Authentication is one of the core components of application security. It seeks to ascertain the identity of users and systems involved in the application. In contemporary web and mobilization tendencies, authentication is carried out mainly through tokens and keys. Let us probe into advanced mechanisms used in the most common of them all:
OAuth: A protocol for token sharing among different services to access granted permissions.
JWT: A signed token with a preset structure used for information exchange.
API Keys: A means of identifying and authenticating users attempting to access the API.
All these approaches are each good at a particular usage but poorly implemented in others.
What is OAuth?
OAuth (Open Authorization) is a standard that enables application users to grant access to their data from another site (e.g. Google, Facebook, GitHub) to third parties without sharing their credentials. OAuth is often used for social network sign ins or for integrating applications with other services.
Oauth Flow
OAuth is implemented in the form of a sequence of token exchanges.
Customer Asks For Permission: The app asks the user if it could access her resources.
User consent: The user who wants to allow access does so via the provider’s login page.
Authorization code is sent: Next this user is asked to approve what the client wishes. In response to approval, an authorization server assigns to the client an authorization code.
Code is sent to authorize the client: The client uses the authorization code with the OAuth server to get an access token.
Resources are requested using access token: The application gets the user’s resources with the given token.
When Not To Use OAuth
Third-party login: In case you need users to sign in to your app via Google, Facebook, etc.
Delegated access: All of the above, but your app has to integrate as well with for example Google Drive or Twitter on the user’s behalf.
Advantages and Disadvantages of OAuth
Advantages:
No need to exchange passwords: Users are not obliged to exchange their passwords with third-party applications.
Delegated Access and Related Risks: This allows exposing only a part of the user’s information when such a case occurs, thus lowering the threat of overexposing the user.
Vast support base: OAuth is supported by most of the known service providers such as Google, Facebook, Twitter and GitHub.
Disadvantages:
Inherent nature of implementation: Due to multiple token exchanges and the need for refresh tokens, implementation of OAuth is not that straightforward.
Maximum length of scaling: Restriction to the extent articulated beforehand could be a limitation
Shortcomings: Security risks are present due to possible incorrect deployment. For example, OAuth token leaks.
What is JWT?
JWT (JSON Web Token) is a token format that is widely used to securely send messages between two parties. An authentication method based on JWTs is called stateless, where the server doesn’t store any session.
How JWT Works
User authentication: In this part the user enters his credentials (for example, username/password).
In case the user is authenticated, a JWT is created by the server, this JWT will contain some claims (which are basically the user data) and it will be signed with a secret key.
Client stores JWT: The client keeps that token and stores it usually in local storage or cookies.
Access resources using JWT: The client communicates its request along with the JWT it carries. The JWT is mostly carried in the the Authorization header.
Server keeps JWT: The server checks to see if the token is present. If so it processes the request.
A JWT is made of three parts:
Header: Describes the algorithm and type of the token.
Payload: Consist of claims (information about the user).
Signature: Confirms whether the token was edited or not.
When to Use JWT
Stateless authentication: If you do not wish to keep the session data on the server side.
Single sign on (SSO): Actively supports sso implementations.
API security: When including API(s) for web or mobile applications, JWTs are given with every request to confirm the user.
The advantages and disadvantages of the JWT
Advantages:
No Statefulness: Server-side either backend or session data does not have to be stored which leads to better scalability.
Diminutive: A much smaller size enables effective use of JWTS for transmission through HTTP headers.
Well-protected: Security is also taken a step further because the tokens can be encrypted as well as signed.
Disadvantages:
No token revocation: Without measures like server-side blacklisting, confused JWT owners cannot get their tokens back.
Payload size: There is a downside such that placing more payload information increases the token size.
Short-lived tokens: Expiration should always be handled to cover risks abuse.
What are API Keys?
An API Key is a simple string (token) passed along with API requests to identify the client and grant access to the API. API Keys are often used in backend services or server-to-server communication.
How API Keys Work
API key is issued: When an API consumer registers for access, the server issues an API key.
API key is passed with requests: The client app sends the key with every request, usually in the header or query string.
Server validates API key: The server checks the key and processes the request if valid.
When to Use API Keys
Public APIs: When there is a need for access control but there is no need to specify the end user (e.g. on Google Maps API).
Rate limiting: When you want to monitor or constrain API access by known applications.
Basic access control: It works best for less secured APIs where the entire OAuth or JWT cannot be implemented.
Pros and Cons of API Keys
Advantages:
Easiness: Straightforward to generate and implement for the client as well as the server.
Monitor consumption: Enables well-documented record keeping of the consumption of the API with respect to each client/application.
No user session needed: Practical for server-to-server connections that do not require access to or verification of a user.
Disadvantages:
Weak security: API keys can be easily intercepted if not used with HTTPS, leading to unauthorized access.
No user identity: API keys only authenticate the application, not the user.
Hard to revoke: API keys are static, so if compromised, all requests using the key are at risk.
Comparing OAuth, JWT, and API Keys
| Feature | OAuth | JWT | API Key |
|---|---|---|---|
| Use Case | Third-party login, delegated access | Stateless authentication, secure APIs | Public APIs, basic API authentication |
| User Authentication | Yes | Yes | No |
| Access Control | Fine-grained control with scopes | Control via token claims | Simple access control |
| Security | High (with proper implementation) | High (if token signing is done securely) | Moderate (depends on transmission) |
| Implementation | Complex | Medium | Simple |
| Token Revocation | Possible with refresh tokens | Harder (requires blacklist) | Difficult (requires key regeneration) |
| Best For | OAuth-based logins (Google, Facebook) | Mobile apps, SPAs, APIs | Public APIs, server-to-server requests |