Overview of API authentication methods

Security is a key concept in everything these days, including APIs; therefore, securing API access is one of the main challenges in the digital landscape. In this blog, we will go through some of the most common API authentication methods, from Basic Authentication to more complex ones such as OAuth, SAML and TLS authentication. We will understand the difference between authentication, which is verification of identity, and authorization, which is granting access based on identity. So, whether you’re a developer or a tech enthusiast, this blog gives you a comprehensive understanding of these concepts and helps you select the best authentication method for your applications.

Difference between authentication and authorization

Before we go into the most common API authentication methods, we must understand the differences between authentication and authorization.

Authentication verifies your identity. Let’s say you’re going to travel to another country; at the airport, they need to confirm your identity, so you must show your passport. In this example, authentication is the process of confirming your identification to the officer using your passport. On the Internet, authentication happens when you log in with a username and password or use Single Sign-On (SSO) or other authentication methods.

Authorization defines your access rights. Continuing with the airport example, you get to your departure gate after a passport check and verifying your identity. Your boarding pass is now checked before you are authorized to board the plane. This process is similar to authorization; once authorized, you’re granted permission to access specific resources or perform specific actions within a system or application.

Basic Auth

Basic Authentication is a simple but effective approach to securing web services. It works in a simple way; it requires users to authenticate requests with their username and password. This method is widely used in online services and applications because of its simple implementation and ease of use.

How Basic Authentication Works

Let’s see how basic authentication works. It concatenates the username and password provided by the user and encodes it in base64, then sends it in the HTTP Authorization header as Authorization: Basic <encoded_credentials>. These actions are defined within the HTTP protocol to ensure native support across web browsers and HTTP clients, which allows for a smooth integration into web apps.

For instance, imagine we have an API that supports Basic Auth; our username is “teddy”, and the password is “bear”.

• First, we should get the Base64 version of teddy:bear (following the username

  format). The Base64 of teddy:bear would be dGVkZHk6YmVhcg==

• We should add the Authorization: Basic dGVkZHk6YmVhcg== header to the request.

The header field might look like the following:

Authorization: Basic dGVkZHk6YmVhcg==

Implementing Basic Authentication

To implement Basic Authentication, follow these steps:

• Configure Your Web Server: Set your web server to prompt clients for authentication when they visit protected resources.
• Credential Prompting: Use the default credential prompting mechanism web browsers offer or implement custom login forms for API access.
• Credential Verification: Use server-side logic to verify the provided credentials against a secure user database.

Security Considerations for Basic Authentication

Basic Authentication is simple, but user credentials are at risk because they can be captured, especially if the credentials are not being protected by TLS, which can lead to a severe security risk.

Advantages and Limitations

Advantages

• Simplicity: Its simplicity makes it ideal for internal or low-risk applications.
• Ease of Use: Basic authentication is simple to build and use, requiring little setup.

Limitations

• Security Risks: Without HTTPS, credentials are vulnerable to interception.
• Statelessness: There is no built-in mechanism for token expiration or revocation; therefore, credentials must be sent with each request.

Comparison with Other Authentication Methods

Basic Authentication is popular because of its simplicity and direct approach compared to other authentication methods. However, it needs the advanced security features or even flexibility that other methods provide. If you need higher security, we recommend you use more advanced methods.

Bearer Authentication

Bearer Authenctican is an authentication method that is widely used in RESTful APIs. In the Bearer Authentication method, the client includes a token in the auth header or query parameter and authenticates requests. This method relies on secure token standards, such as JSON Web Token (JWT), to issue access tokens that grant access to protected resources.

How Bearer Authentication Works

The authentication process starts with getting a bearer token from an authentication server. Then, this token is included in HTTP requests through the Authorization: Bearer <token> header, which tells the server that the client is authenticated and authorized to access the specified resources.

For example:

Authorization: Bearer eyJhbGciOnR5cCI6IkpXVCJ9

Implementing Bearer Authentication

To set up Bearer Authentication for APIs, follow these steps:

1. Token Generation: Implement a secure method for generating and issuing tokens.
2. Endpoint Protection: Make sure your API endpoints are configured to require a valid bearer token for access.
3. Token Validation: On the server, validate incoming tokens to ensure their authenticity and integrity.
4. HTTPS Enforcement: Use HTTPS to encrypt communications and prevent token interception in transit.

