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2 changes: 2 additions & 0 deletions index.d.ts
Original file line number Diff line number Diff line change
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import React from 'react'
export default class PolyfillCrypto extends React.Component {}
115 changes: 115 additions & 0 deletions index.js
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require('react-native-get-random-values')

const React = require('react')
const { StyleSheet, View, WebView } = require('react-native')
const { MainWorker, webViewWorkerString } = require('webview-crypto')
const encodeUtf8 = require('encode-utf8')
const encodeBase64 = require('fast-base64-encode')

/**
* @param {string} input
*/
function base64EncodeString (input) {
return encodeBase64(new Uint8Array(encodeUtf8(input)))
}

const styles = StyleSheet.create({
hide: {
display: 'none',
position: 'absolute',

width: 0,
height: 0,

flexGrow: 0,
flexShrink: 1
}
})

const internalLibrary = `
(function () {
function postMessage (message) {
if (window.postMessage.length !== 1) {
setTimeout(postMessage, 200, message)
} else {
window.postMessage(JSON.stringify(message))
}
}

var wvw = new WebViewWorker(postMessage)
window.document.addEventListener('message', (e) => wvw.onMainMessage(e.data))
}())
`

let resolveWorker
let workerPromise = new Promise(resolve => { resolveWorker = resolve })

function sendToWorker (message) {
console.warn(message)
workerPromise.then(worker => worker.onWebViewMessage(message))
}

const subtle = {
decrypt (...args) { return workerPromise.then(worker => worker.crypto.subtle.decrypt(...args)) },
deriveKey (...args) { return workerPromise.then(worker => worker.crypto.subtle.deriveKey(...args)) },
digest (...args) { return workerPromise.then(worker => worker.crypto.subtle.digest(...args)) },
encrypt (...args) { return workerPromise.then(worker => worker.crypto.subtle.encrypt(...args)) },
exportKey (...args) { return workerPromise.then(worker => worker.crypto.subtle.exportKey(...args)) },
generateKey (...args) { return workerPromise.then(worker => worker.crypto.subtle.generateKey(...args)) },
importKey (...args) { return workerPromise.then(worker => worker.crypto.subtle.importKey(...args)) },
sign (...args) { return workerPromise.then(worker => worker.crypto.subtle.sign(...args)) },
unwrapKey (...args) { return workerPromise.then(worker => worker.crypto.subtle.unwrapKey(...args)) },
verify (...args) { return workerPromise.then(worker => worker.crypto.subtle.verify(...args)) },
wrapKey (...args) { return workerPromise.then(worker => worker.crypto.subtle.wrapKey(...args)) }
}

class PolyfillCrypto extends React.Component {
constructor (props) {
super(props)
this.webViewRef = React.createRef()
}

shouldComponentUpdate () {
return false
}

componentDidMount () {
const webView = this.webViewRef.current

console.warn('CREATING MAIN WORKER')

resolveWorker(new MainWorker((msg) => { console.warn(msg); webView.postMessage(msg) }))
}

render () {
// The uri 'about:blank' doesn't have access to crypto.subtle
const uri = 'file:///android_asset/blank.html'

// Base64 dance is to work around https://github.com/facebook/react-native/issues/20365
const code = `((function () {${webViewWorkerString};${internalLibrary}})())`
const injectString = `eval(window.atob('${base64EncodeString(code)}'))`

const webView = React.createElement(WebView, {
injectedJavaScript: injectString,
javaScriptEnabled: true,
mixedContentMode: 'compatibility',
onError: (a) => console.error(a),
onMessage: (ev) => sendToWorker(ev.nativeEvent.data),
ref: this.webViewRef,
source: { uri }
})

return React.createElement(View, { style: styles.hide }, webView)
}
}

if (typeof global.crypto !== 'object') {
global.crypto = {}
}

if (typeof global.crypto.subtle !== 'object') {
global.crypto.subtle = subtle
}

Object.defineProperty(exports, '__esModule', { value: true })
exports.default = PolyfillCrypto
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