Issue 4878 - Start using ESLint for adblockpluscore

lib/rsa.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-/* globals atob, console */
+/* global console */
 
 "use strict";
 
 /**
  * This is a specialized RSA library meant only to verify SHA1-based signatures.
  */
 
-let {BigInteger} = require("jsbn");
-let Rusha = require("rusha");
+const {BigInteger} = require("jsbn");
+const Rusha = require("rusha");
 
 let rusha = new Rusha();
 
 // Define ASN.1 templates for the data structures used
 function seq(...args)
 {
   return {type: 0x30, children: args};
 }
 function obj(id)
 {
@@ skipping 24 matching lines @@
 let signatureTemplate = seq(
   seq(obj("\x2B\x0E\x03\x02\x1A"), {}),
   octetResult("sha1")
 );
 
 /**
  * Reads ASN.1 data matching the template passed in. This will throw an
  * exception if the data format doesn't match the template. On success an
  * object containing result properties is returned.
  * @see http://luca.ntop.org/Teaching/Appunti/asn1.html for info on the format.
- * @param {String} data
+ * @param {string} data
  * @param {Object} templ
  * @returns {Object}
  */
 function readASN1(data, templ)
 {
   let pos = 0;
   function next()
   {
     return data.charCodeAt(pos++);
   }
@@ skipping 53 matching lines @@
   let out = {};
   readNode(templ);
   if (pos != data.length)
     throw "Too much data";
   return out;
 }
 
 /**
  * Reads a BER-encoded RSA public key. On success returns an object with the
  * properties n and e (the components of the key), otherwise null.
- * @param {String} key
- * @return {Object|null}
+ * @param {string} key
+ * @return {?Object}
  */
 function readPublicKey(key)
 {
   try
   {
     return readASN1(atob(key), publicKeyTemplate);
   }
   catch (e)
   {
     console.warn("Invalid RSA public key: " + e);
     return null;
   }
 }
 
 /**
  * Checks whether the signature is valid for the given public key and data.
- * @param {String} key
- * @param {String} signature
- * @param {String} data
- * @return {Boolean}
+ * @param {string} key
+ * @param {string} signature
+ * @param {string} data
+ * @return {boolean}
  */
 function verifySignature(key, signature, data)
 {
   let keyData = readPublicKey(key);
   if (!keyData)
     return false;
 
   // We need the exponent as regular number
   keyData.e = parseInt(keyData.e.toString(16), 16);
 
   // Decrypt signature data using RSA algorithm
   let sigInt = new BigInteger(atob(signature), 256);
   let digest = sigInt.modPowInt(keyData.e, keyData.n).toString(256);
 
   try
   {
     let pos = 0;
     let next = () => digest.charCodeAt(pos++);
 
     // Skip padding, see http://tools.ietf.org/html/rfc3447#section-9.2 step 5
     if (next() != 1)
       throw "Wrong padding in signature digest";
-    while (next() == 255)
-    {
-      // Empty
-    }
+    while (next() == 255) {}
     if (digest.charCodeAt(pos - 1) != 0)
       throw "Wrong padding in signature digest";
 
     // Rest is an ASN.1 structure, get the SHA1 hash from it and compare to
     // the real one
     let {sha1} = readASN1(digest.substr(pos), signatureTemplate);
     let expected = new BigInteger(rusha.digest(data), 16);
     return (sha1.compareTo(expected) == 0);
   }
   catch (e)
   {
     console.warn("Invalid encrypted signature: " + e);
     return false;
   }
 }
 exports.verifySignature = verifySignature;