Security Considerations for Bearer Tokens

Adhering to security best practices is critical for safeguarding bearer tokens:

• Token Expiration: Use token expiration to limit the duration of access.
• Secure Storage: To prevent unauthorized access, ensure that tokens are safely kept on the client side.
• HTTPS Use: The mandatory usage of HTTPS protects tokens in transit from being intercepted by malicious parties.
• Avoiding Threats: Use robust token validation procedures and secure handling practices to avoid typical security threats like token leakage and replay attacks.

Advantages and Limitations

Advantages

• Statelessness: Bearer tokens do not require server-side session storage, which improves scalability.
• Distributed Systems: Distributed systems are ideal for authentication because they are self-contained.

Limitations

• Security Risks: If a bearer token is intercepted or leaked, an attacker may get access to protected resources without additional verification.

API Keys

API keys are a simple but effective approach for controlling access to web APIs. They are a unique identifier for each request the client sends, allowing for more accurate tracking and control over how an API is used. API keys are commonly used to monitor API usage and limit access to avoid misuse. For a more in-depth review of API keys, how to acquire one, secure, and use them, please read the What is API key article.

How API Keys Work

The API Key authentication method generates a unique key linked with a user or client and then inserts it into server requests by attaching the key to query parameters, embedding it in request headers, or including it in the request body, guaranteeing each request is authenticated.

Implementing API Key Authentication

To implement API key authentication effectively:

1. Key Generation and Distribution: Generate unique API keys for users and developers, ensuring each key is suitably random and secure.
2. Server-Side Validation: Upon receiving a request, compare the API Key to stored records to authenticate the user or client.
3. Secure Storage and Management: Store API keys securely, preventing unauthorized access and ensuring secure management.
4. Rate Limiting and Monitoring: To prevent abuse and guarantee optimal service performance, limit API usage and monitor it continuously.

Security Considerations for API Keys

While API keys are a great tool for API security, there are special security considerations:

• Confidentiality: API keys should be treated as confidential information, kept secret, and not shared in public repositories or client-side code.
• Secure Transmission: Use HTTPS to ensure that API keys are safely transmitted over the internet, protecting them from interception.
• Key Rotation: Rotate API Keys regularly to reduce the chance of compromise and encourage users to update their keys as needed.

Advantages and Limitations

Advantages

• Simplicity: API keys are simple to construct and use, making them accessible to both API providers and consumers.
• Flexibility: They offer a basic level of security that may be quickly integrated into various systems without requiring substantial configuration.

Limitations

• Security Depth: API keys alone do not provide comprehensive authentication or authorization, especially for sensitive or private data. They work best in combination with more complex security methods.
• Depth of Control: API Keys do not support specific permissions or roles.

JWT Authentication Method

JSON Web Tokens (JWT) is a compact and URL-safe authentication method representing claims that will be exchanged between two parties. JWT is a useful way to share information and authenticate because it’s stateless and has smooth integration. It’s a good choice for developers who want to secure client-server communications and manage user sessions quickly.

How JWT Authentication Works

A JWT is divided into three separate parts:

• Header: Indicates the type of token (JWT) and the signing algorithm (e.g., HMAC, RSA) that is being used.

  Example header:

  {
    "alg": "HS256",
    "typ": "JWT"
  }

• Payload: Contains the claims, which are statements about an entity (typically, the user) and additional metadata. There are three types of claims: registered, public, and private claims.

  Sample payload:

  {
    "sub": "1234567890",
    "name": "Rick Sanchez",
    "admin": true
  }

• Signature: A cryptographic signature that secures the token and verifies its integrity.

Generating and verifying JWTs depends on cryptographic algorithms. While RSA or ECDSA algorithms use a public/private key pair to improve security through asymmetric cryptography, HMAC algorithms use a secret key for both signing and verification.

Implementing JWT Authentication

The implementation of JWT Authentication within an application follows these steps:

1. Token Generation: Upon successful user authentication, the server generates a JWT with a defined set of claims and sends it back to the client.
2. Token Usage: The client includes this token in the HTTP header of subsequent requests, offering a method to maintain the session state.
3. Token Verification: The server verifies the token’s signature at each request before granting access to protected resources, ensuring the request’s authenticity.

Managing token expiration and implementing refresh mechanisms are critical for maintaining security while ensuring a smooth user experience.

