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Expo Crypto iconExpo Crypto

GitHub

npm

A universal library for crypto operations.

expo-crypto enables you to hash data in an equivalent manner to the Node.js core crypto API.

Platform Compatibility

Android DeviceAndroid EmulatoriOS DeviceiOS SimulatorWeb

Installation

Terminal
- npx expo install expo-crypto

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

Usage

Basic Crypto usage
import React, { 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>
  );
}

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

API

import * as Crypto from 'expo-crypto';

Methods

Crypto.digestStringAsync(algorithm, data, options)

NameTypeDescription
algorithmCryptoDigestAlgorithm

The cryptographic hash function to use to transform a block of data into a fixed-size output.

datastring

The value that will be used to generate a digest.

options
(optional)		CryptoDigestOptions

Format of the digest string. Defaults to: CryptoDigestOptions.HEX.


The digestStringAsync() method of Crypto generates a digest of the supplied data string with the provided digest algorithm. A digest is a short fixed-length value derived from some variable-length input. Cryptographic digests should exhibit collision-resistance, meaning that it's very difficult to generate multiple inputs that have equal digest values. You can specify the returned string format as one of CryptoEncoding. By default, the resolved value will be formatted as a HEX string. On web, this method can only be called from a secure origin (https) otherwise an error will be thrown.

Example

const digest = await Crypto.digestStringAsync(
  Crypto.CryptoDigestAlgorithm.SHA512,
  '🥓 Easy to Digest! 💙'
);

Returns

  • Promise<Digest>

Return a Promise which fulfills with a value representing the hashed input.

Types

CryptoDigestOptions

NameTypeDescription
encodingCryptoEncoding

Format the digest is returned in.

Digest

Type: string

Enums

CryptoDigestAlgorithm

Cryptographic hash function

CryptoDigestAlgorithm Values

Only for: 
iOS

MD2

CryptoDigestAlgorithm.MD2 ＝ "MD2"

128 bits.

Only for: 
iOS

MD4

CryptoDigestAlgorithm.MD4 ＝ "MD4"

128 bits.

Only for: 
Android
iOS

MD5

CryptoDigestAlgorithm.MD5 ＝ "MD5"

128 bits.

SHA1

CryptoDigestAlgorithm.SHA1 ＝ "SHA-1"

160 bits.

SHA256

CryptoDigestAlgorithm.SHA256 ＝ "SHA-256"

256 bits. Collision Resistant.

SHA384

CryptoDigestAlgorithm.SHA384 ＝ "SHA-384"

384 bits. Collision Resistant.

SHA512

CryptoDigestAlgorithm.SHA512 ＝ "SHA-512"

512 bits. Collision Resistant.

CryptoEncoding

CryptoEncoding Values

BASE64

CryptoEncoding.BASE64 ＝ "base64"

Has trailing padding. Does not wrap lines. Does not have a trailing newline.

HEX

CryptoEncoding.HEX ＝ "hex"

Error codes

CodeDescription
ERR_CRYPTO_UNAVAILABLEWeb Only. Access to the WebCrypto API is restricted to secure origins (https).
You can run your web project from a secure origin with expo start --https.
ERR_CRYPTO_DIGESTAn invalid encoding type provided.