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Original file line number | Diff line number | Diff line change |
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@@ -1,160 +1,94 @@ | ||
const Int64 = require('node-int64'); | ||
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let Stream = require('stream'); | ||
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const Int64 = require("node-int64"); | ||
let Stream = require("stream"); | ||
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// Backwards compatibility for node versions < 8 | ||
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if (!Stream.Writable || !Stream.Writable.prototype.destroy) | ||
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Stream = require('readable-stream'); | ||
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Stream = require("readable-stream"); | ||
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let table; | ||
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function generateTable() { | ||
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const poly = 0xEDB88320; | ||
let c, n, k; | ||
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table = []; | ||
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for (n = 0; n < 256; n++) { | ||
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c = n; | ||
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for (k = 0; k < 8; k++) | ||
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c = (c & 1) ? poly ^ (c >>> 1) : c = c >>> 1; | ||
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for (k = 0; k < 8; k++) c = c & 1 ? poly ^ (c >>> 1) : (c = c >>> 1); | ||
table[n] = c >>> 0; | ||
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} | ||
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} | ||
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function crc(ch, crc) { | ||
if (!table) generateTable(); | ||
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if (!table) | ||
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generateTable(); | ||
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if (ch.charCodeAt) | ||
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ch = ch.charCodeAt(0); | ||
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if (ch.charCodeAt) ch = ch.charCodeAt(0); | ||
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const l = (crc.readUInt32BE() >> 8) & 0xffffff; | ||
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const r = table[(crc.readUInt32BE() ^ (ch >>> 0)) & 0xff]; | ||
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return (l ^ r) >>> 0; | ||
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} | ||
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function multiply(a, b) { | ||
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const ah = (a >> 16) & 0xffff; | ||
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const al = a & 0xffff; | ||
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const bh = (b >> 16) & 0xffff; | ||
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const bl = b & 0xffff; | ||
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const high = (ah * bl + al * bh) & 0xffff; | ||
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return ((high << 16) >>> 0) + al * bl; | ||
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}; | ||
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} | ||
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function Decrypt() { | ||
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if (!(this instanceof Decrypt)) | ||
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return new Decrypt(); | ||
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if (!(this instanceof Decrypt)) return new Decrypt(); | ||
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this.key0 = Buffer.allocUnsafe(4); | ||
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this.key1 = Buffer.allocUnsafe(4); | ||
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this.key2 = Buffer.allocUnsafe(4); | ||
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this.key0.writeUInt32BE(0x12345678, 0); | ||
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this.key1.writeUInt32BE(0x23456789, 0); | ||
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this.key2.writeUInt32BE(0x34567890, 0); | ||
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} | ||
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Decrypt.prototype.update = function(h) { | ||
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Decrypt.prototype.update = function (h) { | ||
this.key0.writeUInt32BE(crc(h, this.key0)); | ||
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this.key1.writeUInt32BE(((this.key0.readUInt32BE() & 0xff & 0xFFFFFFFF) + this.key1.readUInt32BE()) >>> 0); | ||
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const x = new Int64((multiply(this.key1.readUInt32BE(), 134775813) + 1) & 0xFFFFFFFF); | ||
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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); | ||
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x.copy(b, 0); | ||
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b.copy(this.key1, 0, 4, 8); | ||
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this.key2.writeUInt32BE(crc(((this.key1.readUInt32BE() >> 24) & 0xff) >>> 0, this.key2)); | ||
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this.key2.writeUInt32BE( | ||
crc(((this.key1.readUInt32BE() >> 24) & 0xff) >>> 0, this.key2) | ||
); | ||
}; | ||
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Decrypt.prototype.decryptByte = function(c) { | ||
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Decrypt.prototype.decryptByte = function (c) { | ||
const k = (this.key2.readUInt32BE() | 2) >>> 0; | ||
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c = c ^ ((multiply(k, (k^1 >>> 0)) >> 8) & 0xff); | ||
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c = c ^ ((multiply(k, (k ^ 1 >>> 0)) >> 8) & 0xff); | ||
this.update(c); | ||
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return c; | ||
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}; | ||
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Decrypt.prototype.stream = function() { | ||
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Decrypt.prototype.stream = function () { | ||
const stream = Stream.Transform(), | ||
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self = this; | ||
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stream._transform = function(d, e, cb) { | ||
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for (let i = 0; i<d.length; i++) { | ||
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stream._transform = function (d, e, cb) { | ||
for (let i = 0; i < d.length; i++) { | ||
d[i] = self.decryptByte(d[i]); | ||
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} | ||
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this.push(d); | ||
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cb(); | ||
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}; | ||
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return stream; | ||
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}; | ||
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module.exports = Decrypt; |
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