How to obfuscate code in react-native for IOS

Question

I have been trying to obfuscate the code for a while by using react-native-obfuscating-transformer. Everything seems okay but when I check the bundle.js. I can't see any obfuscated code.

PS: Currently, I try only for IOS.

Here are my config files.

metro.config.js


module.exports = {
    transformer: {
        babelTransformerPath: require.resolve('./transformer'),
        getTransformOptions: async () => ({
            transform: {
                experimentalImportSupport: false,
                inlineRequires: false,
            },
        }),
    },
};

transformer.js

const obfuscatingTransformer = require('react-native-obfuscating-transformer');

module.exports = obfuscatingTransformer({
    upstreamTransformer: require('metro-react-native-babel-transformer'),
    enableInDevelopment: true,
    obfuscatorOptions: {
        compact: true,
        controlFlowFlattening: true,
        controlFlowFlatteningThreshold: 0.75,
        deadCodeInjection: true,
        deadCodeInjectionThreshold: 0.4,
        debugProtection: false,
        debugProtectionInterval: false,
        disableConsoleOutput: true,
        identifierNamesGenerator: 'hexadecimal',
        log: false,
        numbersToExpressions: true,
        renameGlobals: false,
        rotateStringArray: true,
        selfDefending: true,
        shuffleStringArray: true,
        simplify: true,
        splitStrings: true,
        splitStringsChunkLength: 10,
        stringArray: true,
        stringArrayEncoding: ['base64'],
        stringArrayWrappersCount: 2,
        stringArrayWrappersChainedCalls: true,
        stringArrayWrappersType: 'variable',
        stringArrayThreshold: 0.75,
        transformObjectKeys: true,
        unicodeEscapeSequence: false,
    },
});

Muhammad Numan · Accepted Answer · 2023-03-30 12:01:48Z

4

+50

I finally figured out how to make it work after several test.

my react and react native version:

 "react": "16.9.0",
 "react-native": "0.61.5",

install other dependencies needed:

npm install babylon --save
npm install --save babel-traverse

transformer.js

const obfuscatingTransformer = require("react-native-obfuscating-transformer")
const filter = filename => { 
  return filename.startsWith("src");
};

module.exports = obfuscatingTransformer({
// this configuration is based on https://github.com/javascript-obfuscator/javascript-obfuscator
  obfuscatorOptions:{
    compact: true,
    controlFlowFlattening: false,
    deadCodeInjection: false,
    debugProtection: false,
    debugProtectionInterval: false,
    disableConsoleOutput: true,
    identifierNamesGenerator: 'hexadecimal',
    log: false,
    renameGlobals: false,
    rotateStringArray: true,
    selfDefending: true,
    shuffleStringArray: true,
    splitStrings: false,
    stringArray: true,
    stringArrayEncoding: ['base64'],
    stringArrayThreshold: 0.75,
    unicodeEscapeSequence: false
  },
  upstreamTransformer: require('metro-react-native-babel-transformer'),
  emitObfuscatedFiles: false,
  enableInDevelopment: true,
  filter: filter,
  trace: true
})

metro.config.js

module.exports = {
  transformer: {
    getTransformOptions: async () => ({
      transform: {
        experimentalImportSupport: false,
        inlineRequires: false,
      },
    }),
    babelTransformerPath: require.resolve("./transformer")   // add here the transformer.js
  },
};

NOTE:

set emitObfuscatedFiles to true in obfuscatorOptions to emit the obfuscated versions of files alongside their originals, for comparison.

If you're building in release, you can also compare the generated index.android.bundle (located in \android\app\build\generated\assets\react\release) with and without using the react-native-obfuscating-transformer using online diff tool to see the difference

edited Mar 30, 2023 at 12:01

answered Oct 14, 2020 at 6:06

Muhammad Numan

25.6k8 gold badges74 silver badges99 bronze badges

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9 Comments

Halil İbrahim Özdoğan Over a year ago

Thanks for the very clear explanation. Code obfuscation looks like working well but app crashes. I got exaclty same error with this guy github.com/javascript-obfuscator/…

Muhammad Numan Over a year ago

@HalilİbrahimÖzdoğan can you tell me your nodejs version and react-native-obfuscating-transformer version?

Halil İbrahim Özdoğan Over a year ago

I am grateful to you for being helpful. Removing package-lock.json and node_modules didn't fix the problem. But I changed forked the project and changed the version of javascript-obfuscator dependency. Right now, it's working well. Since your solution helped me, indeed. I am going to mark this answer.

Jay Thummar Over a year ago

Obfuscating src\screens\helloWorld.js error src\screens\helloWorld.js: function (prevType) { this.state.exprAllowed = false; if (prevType === types._let || prevType === types._c...<omitted>... } could not be cloned. Error: function (prevType) { this.state.exprAllowed = false; if (prevType === types._let || prevType === types._c...<omitted>... } could not be cloned. andy idea how to solve it ?

Muhammad Numan Over a year ago

@instanceof you can use beyondcompare tool for two file

|

Alex · Accepted Answer · 2021-01-31 16:59:01Z

4

I was not able to get my js code obfuscated with this method, but I think I managed to do it with this package. I am interested in hearing your opinions. https://www.npmjs.com/package/obfuscator-io-metro-plugin

answered Jan 31, 2021 at 16:59

Alex

411 bronze badge

2 Comments

Alex Over a year ago

Basically everything @Muhammad Numan did. I think it might have not choosen the right folder to obfuscate (even though I filtered the folder), but I really am nor sure. The metro plugin works perfectly though :)

azdeviz Over a year ago

Agree bro, this plugin is better check npmtrends.com/@heroai/… it has been updated last two months ago

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