Benefits and Challenges of JWT Authentication

Benefits

• Scalability: Because JWT is stateless, it is easy to scale and manage sessions.
• Cross-Domain Requests: Its compact structure allows for simple cross-domain requests.
• Security: JWTs offer mechanisms for verifying the token’s integrity and authenticity.

Challenges

• Token Storage & Security: JWTs must be securely stored to avoid unauthorised access.
• Secure Transmission: To avoid interception, tokens should always be transmitted using secure channels.
• Token Expiration and Revocation: Managing token lifecycle and revocation strategies requires careful planning.

Best Practices for JWT Authentication

To secure JWT authentication effectively:

• Use HTTPS: To prevent interception, always transmit tokens using HTTPS.
• Minimize Payload: Keep the token’s payload to a minimum to limit the token’s size and the risk of sensitive information leaking.
• Manage Token Lifecycle: To balance security and user experience, carefully implement token expiration and refresh tokens.
• Secure Key Management: Keep secret or private keys safe to prevent unauthorized token generation or manipulation.

Comparison with Other Authentication Methods

JWT Authentication is popular because of its flexibility and ease of use in different scenarios, especially in single-page applications (SPAs) and microservices. It compliments protocols such as OAuth 2.0 by acting as the token format in various OAuth 2.0 implementations, including OpenID Connect.

JWT has significant advantages in terms of scalability and cross-platform support, but its suitability should be evaluated based on specific security requirements and context of use. In situations that require more complex user authentication and authorization than token validation, it’s better to combine JWT with another authentication framework, such as OAuth 2.0, to have a more secure solution.

OAuth2 Authentication

OAuth 2.0 is an important part of web security that provides an authorization standard that is different from traditional authentication methods. Unlike Basic Auth, which requires sending usernames and passwords with each request, and Bearer Tokens and JWTs (JSON Web Tokens), which allow stateless authentication, OAuth 2.0 takes a more comprehensive approach. It specializes in authorizing third-party access to server resources without exposing user credentials, which improves security in API ecosystems.

How OAuth2 Works

OAuth 2.0 allows a multi-actor authorization process that includes the Resource Owner (usually the user), the Client (the application requesting access), the Authorization Server (validates the user and issues tokens), and the Resource Server (which hosts the protected resources). This model defines responsibilities, resulting in a secure authorization method.

OAuth 2.0 includes four main grant types to cater to various authorization scenarios:

1. Authorization Code: Ideal for clients that can securely store credentials. This is perfect for developing web applications. For example, a user logs into a site, and the site receives a code to access the user’s social media photos.
2. Implicit: Designed for clients unable to store credentials securely, such as in-browser applications. Suitable for mobile apps or web applications where the access token is obtained directly from the authorization server.
3. Client Credentials: Used for server-to-server communication in which no user intervention is required. For instance, a cloud service accesses another cloud API for data syncing.
4. Refresh Token: It allows the application to create a new access token without the user re-authenticating. This method is standard in mobile apps where users should be able to log in without frequently logging in.

Implementing OAuth2

Integrating OAuth 2.0 into your API requires several key steps:

• Application Registration: After registering your application with the Authorization Server, you will receive a Client ID and Client Secret.
• User Consent and Authorization Code: Direct users to an Authorization Server login page to grant access to your application in exchange for an authorization code.
• Authorization Code Exchange: Exchange the received code for an access token at the Authorization Server.
• Access Token Usage: Use the access token to authenticate requests to the Resource Server.

OAuth2 Best Practices

To maintain the security of your OAuth 2.0 implementation, use the following practices:

Enforce HTTPS to secure data in transit. Secure Token Storage: Keep tokens safe to avoid unauthorized access. Manage Token Lifecycle: Handle expiration and refresh tokens effectively to maintain secure access.

Be aware of frequent problems, such as token leakage or inappropriate storage, and take steps to limit these risks.

Comparison with Other Authentication Methods

Compared to other authentication methods, OAuth 2.0 provides a more secure and flexible solution for authorizing third-party resource access. Other methods might offer simple and direct authentication, but the OAuth 2.0 framework is perfect for scenarios that require detailed permission levels and third-party access without exposing user credentials.

OAuth2 Password Grant

The OAuth 2.0 Password Grant is a grant type that allows users to exchange their username and password for an access token directly. This grant type is best suited for scenarios involving trusted applications where users feel comfortable sharing their credentials. Given its nature, it is mostly used in contexts where the application’s safety is guaranteed, and there’s a direct relationship between the user and the application itself.

