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javascript-obfuscator

JavaScript obfuscator for Node.js

JavaScript obfuscator is a powerful free obfuscator for JavaScript and Node.js with a wide number of features which provides protection for your source code.

  • has no limits or restrictions
  • runs on your local machine - does not send data to a server;
  • compatible with es2015, es2016 and partially es2017;
  • tested on Angular2 bundle.

Online version: javascriptobfuscator.herokuapp.com

Example of obfuscated code: gist.github.com

Plugins:

npm version Build Status Coverage Status Backers on Open Collective Sponsors on Open Collective

NOTE! the README on the master branch might not match that of the latest stable release!

If this project helps you, you can support it:

⚠️ Important

Obfuscate only the code that belongs to you.

It is not recommended to obfuscate vendor scripts and polyfills, since the obfuscated code is 15-80% slower (depends on options) and the files are significantly larger.

Installation

Install the package with Yarn or NPM and add it to your devDependencies:

$ yarn add --dev javascript-obfuscator

or

$ npm install --save-dev javascript-obfuscator

Node.js usage

Here's an example of how to use it:

var JavaScriptObfuscator = require('javascript-obfuscator');
 
var obfuscationResult = JavaScriptObfuscator.obfuscate(
    `
        (function(){
            var variable1 = '5' - 3;
            var variable2 = '5' + 3;
            var variable3 = '5' + - '2';
            var variable4 = ['10','10','10','10','10'].map(parseInt);
            var variable5 = 'foo ' + 1 + 1;
            console.log(variable1);
            console.log(variable2);
            console.log(variable3);
            console.log(variable4);
            console.log(variable5);
        })();
    `,
    {
        compact: false,
        controlFlowFlattening: true
    }
);
 
console.log(obfuscationResult.getObfuscatedCode());
/*
var _0x2218 = [
    '8|3|1|2|0|4|6|9|7|5',
    'bqndd',
    'dySIh',
    'kTiiG',
    'log',
    'tuvgv'
];
(function (_0x38b423, _0x1d6bd4) {
    var _0x39a849 = function (_0x5794c7) {
        while (--_0x5794c7) {
            _0x38b423['push'](_0x38b423['shift']());
        }
    };
    _0x39a849(++_0x1d6bd4);
}(_0x2218, 0x114));
var _0x8221 = function (_0xcac13e, _0x3627d7) {
    _0xcac13e = _0xcac13e - 0x0;
    var _0x1eae4d = _0x2218[_0xcac13e];
    return _0x1eae4d;
};
(function () {
    var _0x5336d5 = {
        'bqndd': _0x8221('0x0'),
        'islRd': function _0x2abb6c(_0x2f45f8, _0x4d47b0) {
            return _0x2f45f8 + _0x4d47b0;
        },
        'kTiiG': function _0x32525a(_0x44ba8d, _0x2c5e0c) {
            return _0x44ba8d + _0x2c5e0c;
        },
        'dySIh': 'foo\x20',
        'tuvgv': function _0x28d015(_0x35d81a, _0x2d2463) {
            return _0x35d81a - _0x2d2463;
        }
    };
    var _0x5000ba = _0x5336d5[_0x8221('0x1')]['split']('|'), _0x5c972f = 0x0;
    while (!![]) {
        switch (_0x5000ba[_0x5c972f++]) {
        case '0':
            var _0x586faa = _0x5336d5['islRd'](_0x5336d5['kTiiG'](_0x5336d5[_0x8221('0x2')], 0x1), 0x1);
            continue;
        case '1':
            var _0xab6a82 = _0x5336d5[_0x8221('0x3')]('5', -'2');
            continue;
        case '2':
            var _0x19ab9d = [
                '10',
                '10',
                '10',
                '10',
                '10'
            ]['map'](parseInt);
            continue;
        case '3':
            var _0x321653 = _0x5336d5[_0x8221('0x3')]('5', 0x3);
            continue;
        case '4':
            console['log'](_0x2c1b0c);
            continue;
        case '5':
            console[_0x8221('0x4')](_0x586faa);
            continue;
        case '6':
            console[_0x8221('0x4')](_0x321653);
            continue;
        case '7':
            console[_0x8221('0x4')](_0x19ab9d);
            continue;
        case '8':
            var _0x2c1b0c = _0x5336d5[_0x8221('0x5')]('5', 0x3);
            continue;
        case '9':
            console[_0x8221('0x4')](_0xab6a82);
            continue;
        }
        break;
    }
}());
*/

obfuscate(sourceCode, options)

