.redMul(f);
- // Y3 = G * H
- var ny = g.redMul(h);
- // T3 = E * H
- var nt = e.redMul(h);
- // Z3 = F * G
- var nz = f.redMul(g);
- return this.curve.point(nx, ny, nz, nt);
- };
- Point.prototype._projDbl = function _projDbl() {
- // hyperelliptic.org/EFD/g1p/auto-twisted-projective.html
- // #doubling-dbl-2008-bbjlp
- // #doubling-dbl-2007-bl
- // and others
- // Generally 3M + 4S or 2M + 4S
- // B = (X1 + Y1)^2
- var b = this.x.redAdd(this.y).redSqr();
- // C = X1^2
- var c = this.x.redSqr();
- // D = Y1^2
- var d = this.y.redSqr();
- var nx;
- var ny;
- var nz;
- var e;
- var h;
- var j;
- if (this.curve.twisted) {
- // E = a * C
- e = this.curve._mulA(c);
- // F = E + D
- var f = e.redAdd(d);
- if (this.zOne) {
- // X3 = (B - C - D) * (F - 2)
- nx = b.redSub(c).redSub(d).redMul(f.redSub(this.curve.two));
- // Y3 = F * (E - D)
- ny = f.redMul(e.redSub(d));
- // Z3 = F^2 - 2 * F
- nz = f.redSqr().redSub(f).redSub(f);
- } else {
- // H = Z1^2
- h = this.z.redSqr();
- // J = F - 2 * H
- j = f.redSub(h).redISub(h);
- // X3 = (B-C-D)*J
- nx = b.redSub(c).redISub(d).redMul(j);
- // Y3 = F * (E - D)
- ny = f.redMul(e.redSub(d));
- // Z3 = F * J
- nz = f.redMul(j);
- }
- } else {
- // E = C + D
- e = c.redAdd(d);
- // H = (c * Z1)^2
- h = this.curve._mulC(this.z).redSqr();
- // J = E - 2 * H
- j = e.redSub(h).redSub(h);
- // X3 = c * (B - E) * J
- nx = this.curve._mulC(b.redISub(e)).redMul(j);
- // Y3 = c * E * (C - D)
- ny = this.curve._mulC(e).redMul(c.redISub(d));
- // Z3 = E * J
- nz = e.redMul(j);
- }
- return this.curve.point(nx, ny, nz);
- };
- Point.prototype.dbl = function dbl() {
- if (this.isInfinity())
- return this;
- // Double in extended coordinates
- if (this.curve.extended)
- return this._extDbl();
- else
- return this._projDbl();
- };
- Point.prototype._extAdd = function _extAdd(p) {
- // hyperelliptic.org/EFD/g1p/auto-twisted-extended-1.html
- // #addition-add-2008-hwcd-3
- // 8M
- // A = (Y1 - X1) * (Y2 - X2)
- var a = this.y.redSub(this.x).redMul(p.y.redSub(p.x));
- // B = (Y1 + X1) * (Y2 + X2)
- var b = this.y.redAdd(this.x).redMul(p.y.redAdd(p.x));
- // C = T1 * k * T2
- var c = this.t.redMul(this.curve.dd).redMul(p.t);
- // D = Z1 * 2 * Z2
- var d = this.z.redMul(p.z.redAdd(p.z));
- // E = B - A
- var e = b.redSub(a);
- // F = D - C
- var f = d.redSub(c);
- // G = D + C
- var g = d.redAdd(c);
- // H = B + A
- var h = b.redAdd(a);
- // X3 = E * F
- var nx = e.redMul(f);
- // Y3 = G * H
- var ny = g.redMul(h);
- // T3 = E * H
- var nt = e.redMul(h);
- // Z3 = F * G
- var nz = f.redMul(g);
- return this.curve.point(nx, ny, nz, nt);
- };
- Point.prototype._projAdd = function _projAdd(p) {
- // hyperelliptic.org/EFD/g1p/auto-twisted-projective.html
- // #addition-add-2008-bbjlp
- // #addition-add-2007-bl
- // 10M + 1S
- // A = Z1 * Z2
