JWT vs. OAuth: Which Is Better for Ultimate Web Security?

User authentication and authorization are critical for securing web applications. Two popular technologies for handling these tasks are JSON Web Tokens (JWT) and OAuth. But which one is better for achieving robust security for your web app?

In this comprehensive guide, we‘ll dive deep into JWT vs. OAuth, comparing their strengths and weaknesses. By the end, you‘ll understand:

What JWT and OAuth are
Their main differences
Benefits and drawbacks of each
When to use JWT or OAuth
If you can use JWT and OAuth together

Equipped with this knowledge, you‘ll be able to pick the right approach to lock down user access for your specific application architecture and needs. Let‘s get started!

What is JWT?

JWT, short for JSON Web Token, is an open standard for securely transmitting information between parties in a compact and self-contained way.

Here‘s an example JWT:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

This token is comprised of three parts:

Header – contains metadata like the algorithm used to generate the signature
Payload – holds information about the user and additional data
Signature – is used to verify the message wasn‘t changed along the way

The header and payload are Base64 encoded to produce the first two sections of the JWT. The signature is generated by creating a hash of the header and payload sections, along with a secret.

This enables the receiver to validate the authenticity of the token by recomputing the hash and comparing it to the signature.

How Does JWT Work?

The JSON Web Token workflow looks like this:

User authenticates with login credentials
Authentication server verifies credentials
Server generates a JWT and sends it to the client
Client stores JWT and includes it in requests
Resource server validates JWT signature and claims

When the user wants to access a protected route or resource, the client sends the JWT in the request‘s Authorization header.

The API can then verify that the JWT‘s signature matches the payload and header to ensure it is authentic. Next, it checks the token‘s expiration time, audience, and other claims to authorize access.

If everything checks out, the user is granted access to the resource.

Benefits of Using JWT

There are several advantages to using JSON Web Tokens:

Compact – JWTs are very compact compared to other standards like SAML, making them perfect for use in HTML/HTTP environments.
Self-contained – All the necessary information is in the token itself, reducing the need to query the database multiple times.
Secure – JWTs can be signed using a secret with the HMAC algorithm or a public/private key pair using RSA or ECDSA. This ensures the integrity of the token.
Portable – JWTs are in a standard format, so they can be easily transmitted across different domains and APIs.
Scalable – The stateless nature of JWTs helps easily scale to millions of users.
Expiry – You can set an expiration time after which the token will no longer be valid, reducing the risk of interception.

Overall, the lightweight yet secure nature of JWTs makes them very useful for handling authentication/authorization in modern applications.

Limitations of JWT

However, some downsides to consider with JSON Web Tokens include:

Not easily revocable – There is no built-in mechanism for revoking JWTs before expiration. You would need to maintain a blacklist of revoked tokens on the server side.
Potential for exploitation – If an attacker gets access to the secret used to sign tokens, they could forge valid JWTs and gain unauthorized access.
No built-in authorization – JWTs only confirm identity but don‘t handle detailed access controls. You would need to implement ACLs separately.
Multiple tokens – For more complex applications, you may need to manage multiple JWTs i.e access tokens, refresh tokens, which adds complexity.
Stateful on server – Even though JWTs themselves are stateless, the server still needs to maintain state for aspects like token expiry and blacklisting.
Verbose – JWTs contain more data than simple session IDs, which can add overhead especially for mobile apps.

Overall, the lack of built-in revocation and centralized authorization controls means you need to put in extra work to handle those with JWTs.

What is OAuth 2.0?

OAuth 2.0 is an authorization framework that allows applications to get limited access to user data on an HTTP service, without requiring the user to expose their password. It is used to implement authorization flows for web, desktop and mobile apps.

For example, you can see "Sign in with Google" buttons on many websites. This allows you to login with your Google account credentials, without sharing the password with that website. Behind the scenes, OAuth 2.0 enables this secure authorization flow.

Some key OAuth concepts include:

Resource owner – The entity that can grant access to a protected resource, typically the end-user.
Resource server – The server hosting the protected data i.e. user data, API, etc.
Client – The application requesting access to the resource.
Authorization server – The server that authenticates the client and issues access tokens.

OAuth 2.0 roles and responsibilities are modular, enabling various servers and components to handle each task.

How Does OAuth 2.0 Work?

The OAuth 2.0 authorization flow involves a series of transactions between the client, resource owner, authorization server and resource server.