Returns ObfuscationResult object which contains two public methods:

  • getObfuscatedCode() - returns string with obfuscated code;
  • getSourceMap() - if sourceMap option is enabled - returns string with source map or an empty string if sourceMapMode option is set as inline.

Calling toString() for ObfuscationResult object will return string with obfuscated code.

Method takes two parameters, sourceCode and options – the source code and the opitons respectively:

  • sourceCode (string, default: null) – any valid source code, passed as a string;
  • options (Object, default: null) – an object with options.

For available options see options.

CLI usage

Usage:

javascript-obfuscator in.js [options]
javascript-obfuscator in.js --output out.js [options]

If the destination path is not specified with the --output option, obfuscated code will saved into the input file directory with name like INPUT_FILE_NAME-obfuscated.js

Examples:

javascript-obfuscator samples/sample.js --compact true --selfDefending false
// creates a new file samples/sample-obfuscated.js
 
javascript-obfuscator samples/sample.js --output output/output.js --compact true --selfDefending false
// creates a new file output/output.js

See CLI options.

JavaScript Obfuscator Options

Following options are available for the JS Obfuscator:

options:

{
    compact: true,
    controlFlowFlattening: false,
    controlFlowFlatteningThreshold: 0.75,
    deadCodeInjection: false,
    deadCodeInjectionThreshold: 0.4,
    debugProtection: false,
    debugProtectionInterval: false,
    disableConsoleOutput: false,
    log: false,
    mangle: false,
    renameGlobals: false,
    reservedNames: [],
    rotateStringArray: true,
    seed: 0,
    selfDefending: false,
    sourceMap: false,
    sourceMapBaseUrl: '',
    sourceMapFileName: '',
    sourceMapMode: 'separate',
    stringArray: true,
    stringArrayEncoding: false,
    stringArrayThreshold: 0.75,
    unicodeEscapeSequence: false
}

CLI options:

    -v, --version
    -h, --help
 
    -o, --output
 
    --compact <boolean>
    --config <string>
    --controlFlowFlattening <boolean>
    --controlFlowFlatteningThreshold <number>
    --deadCodeInjection <boolean>
    --deadCodeInjectionThreshold <number>
    --debugProtection <boolean>
    --debugProtectionInterval <boolean>
    --disableConsoleOutput <boolean>
    --log <boolean>
    --mangle <boolean>
    --renameGlobals <boolean>
    --reservedNames <list> (comma separated)
    --rotateStringArray <boolean>
    --seed <number>
    --selfDefending <boolean>
    --sourceMap <boolean>
    --sourceMapBaseUrl <string>
    --sourceMapFileName <string>
    --sourceMapMode <string> [inline, separate]
    --stringArray <boolean>
    --stringArrayEncoding <boolean|string> [truefalse, base64, rc4]
    --stringArrayThreshold <number>
    --unicodeEscapeSequence <boolean>

compact

Type: boolean Default: true

Compact code output on one line.

config

Type: string Default: ``

Name of JS/JSON config file which contains obfuscator options. These will be overridden by options passed directly to CLI

controlFlowFlattening

Type: boolean Default: false

⚠️ This option greatly affects the performance up to 1.5x slower runtime speed. Use controlFlowFlatteningThreshold to set percentage of nodes that will affected by control flow flattening.

Enables code control flow flattening. Control flow flattening is a structure transformation of the source code that hinders program comprehension.

