fix Point.prototype.toJSON for short curves

lib/elliptic/curve/short.js

@@ -311,9 +311,9 @@ Point.prototype._getBeta = function _getBeta() {
 
 Point.prototype.toJSON = function toJSON() {
   if (!this.precomputed)
-    return [ this.x, this.y ];
+    return [ this.x.fromRed(), this.y.fromRed() ];
 
-  return [ this.x, this.y, this.precomputed && {
+  return [ this.x.fromRed(), this.y.fromRed(), this.precomputed && {
     doubles: this.precomputed.doubles && {
       step: this.precomputed.doubles.step,
       points: this.precomputed.doubles.points.slice(1)

test/index.js

@@ -4,4 +4,5 @@ describe('Test specs', function () {
   require('./ecdh-test.js');
   require('./ecdsa-test.js');
   require('./ed25519-test.js');
+  require('./toJSON-test.js');
 });

test/toJSON-test.js

@@ -0,0 +1,28 @@
+'use strict';
+
+var fs = require('fs');
+var path = require('path');
+var assert = require('assert');
+var elliptic = require('../lib/elliptic');
+var curves = elliptic.curves;
+var compare = assert.deepStrictEqual || assert.deepEqual;
+
+function exportPoint (p) {
+  return JSON.parse(JSON.stringify(p.toJSON()));
+}
+
+describe('toJSON <-> pointFromJSON symmetry', function() {
+  it('toJSON is the inverse of pointFromJSON', function () {
+    for (var key in curves) {
+      if (key === 'PresetCurve') continue;
+
+      var curve = curves[key];
+      if (!curve.g.toJSON) continue;
+
+      var exported = exportPoint(curve.g);
+      var reimported = curve.curve.pointFromJSON(exported);
+      var reexported = exportPoint(reimported);
+      compare(exported, reexported, 'toJSON is the inverse of pointFromJSON');
+    }
+  });
+});