- var a = this.z.redMul(p.z);
- // B = A^2
- var b = a.redSqr();
- // C = X1 * X2
- var c = this.x.redMul(p.x);
- // D = Y1 * Y2
- var d = this.y.redMul(p.y);
- // E = d * C * D
- var e = this.curve.d.redMul(c).redMul(d);
- // F = B - E
- var f = b.redSub(e);
- // G = B + E
- var g = b.redAdd(e);
- // X3 = A * F * ((X1 + Y1) * (X2 + Y2) - C - D)
- var tmp = this.x.redAdd(this.y).redMul(p.x.redAdd(p.y)).redISub(c).redISub(d);
- var nx = a.redMul(f).redMul(tmp);
- var ny;
- var nz;
- if (this.curve.twisted) {
- // Y3 = A * G * (D - a * C)
- ny = a.redMul(g).redMul(d.redSub(this.curve._mulA(c)));
- // Z3 = F * G
- nz = f.redMul(g);
- } else {
- // Y3 = A * G * (D - C)
- ny = a.redMul(g).redMul(d.redSub(c));
- // Z3 = c * F * G
- nz = this.curve._mulC(f).redMul(g);
- }
- return this.curve.point(nx, ny, nz);
- };
- Point.prototype.add = function add(p) {
- if (this.isInfinity())
- return p;
- if (p.isInfinity())
- return this;
- if (this.curve.extended)
- return this._extAdd(p);
- else
- return this._projAdd(p);
- };
- Point.prototype.mul = function mul(k) {
- if (this._hasDoubles(k))
- return this.curve._fixedNafMul(this, k);
- else
- return this.curve._wnafMul(this, k);
- };
- Point.prototype.mulAdd = function mulAdd(k1, p, k2) {
- return this.curve._wnafMulAdd(1, [ this, p ], [ k1, k2 ], 2, false);
- };
- Point.prototype.jmulAdd = function jmulAdd(k1, p, k2) {
- return this.curve._wnafMulAdd(1, [ this, p ], [ k1, k2 ], 2, true);
- };
- Point.prototype.normalize = function normalize() {
- if (this.zOne)
- return this;
- // Normalize coordinates
- var zi = this.z.redInvm();
- this.x = this.x.redMul(zi);
- this.y = this.y.redMul(zi);
- if (this.t)
- this.t = this.t.redMul(zi);
- this.z = this.curve.one;
- this.zOne = true;
- return this;
- };
- Point.prototype.neg = function neg() {
- return this.curve.point(this.x.redNeg(),
- this.y,
- this.z,
- this.t && this.t.redNeg());
- };
- Point.prototype.getX = function getX() {
- this.normalize();
- return this.x.fromRed();
- };
- Point.prototype.getY = function getY() {
- this.normalize();
- return this.y.fromRed();
- };
- Point.prototype.eq = function eq(other) {
- return this === other ||
- this.getX().cmp(other.getX()) === 0 &&
- this.getY().cmp(other.getY()) === 0;
- };
- Point.prototype.eqXToP = function eqXToP(x) {
- var rx = x.toRed(this.curve.red).redMul(this.z);
- if (this.x.cmp(rx) === 0)
- return true;
- var xc = x.clone();
- var t = this.curve.redN.redMul(this.z);
- for (;;) {
- xc.iadd(this.curve.n);
- if (xc.cmp(this.curve.p) >= 0)
- return false;
- rx.redIAdd(t);
- if (this.x.cmp(rx) === 0)
- return true;
- }
- };
- // Compatibility with BaseCurve
- Point.prototype.toP = Point.prototype.normalize;
- Point.prototype.mixedAdd = Point.prototype.add;
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