How OAuth 2.0 Password Grant Works

The flow of the OAuth 2.0 Password Grant is as follows:

• Credential Submission: The user directly provides their username and password to the client application, which sends these credentials to the authorization server.
• Access Token Issuance: After successful authentication, the authorization server sends an access token (and, optionally, a refresh token) to the client application.

This technique emphasizes the importance of secure connections (HTTPS) in protecting the user’s credentials during transmission and preventing possible interceptions.

Steps to Implement OAuth 2.0 Password Grant

Implementing the Password Grant type requires a series of steps:

• Credential Request: The client application prompts the user for their username and password.
• Credential Transmission: The client sends the collected credentials to the authorization server, together with its identification (client ID and secret).

Token Reception: After verifying the credentials, the authorization server returns an access token (and, optionally, a refresh token) to the client. It is vital that user credentials and tokens are handled and stored securely throughout this process.

Security Considerations

Because the Password Grant type handles user credentials directly, it raises severe security concerns. To minimize the associated risks:

Limit Use: Only use this grant type with highly trusted clients when alternative, more secure grant types are not feasible. Encrypt Data: Use robust encryption technologies for data transmission and storage to secure sensitive information.

Advantages and Limitations

Advantages

• Simplicity: Provides an easy way for users to grant access in trusted environments.
• Direct Control: Users have direct control over the authentication process in specific applications.

Disadvantages

• Security Concerns: Direct handling of credentials carries inherent security risks.
• Decreased Favorability: The Password Grant’s popularity is declining as more secure alternatives, such as the Authorization Code Grant with PKCE, gain popularity.

Comparison with Other OAuth 2.0 Grant Types

Compared to other OAuth 2.0 grant types, such as Authorization Code, Client Credentials, Implicit, and Refresh Token, the Password Grant type stands out for its direct and straightforward approach. However, its suitability depends on the application’s context and security requirements, with a general recommendation to choose more secure grant types when possible.

In summary, while the OAuth 2.0 Password Grant type provides a simplified solution for trusted applications, its use should be carefully considered against modern best practices and evolving security standards, with more secure mechanisms preferred wherever applicable.

OAuth1 Authentication

Another authentication method is OAuth 1.0, which is a protocol for securing API authorization in web apps. OAuth 1.0 has a detailed client-server authentication method that relies on signing requests.

Key Components of OAuth 1.0

The OAuth 1.0 architecture is built upon several foundational elements:

• Consumer (Client Application): An application that requests access to the user’s data.
• Service Provider (API): The platform that houses the protected resources.
• User (Resource Owner): The individual who provides the application access to their data.
• OAuth Tokens: This includes both the request token (used to gain user authorization) and the access token (used to access protected resources).

OAuth 1.0 uses signatures as a main security feature; it requires each request to be signed with the consumer’s secret key, therefore increasing the protocol’s security.

OAuth 1.0 Authentication Flow

The OAuth 1.0 authentication process involves a series of steps:

• Obtaining a Request Token: The consumer starts the process by receiving a request token from the service provider.
• User Authorization: The consumer redirects the user to the service provider, who authorizes the request token.
• Exchanging for an Access Token: With the user’s authorization, the consumer exchanges the request token for an access token.

Each phase requires signing requests and verifying signatures, ensuring secure communication throughout the authentication process.

Implementing OAuth 1.0 in Your API

For developers interested in implementing OAuth 1.0, several considerations are essential:

• Signature Generation: Understanding how to create signatures is critical for maintaining the security of requests.
• Token Management: To ensure the authentication process’s integrity, tokens must be securely stored and managed.
• Replay Attack Prevention: Using unique values and timestamps is critical to preventing replay attacks.

OAuth 1.0 Best Practices

To strengthen OAuth 1.0 implementations, follow the security best practices:

• Secure Connections: Use HTTPS to ensure data is securely transmitted for all OAuth transmissions.
• Secret Management: Carefully handle the consumer and token secrets to avoid unauthorized access.

Although OAuth 2.0 has been introduced, and other authentication protocols are more popular, OAuth 1.0 is still handy in some scenarios, and it’s notable for its strict way of securing APIs.

