--- /dev/null
+"use strict";
+/**
+ * @fileOverview
+ * EC Diffie-Hellman operations on Curve25519.
+ */
+
+/*
+ * Copyright (c) 2014 Mega Limited
+ * under the MIT License.
+ *
+ * Authors: Guy K. Kloss
+ *
+ * You should have received a copy of the license along with this program.
+ */
+
+var core = require('./core');
+var utils = require('./utils');
+var curve255 = require('./curve255');
+
+
+ /**
+ * @exports jodid25519/dh
+ * EC Diffie-Hellman operations on Curve25519.
+ *
+ * @description
+ * EC Diffie-Hellman operations on Curve25519.
+ */
+ var ns = {};
+
+
+ function _toString(vector) {
+ var u = new Uint16Array(vector);
+ return (new Buffer(new Uint8Array(u.buffer)));
+ }
+
+ function _fromString(vector) {
+ if (Buffer.isBuffer(vector)) {
+ var u = new Uint8Array(vector);
+ return (new Uint16Array(u.buffer));
+ }
+
+ var result = new Array(16);
+ for (var i = 0, l = 0; i < vector.length; i += 2) {
+ result[l] = (vector.charCodeAt(i + 1) << 8) | vector.charCodeAt(i);
+ l++;
+ }
+ return result;
+ }
+
+
+ /**
+ * Computes a key through scalar multiplication of a point on the curve 25519.
+ *
+ * This function is used for the DH key-exchange protocol. It computes a
+ * key based on a secret key with a public component (opponent's public key
+ * or curve base point if not given) by using scalar multiplication.
+ *
+ * Before multiplication, some bit operations are applied to the
+ * private key to ensure it is a valid Curve25519 secret key.
+ * It is the user's responsibility to make sure that the private
+ * key is a uniformly random, secret value.
+ *
+ * @function
+ * @param privateComponent {string}
+ * Private point as byte string on the curve.
+ * @param publicComponent {string}
+ * Public point as byte string on the curve. If not given, the curve's
+ * base point is used.
+ * @returns {string}
+ * Key point as byte string resulting from scalar product.
+ */
+ ns.computeKey = function(privateComponent, publicComponent) {
+ if (publicComponent) {
+ return _toString(curve255.curve25519(_fromString(privateComponent),
+ _fromString(publicComponent)));
+ } else {
+ return _toString(curve255.curve25519(_fromString(privateComponent)));
+ }
+ };
+
+ /**
+ * Computes the public key to a private key on the curve 25519.
+ *
+ * Before multiplication, some bit operations are applied to the
+ * private key to ensure it is a valid Curve25519 secret key.
+ * It is the user's responsibility to make sure that the private
+ * key is a uniformly random, secret value.
+ *
+ * @function
+ * @param privateKey {string}
+ * Private point as byte string on the curve.
+ * @returns {string}
+ * Public key point as byte string resulting from scalar product.
+ */
+ ns.publicKey = function(privateKey) {
+ return _toString(curve255.curve25519(_fromString(privateKey)));
+ };
+
+
+ /**
+ * Generates a new random private key of 32 bytes length (256 bit).
+ *
+ * @function
+ * @returns {string}
+ * Byte string containing a new random private key seed.
+ */
+ ns.generateKey = function() {
+ return core.generateKey(true);
+ };
+
+module.exports = ns;