diff --git a/js/models/core/PrivateKey.js b/js/models/core/PrivateKey.js
index 7c220dadd..8df3325c7 100644
--- a/js/models/core/PrivateKey.js
+++ b/js/models/core/PrivateKey.js
@@ -1,23 +1,45 @@
 'use strict';
 
+// 62.9% typed (by google's closure-compiler account)
 
 var bitcore = require('bitcore');
 var HK = bitcore.HierarchicalKey;
 var WalletKey = bitcore.WalletKey;
 var networks = bitcore.networks;
 var util = bitcore.util;
+var _ = require('underscore');
+var preconditions = require('preconditions').instance();
 var HDPath = require('./HDPath');
 
+/**
+ * @desc
+ * Wrapper for bitcore.HierarchicalKey to be used inside of Copay.
+ *
+ * @param {Object} opts
+ * @param {string} opts.networkName if set to 'testnet', use the test3 bitcoin
+ *                                  network constants (livenet otherwise)
+ * @param {string} opts.extendedPrivateKeyString if set, use this private key
+ *                                               string, othewise create a new
+ *                                               private key
+ */
 function PrivateKey(opts) {
   opts = opts || {};
-  this.network = opts.networkName === 'testnet' ?
-    networks.testnet : networks.livenet;
+  this.network = opts.networkName === 'testnet' ?  networks.testnet : networks.livenet;
   var init = opts.extendedPrivateKeyString || this.network.name;
   this.bip = new HK(init);
   this.privateKeyCache = {};
   this.publicHex = this.deriveBIP45Branch().eckey.public.toString('hex');
 };
 
+/**
+ * @desc Retrieve this derivated private key's public key in hexa format
+ *
+ * The value returned is calculated using the path from PrivateKey's
+ * <tt>HDParams.IdFullBranch</tt>. This key is used to identify the copayer
+ * (signing messages mostly).
+ *
+ * @returns {string} the public key in a hexadecimal string
+ */
 PrivateKey.prototype.getId = function() {
   if (!this.id) {
     this.cacheId();
@@ -25,6 +47,15 @@ PrivateKey.prototype.getId = function() {
   return this.id;
 };
 
+/**
+ * @desc Retrieve this private key's private key in hex format
+ *
+ * The value returned is calculated using the path from PrivateKey's
+ * <tt>HDParams.IdFullBranch</tt>. This key is used to identify the copayer
+ * (signing messages mostly).
+ *
+ * @returns {string} the private key in a hexadecimal string
+ */
 PrivateKey.prototype.getIdPriv = function() {
   if (!this.idpriv) {
     this.cacheId();
@@ -32,6 +63,15 @@ PrivateKey.prototype.getIdPriv = function() {
   return this.idpriv;
 };
 
+/**
+ * @desc Retrieve this private key's private key
+ *
+ * The value returned is calculated using the path from PrivateKey's
+ * <tt>HDParams.IdFullBranch</tt>. This key is used to identify the copayer
+ * (signing messages mostly).
+ *
+ * @returns {bitcore.PrivateKey} the private key
+ */
 PrivateKey.prototype.getIdKey = function() {
   if (!this.idkey) {
     this.cacheId();
@@ -39,6 +79,11 @@ PrivateKey.prototype.getIdKey = function() {
   return this.idkey;
 };
 
+/**
+ * @desc Caches the result of deriving IdFullBranch
+ *
+ * @private
+ */
 PrivateKey.prototype.cacheId = function() {
   var path = HDPath.IdFullBranch;
   var idhk = this.bip.derive(path);
@@ -47,54 +92,116 @@ PrivateKey.prototype.cacheId = function() {
   this.idpriv = idhk.eckey.private.toString('hex');
 };
 
+/**
+ * @desc Derive the master branch for Copay.
+ */
 PrivateKey.prototype.deriveBIP45Branch = function() {
   if (!this.bip45Branch) {
     this.bip45Branch = this.bip.derive(HDPath.BIP45_PUBLIC_PREFIX);
   }
   return this.bip45Branch;
-}
-
-
-PrivateKey.trim = function(data) {
- var opts = {};
-  ['networkName', 'extendedPrivateKeyString'].forEach(function(k){
-   opts[k] = data[k];
-  });
-
-  return opts;
 };
 