OpenID Authentication

OpenID is a layer of authentication that is built on top of OAuth. It focuses on user authentication and single-sign-on (SSO) on many platforms. While OAuth creates the groundwork for authorization by allowing applications to request access to user data without a password, OpenID extends this framework and verifies user identity specifically. This difference separates OpenID from OAuth 2.0 and OAuth 1.0 because it puts user identity authentication above application access authorization.

How OpenID Works

OpenID uses an organized approach involving three key entities:

1. The End User.
2. The Relying Party (the client application that requires authentication).
3. The Identity Provider (the service that verifies the user’s identity).

Here’s a simple breakdown:

• User Interaction: The End User makes a login attempt with the Relying Party.
• Identity Provider Selection: The user selects or is redirected to their Identity Provider to verify their identity.
• Authentication: The user authenticates with the Identity Provider, often using a username and password, but alternative methods may also be used.
• Token Exchange: After successful authentication, the Identity Provider issues tokens to the Relying Party, which verify the user’s identity without requiring password credentials.

OpenID Connect (OIDC)

The latest edition of OpenID, OpenID Connect, is built on the OAuth 2.0 framework, providing a standardized and simplified approach to identity verification. It introduces a few key concepts:

• ID Tokens: ID Tokens are digital tokens that provide the Relying Party with the End User’s authenticated identity.
• UserInfo Endpoint: An API the Identity Provider provides that the Relying Party can query to obtain additional user information.
• JWTs in OIDC: OpenID Connect uses JSON Web Tokens (JWTs) for ID Tokens, which allows for the safe exchange of information about the authenticated session.

Implementing OpenID Authentication

To add OpenID authentication to your application:

1. Select an OpenID Provider: Choose from popular options like Google and Facebook.
2. Configure YourApplication: Set up your client application to use OpenID Connect and register it with your preferred Identity Provider.
3. Handle Authentication Responses: Process responses from the Identity Provider, verifying the user’s identity using the information in ID tokens.

Benefits and Best Practices

OpenID authentication provides various benefits, including improved user experience through SSO and increased security by removing the need for applications to manage passwords directly. Best practices include:

• Secure Communication: Always use HTTPS to protect data in transit.
• ID Token Validation: Verify the integrity and authenticity of the ID tokens received.
• Privacy and Consent: Follow privacy rules and seek user consent where necessary.

Comparison with Other Authentication Methods

OpenID (especially via OpenID Connect) is better suited to scenarios requiring strict identity verification and SSO functionality than other authentication methods. OpenID is a good choice for applications that require access to user data and want smooth authentication of user identification across services.

SAML Authentication

Security Assertion Markup Language, commonly called SAML, is an XML-based framework that allows authentication and authorization transactions between service providers and identity providers. SAML is a good choice when you want to have seamless access to various services because it enables single sign-on (SSO) across multiple domains. It’s popular because of its robust, secure and efficient way of managing identities across different systems.

Key Components of SAML

A SAML transaction consists of three primary entities:

• Principal (User): The individual attempting to access a resource.
• Identity Provider (IdP): The system that verifies the user’s identity.
• Service Provider (SP): The system that provides the service or resource the user wishes to access.

SAML provides several constructs to simplify authentication and authorization, including:

• Assertions: Statements made by the IdP about a user’s identity, attributes, and entitlements.
• Protocols: The rules governing the exchange of Assertions between an IdP and SP.
• Bindings: The methods used to transport SAML messages between the IdP and SP.

SAML Authentication Flow

The SAML authentication procedure takes the following steps:

• Access Request: The user attempts to use a resource provided by the SP.
• Authentication Request: The SP redirects the user to the IdP for authentication.
• User Authentication: The IdP authenticates the user’s identity and generates a SAML assertion.
• Assertion Delivery: The IdP sends the SAML Assertion back to the SP.
• Access Granting: After evaluating the assertion, the SP allows the user access to the requested resource.

This procedure is strengthened by the exchange of SAML Assertions, which are XML documents that securely transmit authentication and authorization data.

Implementing SAML Authentication

Integrating SAML authentication into apps requires:

• SP Configuration: Configuring the SP to request and process SAML assertions from an IdP.
• Trust Establishment: Creating trust relationships between SPs and IdPs to ensure the integrity and authenticity of exchanged data.
• Secure Handling: Ensuring SAML responses and assertions are handled securely to prevent unauthorized access.

