JSON Web Tokens (JWT) are an effective way to manage authentication and authorization in Node.js applications. JWTs are encrypted tokens that contain information about the user that can be verified to ensure requests are coming from a trusted source. In this chapter, we are going to discuss how to handle refresh tokens in NodeJS.
Refresh tokens play a crucial role in maintaining user security and reducing the need for the user to log in repeatedly. A refresh token is a special type of token used to get a new access token. It has a longer lifetime than the access token, allowing users to remain authenticated without having to re-enter their credentials.
To start working with JWT and refresh tokens, we first need to install the jsonwebtoken library. In the terminal, run the following command:
npm install jsonwebtoken
Once the library is installed, you can create tokens using the sign() method. This method accepts three arguments: the payload, the secret key, and the options. The payload contains the user's information, the secret key is used to sign and verify the token, and options can include things like the signature algorithm and token validity.
const jwt = require('jsonwebtoken');
const payload = { userId: user.id };
const secret = 'your-secret-key';
const options = { expiresIn: '1h' };
const token = jwt.sign(payload, secret, options);
Now that we have our token, we can send this to the client so they can use it in subsequent requests. When the client sends a request with a token, we can use the verify() method to ensure that the token is valid.
const token = req.headers.authorization;
try {
const decoded = jwt.verify(token, 'your-secret-key');
req.user = decoded;
} catch(err) {
res.status(401).send('Invalid token');
}
So how do refresh tokens fit into this? Well, when the access token expires, the user would need to login again to get a new one. To avoid this, we can issue a refresh token along with the access token. The refresh token has a much longer validity and can be used to get a new access token without requiring the user to log in again.
To issue a refresh token, we can use the same sign() method, but with a longer expiration time.
const refreshToken = jwt.sign(payload, 'your-refresh-token-secret', { expiresIn: '7d' });
When the access token expires, the client can send a request with the refresh token to get a new access token. We can then check the refresh token the same way we did the access token. If the refresh token is valid, we issue a new access token.
const refreshToken = req.body.token;
try {
const decoded = jwt.verify(refreshToken, 'your-refresh-token-secret');
const newAccessToken = jwt.sign({ userId: decoded.userId }, 'your-secret-key', { expiresIn: '1h' });
res.json({ accessToken: newAccessToken });
} catch(err) {
res.status(401).send('Invalid refresh token');
}
It is important to note that refresh tokens can also expire. When this happens, the user will need to log in again. Additionally, you should treat refresh tokens like passwords and store them securely.
In summary, refresh tokens are an essential part of managing authentication and authorization in Node.js applications. They allow users to remain authenticated for longer periods of time without having to repeatedly enter their credentials. At the same time, they help maintain application security by ensuring that only requests from trusted sources are accepted.
