This is documentation for the next SDK version. For up-to-date documentation, see the latest version (SDK 52).
Expo CryptoA universal library for crypto operations.
expo-crypto enables you to hash data in an equivalent manner to the Node.js core crypto API.
Installation
- npx expo install expo-cryptoIf you are installing this in an existing React Native app, start by installing expo in your project. Then, follow the additional instructions as mentioned by the library's README under "Installation in bare React Native projects" section.
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',
},
});
API
import * as Crypto from 'expo-crypto';
Methods
Crypto.digest(algorithm, data)
| Parameter | Type | Description |
|---|---|---|
| algorithm | CryptoDigestAlgorithm | The cryptographic hash function to use to transform a block of data into a fixed-size output. |
| data | BufferSource | The value that will be used to generate a digest. |
The digest() method of Crypto generates a digest of the supplied TypedArray of bytes data 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.
On web, this method can only be called from a secure origin (HTTPS) otherwise, an error will be thrown.
A Promise which fulfills with an ArrayBuffer representing the hashed input.
Example
const array = new Uint8Array([1, 2, 3, 4, 5]);
const digest = await Crypto.digest(Crypto.CryptoDigestAlgorithm.SHA512, array);
console.log('Your digest: ' + digest);
Crypto.digestStringAsync(algorithm, data, options)
| Parameter | Type | Description |
|---|---|---|
| algorithm | CryptoDigestAlgorithm | The cryptographic hash function to use to transform a block of data into a fixed-size output. |
| data | string | The value that will be used to generate a digest. |
| options (optional) | CryptoDigestOptions | Format of the digest string. Defaults to: |
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.
Return a Promise which fulfills with a value representing the hashed input.
Example
const digest = await Crypto.digestStringAsync(
Crypto.CryptoDigestAlgorithm.SHA512,
'🥓 Easy to Digest! 💙'
);
Crypto.getRandomBytes(byteCount)
| Parameter | Type | Description |
|---|---|---|
| byteCount | number | A number within the range from |
Generates completely random bytes using native implementations. The byteCount property
is a number indicating the number of bytes to generate in the form of a Uint8Array.
Falls back to Math.random during development to prevent issues with React Native Debugger.
An array of random bytes with the same length as the byteCount.
Crypto.getRandomBytesAsync(byteCount)
| Parameter | Type | Description |
|---|---|---|
| byteCount | number | A number within the range from |
Generates completely random bytes using native implementations. The byteCount property
is a number indicating the number of bytes to generate in the form of a Uint8Array.
A promise that fulfills with an array of random bytes with the same length as the byteCount.
Crypto.getRandomValues(typedArray)
| Parameter | Type | Description |
|---|---|---|
| typedArray | T | An integer based |
The getRandomValues() method of Crypto fills a provided TypedArray with cryptographically secure random values.
T
The input array filled with cryptographically secure random values.
Example
const byteArray = new Uint8Array(16);
Crypto.getRandomValues(byteArray);
console.log('Your lucky bytes: ' + byteArray);
Crypto.randomUUID()
The randomUUID() method returns a unique identifier based on the V4 UUID spec (RFC4122).
It uses cryptographically secure random values to generate the UUID.
string
A string containing a newly generated UUIDv4 identifier
Example
const UUID = Crypto.randomUUID();
console.log('Your UUID: ' + UUID);
Types
CryptoDigestOptions
| Name | Type | Description |
|---|---|---|
| encoding | CryptoEncoding | Format the digest is returned in. |
Enums
BASE64
CryptoEncoding.BASE64 ＝ "base64"Has trailing padding. Does not wrap lines. Does not have a trailing newline.
HEX
CryptoEncoding.HEX ＝ "hex"Error codes
| Code | Description |
|---|---|
ERR_CRYPTO_UNAVAILABLE | Web Only. Access to the WebCrypto API is restricted to secure origins (localhost/https). |
ERR_CRYPTO_DIGEST | An invalid encoding type provided. |