Here is a simplified example:

User tries to access Client App A, which needs to access data from Resource Server X on the user‘s behalf
Client App A redirects user to Authorization Server and requests an authorization grant
User logs in to Authorization Server and consents to grant access
Authorization Server issues an authorization grant to Client App A
Client App A presents the authorization grant to Authorization Server to get an access token
Client App A requests user data from Resource Server X with access token
Resource Server X sends data to Client App A after validating access token

This allows Client App A to get access to the protected resource without ever handling the user‘s credentials directly. The user only enters their login details with the Authorization Server.

OAuth supports several grant types for different use cases, but the overall flow is similar.

Benefits of Using OAuth 2.0

OAuth 2.0 provides several advantages for authorization:

Standard protocol – OAuth 2.0 is an open standard with wide adoption making integration easier.
Access delegation – Users can authorize third-party apps without sharing passwords.
Incremental authorization – Scoped access control allows granting limited permissions.
Works with TLS – OAuth requires TLS for secure communication.
Loose coupling – Client apps are isolated from resource servers, enabling independent evolution.
Multitude of flows – OAuth‘s flexibility through grant types handles many modern authentication scenarios.

Overall, OAuth 2.0 establishes a secure, standardized authorization layer for your infrastructure and integrations.

Limitations of OAuth 2.0

However, OAuth 2.0 also comes with some downsides:

Complex specification – The OAuth specs are complex with many extensions, which can make it hard to implement fully and securely.
Many moving parts – The modular nature requires handling multiple tokens, endpoint URLs, grant types, scopes, etc.
Requires TLS – OAuth relies on TLS encryption which adds overhead compared to shared secrets.
Access token management – You need a secure way to issue, revoke and store access tokens on the server side.
Stateful – OAuth requires maintaining significant server-side state for security, unlike JWTs.
Provides authorization, not authentication – OAuth isn‘t meant for authentication; you still need a separate identity provider.

Overall, the complexity from OAuth‘s flexibility takes effort to implement and integrate securely.

JWT vs. OAuth Summary

	JWT	OAuth 2.0
Type	An open standard defining format for secure tokens	An authorization framework and protocol
Use case	Mainly used for authentication	Used for authorization
Storage	Stored on client side	Requires both client-side and server-side storage
Security	Leverages signatures and encryption	Relies on TLS and secure token management
Complexity	Fairly simple to implement and understand	More involved with multiple components and transactions
Custom scopes	Scopes and claims can be customized in the JWT payload	Scopes are defined by the resource server for granular access

To summarize:

JWT is the simpler mechanism that handles user authentication through signed, encrypted tokens.
OAuth 2.0 provides an extensive authorization framework for delegated access control.

So in general, JWT is used for authentication whereas OAuth 2.0 is used for authorization.

But they also often work together, which we‘ll examine next.

Using JWT and OAuth 2.0 Together

JWT and OAuth serve different but complementary purposes. JWTs are commonly used within OAuth flows to handle identity and session data.

Here are two ways JWT and OAuth can work together:

1. OAuth Access Token + JWT for Identity

A common approach is to have OAuth issue an opaque access token, which is then passed to the API. The API validates the access token and then looks up the associated JWT by user ID to retrieve identity details.

This provides several benefits:

Keeps OAuth access tokens small yet secure
Enables easy API access to identity claims from the JWT
Allows refreshing OAuth tokens without reissuing new JWTs

2. OAuth for Authorization + Signed JWT as Access Token

In this approach, OAuth‘s authorization server issues a signed JWT as the access token itself. This access token JWT contains all the user identity claims.

Benefits include:

Avoid database lookups – identity is in access token
Fine-grained access control via OAuth scopes
Integrity ensured through JWT signature

The downside is larger OAuth access tokens due to embedded JWT claims.

Either way, the standards work very well together to handle the distinct needs of authentication and authorization required by modern applications.

Conclusion

There is no simple answer to whether JWT or OAuth 2.0 is absolutely "better" for web security. Each has their own strengths and weaknesses.

Here are some guidelines on when to use JWT vs. OAuth:

Use JWT if you just need session-based user authentication for your API.
Use OAuth 2.0 if you need delegation and granular access controls across different services and 3rd parties.
Use OAuth + JWT together if you require both capabilities.

Carefully analyze your identity management, access control and infrastructure requirements. This will dictate whether JWT, OAuth or both together are best suited for your application.

The most robust web security comes from defense-in-depth. Employ a combination of technologies like Multifactor Authentication, Web Application Firewalls, Role-based Access Controls, API Gateways, etc.

Along with JWT and/or OAuth for identity and authorization, this will enable you to lock down user access and secure your web applications from threats.