+/**
+ * @desc Returns an object with information needed to rebuild a PrivateKey
+ * (as most of its properties are derived from the extended private key). 
+ *
+ * @TODO: Figure out if this is the correct pattern
+ * This is a static method and is probably used for serialization.
+ *
+ * @static
+ * @param {Object} data
+ * @param {*} data.networkName - a name for a bitcoin network
+ * @param {*} data.extendedPrivateKeyString - a bip32 extended private key
+ * @returns {Object} an object with two properties: networkName and
+ *                   extendedPrivateKeyString, taken from the <tt>data</tt>
+ *                   parameter.
+ */
+PrivateKey.trim = function(data) {
+  var opts = {};
+  ['networkName', 'extendedPrivateKeyString'].forEach(function(k){
+    opts[k] = data[k];
+  });
+  return opts
+};
+
+/**
+ * @desc Generate a private Key from a serialized object
+ *
+ * @TODO: This method uses PrivateKey.trim but it's actually not needed...
+ *
+ * @param {Object} data
+ * @param {*} data.networkName - a name for a bitcoin network
+ * @param {*} data.extendedPrivateKeyString - a bip32 extended private key
+ * @returns {PrivateKey}
+ */
 PrivateKey.fromObj = function(obj) {
   return new PrivateKey(PrivateKey.trim(obj));
 };
 
+/**
+ * @desc Serialize a private key, keeping only the data necessary to rebuild it
+ *
+ * @returns {Object}
+ */
 PrivateKey.prototype.toObj = function() {
   return {
     extendedPrivateKeyString: this.getExtendedPrivateKeyString(),
-    networkName: this.network.name,
+    networkName: this.network.name
   };
 };
 
+/**
+ * @desc Retrieve a BIP32 extended public key as generated by bitcore
+ *
+ * @returns {string}
+ */
 PrivateKey.prototype.getExtendedPublicKeyString = function() {
   return this.bip.extendedPublicKeyString();
 };
 
+/**
+ * @desc Retrieve a BIP32 extended private key as generated by bitcore
+ *
+ * @returns {string}
+ */
 PrivateKey.prototype.getExtendedPrivateKeyString = function() {
   return this.bip.extendedPrivateKeyString();
 };
 
+/**
+ * @desc
+ * Retrieve a HierarchicalKey derived from the given path as generated by
+ * bitcore
+ * @param {string} path - a string for derivation (something like "m/234'/1/2")
+ * @returns {bitcore.HierarchicalKey}
+ */
 PrivateKey.prototype._getHK = function(path) {
-  if (typeof path === 'undefined') {
+  if (_.isUndefined(path)) {
     return this.bip;
   }
   var ret = this.bip.derive(path);
   return ret;
 };
 
+/**
+ * @desc
+ * Retrieve an array of WalletKey derived from given paths. {@see PrivateKey#getForPath}
+ *
+ * @param {string[]} paths - the paths to derive
+ * @returns {bitcore.WalletKey[]} - the derived keys
+ */
 PrivateKey.prototype.getForPaths = function(paths) {
   return paths.map(this.getForPath.bind(this));
 };
 
+/**
+ * @desc
+ * Retrieve a WalletKey derived from a path.
+ *
+ * @param {string} paths - the path to derive
+ * @returns {bitcore.WalletKey} - the derived key
+ */
 PrivateKey.prototype.getForPath = function(path) {
   var pk = this.privateKeyCache[path];
   if (!pk) {
@@ -110,14 +217,38 @@ PrivateKey.prototype.getForPath = function(path) {
   return wk;
 };
 
+/**
+ * @desc
+ * Retrieve a Branch for Copay using the given path
+ *
+ * @TODO: Investigate when is this called and if this is really needed
+ *
+ * @param {number} index - the index of the key to generate
+ * @param {boolean} isChange - whether this is a change adderess or a receive
+ * @param {number} cosigner - the cosigner index
+ * @return {bitcore.HierarchicalKey}
+ */
 PrivateKey.prototype.get = function(index, isChange, cosigner) {
+
+  // TODO: Add parameter validation?
+
   var path = HDPath.FullBranch(index, isChange, cosigner);
   return this.getForPath(path);
 };
 
+/**
+ * @desc
+ * Retrieve multiple branches for Copay up to the received indexes
+ *
+ * @TODO: Investigate when is this called and if this is really needed
+ *
+ * @param {number} receiveIndex - the number of receive addresses to generate
+ * @param {number} changeIndex - the number of change addresses to generate
+ * @param {number} cosigner - the cosigner index
+ * @return {bitcore.HierarchicalKey}
+ */
 PrivateKey.prototype.getAll = function(receiveIndex, changeIndex, cosigner) {
-  if (typeof receiveIndex === 'undefined' || typeof changeIndex === 'undefined')
-    throw new Error('Invalid parameters');
+  preconditions.checkArgument(!_.isUndefined(receiveIndex) && !_.isUndefined(changeIndex));
 
   var ret = [];
   for (var i = 0; i < receiveIndex; i++) {
@@ -129,6 +260,4 @@ PrivateKey.prototype.getAll = function(receiveIndex, changeIndex, cosigner) {
   return ret;
 };
 
-
-
 module.exports = PrivateKey;