中文网
🌐 Nodejs.cn
首页指南EAS参考学习

This documentation is available as Markdown for AI agents and LLMs. See the full Markdown index or append .md to any documentation URL.

This is documentation for the next SDK version. For up-to-date documentation, see the latest version (SDK 57).

Expo Crypto iconExpo Crypto

A universal library for crypto operations.

Android
iOS
tvOS
Web
Included in Expo Go

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, encryptionKey);
      const decryptedBase64 = await aesDecryptAsync(sealedData, encryptionKey, {
        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 });
  await 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.