Machine-to-Machine Authentication: JWTs vs API Keys

Machine-to-machine (M2M) authentication is crucial for ensuring secure communication between devices. This guide explores how Userfront handles M2M authentication, providing an in-depth look at the options available, including JSON Web Tokens (JWTs) and API keys, and how they can be tailored to meet specific security requirements.

What is Machine-to-Machine Authentication?

Machine-to-machine (M2M) authentication refers to the process by which devices in a network authenticate each other to establish trust and securely exchange information. Unlike traditional user-to-machine authentication, M2M authentication operates without human intervention, making it essential for automated processes, such as those found in IoT networks, microservices architectures, and large-scale API integrations.

M2M authentication can be implemented using various methods, with the most common being JSON Web Tokens (JWTs) and API keys. Each method offers distinct advantages depending on the specific use case, security requirements, and the complexity of the network. JWTs, for example, provide a scalable and secure solution for APIs that serve multiple clients, while API keys offer a simpler approach for scenarios with basic security needs.

Understanding the nuances of these authentication methods is crucial for selecting the right solution for your system, ensuring that your devices can communicate securely and efficiently in even the most complex environments.

How Userfront Handles M2M Authentication

Userfront has a flexible approach that allows machine-to-machine authentication via:

•  JSON Web Tokens (JWTs); or
•  API keys

The best option for your specific use case will depend on several factors, including your security requirements, API architecture, and levels of authorization.

If your API only needs to grant basic read access to non-sensitive information and doesn’t require granular permissions and access control, API keys can be easier to implement than JWTs.

However, if your API serves multiple clients, such as an external-facing API or in a microservices architecture,  JWTs are a more secure and scalable alternative to API keys. JWTs are signed, self-contained tokens that can provide granular levels of permissions for each tenant without the need for multiple API calls.

Machine-to-Machine Auth with JWTs

1. JWT Access Token Generation

Your application or device makes an authentication request to Userfront using any of the authentication methods you choose. 

Userfront receives the request, generates a JWT access token with your desired payload and expiration, and returns the JWT access token to the requesting device. 

In addition to standard claims, the JWT access token can also contain custom claims in its payload.

The JWT access token can also be scoped to any parent or nested tenant within your application, ensuring that access is granted at the appropriate level(s) for the requesting device.

2. JWT Access Token Distribution

Userfront returns the JWT access token to the requesting device. The device then uses this token for subsequent authenticated requests to other devices in your system.

3. JWT Access Token Usage

When a device wants to communicate with another device or a server in your system, it includes the JWT in the HTTP header. The receiving device verifies the JWT access token by checking the token's signature using a public key to ensure it was generated securely. 

The receiving device then validates the JWT claims (e.g., ensuring the token is not expired and is intended for the correct audience) as well as any authorization levels contained within the JWT payload.

Machine-to-Machine Auth with API Keys

1. API Key Retrieval

Your application or device makes an authentication request to Userfront using any of the authentication methods you choose. Userfront receives the request and returns an API key to the requesting device. 

The API key can be scoped to any parent or nested tenant within your application, ensuring that access is granted at the appropriate level(s) for the requesting device.

2. API Key Distribution

Userfront returns the API key to the requesting device. The device then uses this API key for subsequent authenticated requests to other devices in your system.

3. API Key Usage

When a device wants to communicate with another device or a server in your system, it includes the API key in the HTTP header. The receiving device can either already contain the API key and check for a match, or it can send the API key to Userfront for verification.

4. API Key Verification Request (optional)

If the receiving device does not have the API key stored, it can make a request to Userfront’s verify API key endpoint with the API key in the HTTP header.

5. API Key Verification Response (optional)

Userfront returns a response indicating whether the API key is valid, and if so, for which tenant.

Why it Works

Machine-to-machine authentication via JWT access tokens or API keys allow multiple machines in a network to establish trust and communicate securely.

Userfront further allows fine-grained machine-to-machine authorization by combining its flexible, nestable access control layer with automated machine interactions. This allows each machine to request only the level of access that it needs.

Userfront’s tenant model unlocks fine-grained M2M auth that molds to any use case. JWT access tokens and API keys can be scoped globally or to any level of tenant or sub-tenant. This means that access can be scoped to any of the following:

• Application-wide
• Organization (tenant) within the application
• Sub-organizations (child tenants) within an organization
• An individual user or machine record

Auditing and Compliance

Userfront can record every instance of access requested for machine-to-machine interactions, as well as invalid, expired, and out-of-scope attempts to validate a machine and can provide security and compliance reporting for audits and security reviews.

In addition to detailed logging and reporting, Userfront adheres to industry standards and regulatory requirements, such as GDPR and SOC 2, providing peace of mind that your data management practices are compliant with global regulations.

By leveraging these compliance tools, Userfront helps organizations maintain a robust security posture and ensures adherence to best practices in data protection and privacy.

Migrating Machine-to-Machine Auth

If needed, Userfront can migrate most machine-to-machine auth systems in a backwards-compatible manner. The specifics for this will depend on your system, but most JWT-based approaches and many API key-based approaches can be migrated seamlessly.

The integration of Userfront’s machine-to-machine authentication framework into Hapbee’s systems would improve the flexibility of Hapbee’s M2M protocols while increasing developer satisfaction.