Encrypt in Node and Decrypt in React-Native (the reverse is almost identical)

encrypt-decrypt-react-native-node.js

// The purpose of this is that there was as cipher vulnerability found in the javascript implementation of the main 
//. crypto-js library.
//. The native implementation they created made it unusable on react-native
//  The reason we are using the node version of crypto is because the only supported AES from the react-native 
//. implementation is aes-128-cbc
//. The node crypto library seems to be the only lib that supports that specific version.

// requires installing - https://www.npmjs.com/package/react-native-simple-crypto also linking
import RNSimpleCrypto from 'react-native-simple-crypto'
const toUtf8 = RNSimpleCrypto.utils.convertArrayBufferToUtf8


function decrypt(hexString){
  const key = RNSimpleCrypto.utils.convertHexToArrayBuffer(SECRET)
  const iv = RNSimpleCrypto.utils.convertHexToArrayBuffer(IV_HEX)

  const token = RNSimpleCrypto.utils.convertHexToArrayBuffer(hexString)
  return RNSimpleCrypto.AES.decrypt(token, key, iv)
}

// In node file, send the excrpytedToken 'over-the-wire'
function encrypt(aString) {
  try {
    const iv = new Buffer(IV_HEX, 'hex')
    const key = new Buffer(SECRET, 'hex')
    const encryptedBuffer = new Buffer(token)
    // This is the only supported algorithm for AES for the react-native library
    const cipher = crypto.createCipheriv('aes-128-cbc', key, iv)
    const chunks = [cipher.update(encryptedBuffer, 'buffer', 'hex'), cipher.final('hex')]
    const encryptedToken = chunks.join('')
    
    return encryptedToken
    } catch (e) {
      // do something
    }
}