Example:

// input
(function(){
    function foo () {
        return function () {
            var sum = 1 + 2;
            console.log(1);
            console.log(2);
            console.log(3);
            console.log(4);
            console.log(5);
            console.log(6);
        }
    }
    
    foo()();
})();
 
// output
(function () {
    function _0x3bfc5c() {
        return function () {
            var _0x3260a5 = {
                'WtABe': '4|0|6|5|3|2|1',
                'GokKo': function _0xf87260(_0x427a8e, _0x43354c) {
                    return _0x427a8e + _0x43354c;
                }
            };
            var _0x1ad4d6 = _0x3260a5['WtABe']['split']('|'), _0x1a7b12 = 0x0;
            while (!![]) {
                switch (_0x1ad4d6[_0x1a7b12++]) {
                case '0':
                    console['log'](0x1);
                    continue;
                case '1':
                    console['log'](0x6);
                    continue;
                case '2':
                    console['log'](0x5);
                    continue;
                case '3':
                    console['log'](0x4);
                    continue;
                case '4':
                    var _0x1f2f2f = _0x3260a5['GokKo'](0x1, 0x2);
                    continue;
                case '5':
                    console['log'](0x3);
                    continue;
                case '6':
                    console['log'](0x2);
                    continue;
                }
                break;
            }
        };
    }
 
    _0x3bfc5c()();
}());

controlFlowFlatteningThreshold

Type: number Default: 0.75 Min: 0 Max: 1

The probability that the controlFlowFlattening transformation will be applied to the node.

This setting is especially useful for large code size because large amounts of control flow transformations can slow down your code and increase code size.

controlFlowFlatteningThreshold: 0 equals to controlFlowFlattening: false.

deadCodeInjection

Type: boolean Default: false

⚠️ Dramatically increases size of obfuscated code (up to 200%), use only if size of obfuscated code doesn't matter. Use deadCodeInjectionThreshold to set percentage of nodes that will affected by dead code injection.
⚠️ This option forcibly enables stringArray option.

With this option random blocks of dead code will add to the obfuscated code.

Example:

// input
(function(){
    if (true) {
        var foo = function () {
            console.log('abc');
            console.log('cde');
            console.log('efg');
            console.log('hij');
        };
        
        var bar = function () {
            console.log('klm');
            console.log('nop');
            console.log('qrs');
        };
    
        var baz = function () {
            console.log('tuv');
            console.log('wxy');
            console.log('z');
        };
    
        foo();
        bar();
        baz();
    }
})();
 
// output
var _0x5024 = [
    'zaU',
    'log',
    'tuv',
    'wxy',
    'abc',
    'cde',
    'efg',
    'hij',
    'QhG',
    'TeI',
    'klm',
    'nop',
    'qrs',
    'bZd',
    'HMx'
];
var _0x4502 = function (_0x1254b1, _0x583689) {
    _0x1254b1 = _0x1254b1 - 0x0;
    var _0x529b49 = _0x5024[_0x1254b1];
    return _0x529b49;
};
(function () {
    if (!![]) {
        var _0x16c18d = function () {
            if (_0x4502('0x0') !== _0x4502('0x0')) {
                console[_0x4502('0x1')](_0x4502('0x2'));
                console[_0x4502('0x1')](_0x4502('0x3'));
                console[_0x4502('0x1')]('z');
            } else {
                console[_0x4502('0x1')](_0x4502('0x4'));
                console[_0x4502('0x1')](_0x4502('0x5'));
                console[_0x4502('0x1')](_0x4502('0x6'));
                console[_0x4502('0x1')](_0x4502('0x7'));
            }
        };
        var _0x1f7292 = function () {
            if (_0x4502('0x8') === _0x4502('0x9')) {
                console[_0x4502('0x1')](_0x4502('0xa'));
                console[_0x4502('0x1')](_0x4502('0xb'));
                console[_0x4502('0x1')](_0x4502('0xc'));
            } else {
                console[_0x4502('0x1')](_0x4502('0xa'));
                console[_0x4502('0x1')](_0x4502('0xb'));
                console[_0x4502('0x1')](_0x4502('0xc'));
            }
        };
        var _0x33b212 = function () {
            if (_0x4502('0xd') !== _0x4502('0xe')) {
                console[_0x4502('0x1')](_0x4502('0x2'));
                console[_0x4502('0x1')](_0x4502('0x3'));
                console[_0x4502('0x1')]('z');
            } else {
                console[_0x4502('0x1')](_0x4502('0x4'));
                console[_0x4502('0x1')](_0x4502('0x5'));
                console[_0x4502('0x1')](_0x4502('0x6'));
                console[_0x4502('0x1')](_0x4502('0x7'));
            }
        };
        _0x16c18d();
        _0x1f7292();
        _0x33b212();
    }
}());

