Handling token rotation and key updates with JWTs

03 Oct 2023

tags
JWTs

Introduction

JSON Web Tokens (JWTs) have become a popular method for representing claims between two parties. They are commonly used for authentication and authorization purposes in web applications. JWTs consist of three parts: a header, payload, and signature. The signature is used to verify the integrity of the token and ensure it has not been tampered with.

One challenge when using JWTs is handling token rotation and key updates. JWTs have an expiration time, after which they are considered invalid. When a token needs to be renewed or rotated, it’s important to ensure a smooth transition without disrupting the user experience. In addition, periodically updating the signing key helps enhance security and mitigate the impact of a compromised key.

In this blog post, we will discuss some best practices for handling token rotation and key updates with JWTs.

Token Rotation

Token rotation involves renewing or replacing an existing token with a new one. This is usually done to prevent long-lived tokens from being misused if they are compromised. To implement token rotation effectively, consider the following steps:

Token Refresh Endpoint: Implement a token refresh endpoint on your authentication server. This endpoint should accept a valid JWT and return a new JWT with an extended expiration time.
```
POST /refresh-token
Authorization: Bearer <old_token>
```
The server should verify the validity of the old token, generate a new token, and return it as a response.
Client-Side Handling: On the client-side, intercept the expiration of the token and initiate a token refresh request. This can be done by setting up a timer or checking the token expiration during each API request. When the token is about to expire, send a request to the token refresh endpoint to obtain a new token.
```
if (tokenExpiresSoon()) {
    refreshToken();
}
```
The new token can then be used for subsequent authenticated API requests.

Key Updates

Updating signing keys helps protect against compromised keys and enhances the overall security of your JWT implementation. To handle key updates smoothly, follow these best practices:

Key Rotation Policy: Establish a key rotation policy that defines the frequency and process of key updates. This policy should specify how often keys should be rotated and the steps involved.
Key Versioning: Assign a version number to each signing key. This allows you to keep track of which keys are currently active and which ones are obsolete. When verifying a JWT, check the key version specified in the header and use the corresponding key for signature verification.
Rollout Plan: Plan the rollout of new keys carefully to avoid disruption. Generate new keys well in advance and give yourself enough time to update all relevant components, such as authentication servers and API gateways. Gradually switch the JWT verification process to use the new key while still accepting tokens signed with the older key.

Conclusion

Handling token rotation and key updates effectively is crucial for maintaining the security and integrity of your JWT-based authentication system. By implementing token rotation and following key update best practices, you can ensure a smooth transition without disrupting your users’ experience while keeping your system secure.

Remember to regularly review and update your token rotation and key update mechanisms to stay ahead of potential security threats.

#tags: #JWTs #TokenRotation