expo-totp

A library that providers client side TOTP(Time-based One-Time Password) generation.

Made with Expo Modules API.

expo-totp is not available in Expo Go, learn more about development builds.

API documentation

• Documentation for the main branch
• Documentation for the latest stable release

Installation in managed Expo projects

For managed Expo projects, please follow the installation instructions in the API documentation for the latest stable release. If you follow the link and there is no documentation available then this library is not yet usable within managed projects — it is likely to be included in an upcoming Expo SDK release.

Installation in bare React Native projects

For bare React Native projects, you must ensure that you have installed and configured the expo package before continuing.

Add the package to your npm dependencies

npx expo install expo-totp

Demo

Usage

import { useExpoTotp } from "expo-totp";
import { Button, SafeAreaView, StyleSheet, Text } from "react-native";

export default function App() {
  const totp = useExpoTotp();

  const start = () => {
    // Supports only ASCII secret keys
    totp.start("MY_SUPER_SECRET_KEY", {
      algorithm: "SHA512",
      digits: 6,
      interval: 30,
    });
  };

  const stop = () => {
    totp.stop();
  };

  return (
    <SafeAreaView style={styles.container}>
      {!!totp.code && (
        <>
          <Text style={styles.code}>{totp.code}</Text>
          <Text style={styles.text}>Time: {totp.remainingTime} s</Text>
          <Text style={styles.text}>
            Progress: {totp.progress?.toFixed(1)}%
          </Text>
        </>
      )}
      <Button title="Start" onPress={start} />
      <Button title="Stop" onPress={stop} />
    </SafeAreaView>
  );
}

const styles = StyleSheet.create({
  text: {
    fontSize: 16,
    alignSelf: "center",
  },
  code: {
    fontSize: 24,
    fontWeight: "bold",
    letterSpacing: 8,
    alignSelf: "center",
  },
  container: {
    flex: 1,
    paddingHorizontal: 32,
    gap: 16,
    backgroundColor: "#eee",
    justifyContent: "center",
    alignContent: "center",
  },
});

API

import ExpoTotp, { useExpoTotp } from "expo-totp";

Hooks

useExpoTotp()

Easy to use hook for obtain otp info, start and stop.

const { code, progress, remainingTime, start, stop } = useExpoTotp();

Methods

getTotp()

Compute TOTP once

const totp = await ExpoTotp.getTotp("MY_SUPER_SECRET_KEY",
  interval: 30,
  digits: 6,
  algorithm: "SHA512"
)

startUpdates()

Start TOTP generation

ExpoTotp.startUpdates("YOUR_SUPER_SECRET_KEY", {
  interval: 30,
  digits: 6,
  algorithm: "SHA512",
});

addListener()

Listen for updates with ExpoTotp.addListener()

useEffect(() => {
  const listener = ExpoTotp.addListener("onTotpUpdate", (totp: TotpPayload) => {
    // your logic goes here...
  });
  return () => listener.remove();
}, []);

or

import { useEvent } from "expo";
const totp = useEvent(ExpoTotp, "onTotpUpdate");

stopUpdates()

Stop any TOTP generation

ExpoTotp.stopUpdates();

Interfaces

TotpOptions

Defines options for TOTP generation

type TotpOptions = {
  interval: number;
  digits: number;
  algorithm: HmacAlgorithm;
};

HmacAlgorithm

Defines options for TOTP generation

type HmacAlgorithm = "SHA512" | "SHA384" | "SHA256" | "SHA1" | "MD5";

Property	Type	Default	Description
interval	number	30	Interval in seconds
digits	number	6	Amount of digits
algorithm	HmacAlgorithm	SHA512	Algorithm to be used.

TotpPayload

Defines the payload for onTotpUpdate event listener

export type TotpPayload = {
  code: string;
  remainingTime: number;
  progress: number;
};

Contributing

Contributions are very welcome! Please refer to guidelines described in the contributing guide.