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Expo Crypto iconExpo Crypto

A universal library for crypto operations.

Android
iOS
tvOS
Web
Included in Expo Go
Recommended version:
~56.0.5

expo-crypto enables you to hash data in an equivalent manner to the Node.js core crypto API, and perform crypto operations such as AES encryption and decryption.

Installation

Terminal
- npx expo install expo-crypto
- yarn expo install expo-crypto
- pnpm expo install expo-crypto
- bun expo install expo-crypto

If you are installing this in an existing React Native app, make sure to install expo in your project.

Usage

Basic Crypto usage
import { useEffect } from 'react';
import { StyleSheet, View, Text } from 'react-native';
import * as Crypto from 'expo-crypto';

export default function App() {
  useEffect(() => {
    (async () => {
      const digest = await Crypto.digestStringAsync(
        Crypto.CryptoDigestAlgorithm.SHA256,
        'GitHub stars are neat 🌟'
      );
      console.log('Digest: ', digest);
      /* Some crypto operation... */
    })();
  }, []);

  return (
    <View style={styles.container}>
      <Text>Crypto Module Example</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

AES encryption and decryption

Simple encryption / decryption
import { useEffect } from 'react';
import { StyleSheet, View, Text } from 'react-native';
import { AESEncryptionKey, aesEncryptAsync, aesDecryptAsync } from 'expo-crypto';

export default function App() {
  useEffect(() => {
    (async () => {
      const plaintext = 'Hello, world!';
      const plaintextBase64 = btoa(plaintext);

      const encryptionKey = await AESEncryptionKey.generate();
      const sealedData = await aesEncryptAsync(plaintextBase64, key);
      const decryptedBase64 = await aesDecryptAsync(sealedData, key, {
        output: 'base64',
      });

      const decrypted = atob(decryptedBase64);
      console.log('Decrypted: ', decrypted);
    })();
  }, []);

  return (
    <View style={styles.container}>
      <Text>Crypto Module Example</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});
Encrypt data and save it to the file
example.ts
import { AESEncryptionKey, aesEncryptAsync } from 'expo-crypto';
import { File, Paths } from 'expo-file-system';
import * as SecureStore from 'expo-secure-store';

async function encryptAndSaveData(plaintextData: Uint8Array) {
  // Generate encryption key
  const encryptionKey = await AESEncryptionKey.generate();

  // Encrypt data
  const sealedData = await aesEncryptAsync(plaintextData, encryptionKey);
  const encryptedBytes = await sealedData.combined();

  // Store encryption key
  const keyHex = await encryptionKey.encoded('hex');
  await SecureStore.setItemAsync('aes-encryption-key', keyHex);

  // Save encrypted file
  const file = new File(Paths.cache, 'encrypted.dat');
  file.create({ overwrite: true });
  file.write(encryptedBytes);
}
Load file and decrypt data
example.ts
import { AESEncryptionKey, AESSealedData, aesDecryptAsync } from 'expo-crypto';
import { File, Paths } from 'expo-file-system';
import * as SecureStore from 'expo-secure-store';

async function loadAndDecryptData(): Promise<Uint8Array | null> {
  // Load encryption key
  const keyHex = await SecureStore.getItemAsync('aes-encryption-key');
  if (!keyHex) {
    return null;
  }
  const encryptionKey = await AESEncryptionKey.import(keyHex, 'hex');

  // Load encrypted file
  const file = new File(Paths.cache, 'encrypted.dat');
  if (!file.exists) {
    return null;
  }
  const encryptedBytes = await file.bytes();
  const sealedData = AESSealedData.fromCombined(encryptedBytes);

  // Decrypt data
  const plaintextBytes = await aesDecryptAsync(data, encryptionKey);
  return plaintextBytes;
}

API

import * as Crypto from 'expo-crypto';

No API data file found, sorry!

Error codes

CodeDescription
ERR_CRYPTO_UNAVAILABLEWeb Only. Access to the WebCrypto API is restricted to secure origins (localhost/https).
ERR_CRYPTO_DIGESTAn invalid encoding type provided.