A universal library for crypto operations.
expo-crypto
enables you to hash data in an equivalent manner to the Node.js core crypto
API.
-
npx expo install expo-crypto
If 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.
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',
},
});
import * as Crypto from 'expo-crypto';
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<T>(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);
CryptoDigestOptions
Name | Type | Description |
---|---|---|
encoding | CryptoEncoding | Format the digest is returned in. |
Digest
Type: string
CryptoEncoding
CryptoEncoding Values
BASE64
CryptoEncoding.BASE64 = "base64"
Has trailing padding. Does not wrap lines. Does not have a trailing newline.
HEX
CryptoEncoding.HEX = "hex"
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. |