Benefits and Challenges of SAML

SAML offers significant advantages for enterprise security, including:

• Robust Authentication: Strong authentication mechanisms that verify user identities securely.
• Centralized Control: Centralized access control and user permissions management.
• Enhanced User Experience: SSO capabilities that simplify user access across multiple domains.

However, implementing SAML comes with challenges, such as the complexity of configuration and maintenance and the need for secure XML handling to reduce potential vulnerabilities.

Comparison with Other Authentication Methods

SAML is better suited for cross-domain and enterprise scenarios than other authentication protocols because of its detailed user identity and attribute assertions.

TLS Authentication

Transport Layer Security (TLS) is an important protocol that secures internet connections. It protects privacy and data security between client-server applications that work over a network. TLS’s authentication process is a critical component that verifies the identity of servers (and, optionally, clients) when establishing a secure connection. This feature is essential in HTTPS since it ensures that the communication between a web browser and a server is encrypted and authentic.

How TLS Authentication Works

TLS Authentication is built on the TLS handshake process, which is a series of procedures that allows the client and server to exchange digital certificates securely. This exchange ensures:

• Server Authentication: The server gives its certificate to the client as proof of identity.
• Client Authentication (Optional): The client may offer a certificate if mutual authentication is requested.
• Certificate Authority (CA) Role: CAs are important in issuing digital certificates. Their validation procedure ensures that every certificate presented during the handshake is authentic and trustworthy.

Process of TLS Authentication

The process of securing APIs using TLS involves multiple parts, the most important of which is the TLS handshake, a protocol that allows for the secure exchange of certificates and keys required for encryption and authentication.

• Initiation: The client initiates the handshake by sending a “ClientHello” message, which includes the TLS version, supported cipher suites, and a random byte string for session security.
• Server Response: With a “ServerHello” response, the server selects an encryption method and sends a digital certificate with the public key required for the client to encrypt further communications.
• Certificate Verification: The client validates the server’s certificate using a list of trusted certificate authorities (CAs). This critical stage must be completed to establish trust in the server’s identity.
• Client Authentication (Optional): When client authentication is required, the server will ask the client to provide a certificate. The client then sends its own certificate, which the server verifies, just as it validated the server’s certificate.
• Key Exchange: Following successful authentication, the client and server exchange keys to establish a secure encrypted session.
• Secure Communication: Once the secure channel is created, all incoming and outgoing data exchanged between the client and server is encrypted to prevent tampering and theft.

Implementing TLS Authentication

Setting up TLS Authentication involves:

• Certificate Acquisition: Get a digital certificate from a trusted Certificate Authority (CA).
• Server Configuration: Install and configure the certificate on your server. Configure the server to request a client certificate to enable mutual authentication.
• Client Configuration: If client authentication is used, ensure the client has a certificate installed to present to the server.
• Web Server and Language Specifics: The configuration steps vary based on the web server (e.g., Apache, Nginx) and the programming language used. Following the best practices recommended for your specific technology stack is essential.

Benefits of TLS Authentication

There are many benefits of TLS Authentication:

• Enhanced Security: This prevents tampering and eavesdropping by encrypting data while it is in transmission.
• Integrity and authentication: Ensures that the data sent and received is not altered and comes from a verified source.
• Trust: Builds trust in internet communications by assuring users that their data is secure.

Example of TLS in Action

Consider an API for financial transactions. To secure sensitive data, the API is set up to require TLS for all communications. When attempting to connect to the API, a client application must provide a valid certificate issued by a trusted CA. After verifying the client’s certificate, the server establishes the encrypted session, guaranteeing that all transaction data are securely transmitted.

Best Practices

• Strong Cipher Suites: Choose cipher suites with powerful encryption and authentication mechanisms.
• Certificate Management: To avoid security breaches, renew certificates regularly and maintain a current list of trusted CAs.
• Up-to-date TLS Versions: Older versions of TLS and SSL are vulnerable to attacks. Enforcing TLS 1.2 or higher guarantees the usage of up-to-date encryption standards.

Comparison with Other Authentication Methods

TLS Authentication is a security protocol operating at a different layer than application-level authentication methods such as OAuth 2.0, OpenID, etc. These methods provide user or service authentication on top of the secure channel, which TLS establishes. To sum it up, TLS authentication is essential for securing the communication channel, but additional authentication methods are required to securely identify the users or services operating over that channel.