deadCodeInjectionThreshold

Type: number Default: 0.4 Min: 0 Max: 1

Allows to set percentage of nodes that will affected by deadCodeInjection.

debugProtection

Type: boolean Default: false

⚠️ Can freeze your browser if you open the Developer Tools.

This option makes it almost impossible to use the console tab of the Developer Tools (both on WebKit-based and Mozilla Firefox).

  • WebKit-based: blocks the site window, but you still can navigate through Developer Tools panel.
  • Firefox: does not block the site window, but still won't let you use DevTools.

debugProtectionInterval

Type: boolean Default: false

⚠️ Can freeze your browser! Use at own risk.

If checked, an interval is used to force the debug mode on the Console tab, making it harder to use other features of the Developer Tools. Works if debugProtection is enabled.

disableConsoleOutput

Type: boolean Default: false

Disables the use of console.log, console.info, console.error, console.warn, console.debug, console.exception and console.trace by replacing them with empty functions. This makes the use of the debugger harder.

domainLock

Type: string[] Default: []

Locks the obfuscated source code so it only runs on specific domains and/or sub-domains. This makes really hard for someone just copy and paste your source code and run elsewhere.

Multiple domains and sub-domains

It's possible to lock your code to more than one domain or sub-domain. For instance, to lock it so the code only runs on www.example.com add www.example.com, to make it work on any sub-domain from example.com, use .example.com.

log

Type: boolean Default: false

Enables logging of the information to the console.

mangle

Type: boolean Default: false

Enables mangling of variable names.

renameGlobals

Type: boolean Default: false

⚠️ this option can break your code. Enable it only if you know what it does!

Enables obfuscation of global variable and function names with declaration.

reservedNames

Type: string[] Default: []

Disables the obfuscation of variables names, function names and function parameters that match the Regular Expression used.

Example:

    {
        reservedNames: [
            '^someVariable',
            'functionParameter_\d'
        ]
    }

rotateStringArray

Type: boolean Default: true

⚠️ stringArray must be enabled

Shift the stringArray array by a fixed and random (generated at the code obfuscation) places. This makes it harder to match the order of the removed strings to their original place.

This option is recommended if your original source code isn't small, as the helper function can attract attention.

seed

Type: number Default: 0

This option sets seed for random generator. This is useful for creating repeatable results.

If seed is 0 - random generator will work without seed.

selfDefending

Type: boolean Default: false

⚠️ Don't change obfuscated code in any way after obfuscation with this option, because any change like uglifying of code can trigger self defending and code wont work anymore!
⚠️ This option forcibly sets compact value to true

This option makes the output code resilient against formatting and variable renaming. If one tries to use a JavaScript beautifier on the obfuscated code, the code won't work anymore, making it harder to understand and modify it.

sourceMap

Type: boolean Default: false

Enables source map generation for obfuscated code.

Source maps can be useful to help you debug your obfuscated JavaScript source code. If you want or need to debug in production, you can upload the separate source map file to a secret location and then point your browser there.

sourceMapBaseUrl

Type: string Default: ``

Sets base url to the source map import url when sourceMapMode: 'separate'.

CLI example:

javascript-obfuscator input.js --output out.js --sourceMap true --sourceMapBaseUrl 'http://localhost:9000'

Result:

//# sourceMappingURL=http://localhost:9000/out.js.map

sourceMapFileName

Type: string Default: ``

Sets file name for output source map when sourceMapMode: 'separate'.

