Merge pull request #316 from lechuhuuha/master

replace bigint with node-int64

lib/Decrypt.js

@@ -1,5 +1,10 @@
-const bigInt = require('big-integer');
-const Stream = require('stream');
+const Int64 = require("node-int64");
+let Stream = require("stream");
+
+// Backwards compatibility for node versions < 8
+
+if (!Stream.Writable || !Stream.Writable.prototype.destroy)
+  Stream = require("readable-stream");
 
 let table;
 
@@ -9,59 +14,81 @@ function generateTable() {
   table = [];
   for (n = 0; n < 256; n++) {
     c = n;
-    for (k = 0; k < 8; k++)
-      c = (c & 1) ? poly ^ (c >>> 1) : c = c >>> 1;
+    for (k = 0; k < 8; k++) c = c & 1 ? poly ^ (c >>> 1) : (c = c >>> 1);
     table[n] = c >>> 0;
   }
 }
 
 function crc(ch, crc) {
-  if (!table)
-    generateTable();
+  if (!table) generateTable();
+
+  if (ch.charCodeAt) ch = ch.charCodeAt(0);
+
+  const l = (crc.readUInt32BE() >> 8) & 0xffffff;
+  const r = table[(crc.readUInt32BE() ^ (ch >>> 0)) & 0xff];
+
+  return (l ^ r) >>> 0;
+}
 
-  if (ch.charCodeAt)
-    ch = ch.charCodeAt(0);
+function multiply(a, b) {
+  const ah = (a >> 16) & 0xffff;
+  const al = a & 0xffff;
+  const bh = (b >> 16) & 0xffff;
+  const bl = b & 0xffff;
+  const high = (ah * bl + al * bh) & 0xffff;
 
-  return (bigInt(crc).shiftRight(8).and(0xffffff)).xor(table[bigInt(crc).xor(ch).and(0xff)]).value;
+  return ((high << 16) >>> 0) + al * bl;
 }
 
 function Decrypt() {
-  if (!(this instanceof Decrypt))
-    return new Decrypt();
+  if (!(this instanceof Decrypt)) return new Decrypt();
 
-  this.key0 = 305419896;
-  this.key1 = 591751049;
-  this.key2 = 878082192;
+  this.key0 = Buffer.allocUnsafe(4);
+  this.key1 = Buffer.allocUnsafe(4);
+  this.key2 = Buffer.allocUnsafe(4);
+
+  this.key0.writeUInt32BE(0x12345678, 0);
+  this.key1.writeUInt32BE(0x23456789, 0);
+  this.key2.writeUInt32BE(0x34567890, 0);
 }
 
-Decrypt.prototype.update = function(h) {
-  this.key0 = crc(h, this.key0);
-  this.key1 = bigInt(this.key0).and(255).and(4294967295).add(this.key1);
-  this.key1 = bigInt(this.key1).multiply(134775813).add(1).and(4294967295).value;
-  this.key2 = crc(bigInt(this.key1).shiftRight(24).and(255), this.key2);
+Decrypt.prototype.update = function (h) {
+  this.key0.writeUInt32BE(crc(h, this.key0));
+  this.key1.writeUInt32BE(
+    ((this.key0.readUInt32BE() & 0xff & 0xFFFFFFFF) +
+      this.key1.readUInt32BE()) >>> 0
+  );
+  const x = new Int64(
+    (multiply(this.key1.readUInt32BE(), 134775813) + 1) & 0xFFFFFFFF
+  );
+  const b = Buffer.alloc(8);
+  x.copy(b, 0);
+  b.copy(this.key1, 0, 4, 8);
+  this.key2.writeUInt32BE(
+    crc(((this.key1.readUInt32BE() >> 24) & 0xff) >>> 0, this.key2)
+  );
 };
 
-
-Decrypt.prototype.decryptByte = function(c) {
-  const k = bigInt(this.key2).or(2);
-  c = c ^ bigInt(k).multiply(bigInt(k^1)).shiftRight(8).and(255);
+Decrypt.prototype.decryptByte = function (c) {
+  const k = (this.key2.readUInt32BE() | 2) >>> 0;
+  c = c ^ ((multiply(k, (k ^ 1 >>> 0)) >> 8) & 0xff);
   this.update(c);
+
   return c;
 };
 
-Decrypt.prototype.stream = function() {
+Decrypt.prototype.stream = function () {
   const stream = Stream.Transform(),
     self = this;
-
-  stream._transform = function(d, e, cb) {
-    for (let i = 0; i<d.length;i++) {
+  stream._transform = function (d, e, cb) {
+    for (let i = 0; i < d.length; i++) {
       d[i] = self.decryptByte(d[i]);
     }
     this.push(d);
     cb();
   };
+
   return stream;
 };
 
-
 module.exports = Decrypt;

package.json

@@ -23,11 +23,11 @@
   },
   "license": "MIT",
   "dependencies": {
-    "big-integer": "^1.6.17",
     "bluebird": "~3.4.1",
     "duplexer2": "~0.1.4",
     "fs-extra": "^11.2.0",
-    "graceful-fs": "^4.2.2"
+    "graceful-fs": "^4.2.2",
+    "node-int64": "^0.4.0"
   },
   "devDependencies": {
     "@eslint/js": "^9.2.0",