CLI example:

javascript-obfuscator input.js --output out.js --sourceMap true --sourceMapBaseUrl 'http://localhost:9000' --sourceMapFileName example

Result:

//# sourceMappingURL=http://localhost:9000/example.js.map

sourceMapMode

Type: string Default: separate

Specifies source map generation mode:

  • inline - emit a single file with source maps instead of having a separate file;
  • separate - generates corresponding '.map' file with source map. In case you run obfuscator through CLI - adds link to source map file to the end of file with obfuscated code //# sourceMappingUrl=file.js.map.

stringArray

Type: boolean Default: true

Removes string literals and place them in a special array. For instance, the string "Hello World" in var m = "Hello World"; will be replaced with something like var m = _0x12c456[0x1];

stringArrayEncoding

Type: boolean|string Default: false

⚠️ stringArray option must be enabled

This option can slightly slow down your script.

Encode all string literals of the stringArray using base64 or rc4 and inserts a special code that used to decode it back at runtime.

Available values:

  • true (boolean): encode stringArray values using base64
  • false (boolean): don't encode stringArray values
  • 'base64' (string): encode stringArray values using base64
  • 'rc4' (string): encode stringArray values using rc4. About 30-50% slower than base64, but more harder to get initial values. It is recommended to disable unicodeEscapeSequence option with rc4 encoding to prevent very large size of obfuscated code.

stringArrayThreshold

Type: number Default: 0.8 Min: 0 Max: 1

⚠️ stringArray option must be enabled

You can use this setting to adjust the probability (from 0 to 1) that a string literal will be inserted into the stringArray.

This setting is especially useful for large code size because it repeatedly calls to the string array and can slow down your code.

stringArrayThreshold: 0 equals to stringArray: false.

unicodeEscapeSequence

Type: boolean Default: false

Allows to enable/disable string conversion to unicode escape sequence.

Unicode escape sequence increases code size greatly and strings easily can be reverted to their original view. Recommended to enable this option only for small source code.

Preset Options

High obfuscation, low performance

Performance will 50-100% slower than without obfuscation

{
    compact: true,
    controlFlowFlattening: true,
    controlFlowFlatteningThreshold: 1,
    deadCodeInjection: true,
    deadCodeInjectionThreshold: 1,
    debugProtection: true,
    debugProtectionInterval: true,
    disableConsoleOutput: true,
    log: false,
    mangle: false,
    renameGlobals: false,
    rotateStringArray: true,
    selfDefending: true,
    stringArray: true,
    stringArrayEncoding: 'rc4',
    stringArrayThreshold: 1,
    unicodeEscapeSequence: false
}

Medium obfuscation, optimal performance

Performance will 30-35% slower than without obfuscation

{
    compact: true,
    controlFlowFlattening: true,
    controlFlowFlatteningThreshold: 0.75,
    deadCodeInjection: true,
    deadCodeInjectionThreshold: 0.4,
    debugProtection: false,
    debugProtectionInterval: false,
    disableConsoleOutput: true,
     log: false,
    mangle: false,
    renameGlobals: false,
    rotateStringArray: true,
    selfDefending: true,
    stringArray: true,
    stringArrayEncoding: 'base64',
    stringArrayThreshold: 0.75,
    unicodeEscapeSequence: false
}

Low obfuscation, High performance

Performance will slightly slower than without obfuscation

{
    compact: true,
    controlFlowFlattening: false,
    deadCodeInjection: false,
    debugProtection: false,
    debugProtectionInterval: false,
    disableConsoleOutput: true,
     log: false,
    mangle: true,
    renameGlobals: false,
    rotateStringArray: true,
    selfDefending: true,
    stringArray: true,
    stringArrayEncoding: false,
    stringArrayThreshold: 0.75,
    unicodeEscapeSequence: false
}

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Sponsors

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License

Copyright (C) 2017 Timofey Kachalov.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.