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API Authentication Methods

In this article, I will discuss API authentication methods. Before that, you have to understand what the meaning of the word Authentication is. After that, you will get a detailed description of different authentication APIs.

However, before understanding the meaning of authentication more important thing is you should be aware of what isn’t authentication. There is another term authorization you should be aware of. One thing that is crucial to keep in mind that you can’t rely on the only single authentication method. So that is why there is a need for a variety of API authentication methods. So without wasting time let’s come to a point.

What is Authentication and how different from Authorization?

In simple words, Authentication is a process that checks or verifies the identity of a user who tries to access any network, system, or device. In addition, some access control mechanisms usually verify the username and password to get the identity of the user. For example, to access your email you have to provide credentials such as username and password to log in.

API Authentication Methods
API Authentication Methods

If the credentials are correct you are allowing the website to know who are you and it is your identity that is accessing the website. Some other examples are four or six-digit passcode for mobile unlocking, login password for your computer. Now day’s biometrics is useful for smartphones. Whereas Authorization is a process that determines the rights associated with a particular identity, which means what a user can do.

Why Authentication is useful?

According to you why we require authentication. What do you think about it? Let me help you to understand. Say you have access to some important information and others shouldn’t have to know about it because such a situation can lead to harm to you. So that kind of way that doesn’t allow unauthorized people to access your sensitive information is authentication and we want it.

API Authentication Methods

Authentication is very important in today’s scenarios because now a day, there is a lot of increase in cybercrime. When authentication isn’t secure then hacker mainly tries to get system access and steal sensitive information. There are few examples of cybercrimes like Equifax, Adobe, and Yahoo data breach due to poor authentication.

What are the different types of Authentication?

Due to increased cyber attacks, different types of authentication methods have been developed. Let’s have look at them.

  • Password authentication method
  • Two- factor authentication
  • Multifactor authentication
  • Certificate authentication
  • Token authentication
  • Biometric authentication
  • Transaction authentication
  • Computer Recognition authentication
  • Single Sign-on

Also Read Top Python Libraries You must know in 2021

What is API Authentication and why it matters?

So till now, you got knowledge about what is Authentication and why it is important. Now next question arises what is an API. API is a software protocol and you can say it is a tool using which clients and servers communicate.

But how the server will come to know that the client is a real one. API Authentication is a process that certifies user identity who tries to access server resources. In simple words, you can say API is a way to request data or receive data from an endpoint. API authentication protects malicious data submission and acts as a security layer.

API Authentication methods

We are having numerous API authentication methods. I am sharing a few of them here and discussing in detail as follows:

  • HTTP Basic Authentication
  • API Key Authentication
  • OAuth Authentication
  • OAuth 1.0
  • Bearer Authentication
  • OAuth 2.0
  • OpenID Connect
  • LDAP Authentication Advanced
  • Digest Authentication
  • Hawk Authentication
  • AWS Signature
  • NTLM Authentication
  • Akamai EdgeGrid
  • HMAC Authentication

Let me introduce each of these API authentications.

Also Read A Complete Tutorial on How to secure WordPress Login Page

HTTP Basic Authentication

It is simpler Authentication but you can’t give your password to someone else. The technique used for this method makes use of Base64 encoding. The username and password need to combine together to form a value. The HTTP header Authorization is useful to pass the single value formed from username and password.

API Authentication Methods
API Authentication Methods

Whenever a user makes a request the server on checking the Authorization header makes a comparison of it with credentials stored at its system. The client request satisfies if the credentials and header details match. On the other hand, if there is a mismatch in credentials and header details then a request denial message is forward and authentication gets fails.

You can say this Authentication is useful for checking Proxy-Authorization. In other words, you can consider this authentication as such as you just have to send username and password for API call. For an instance, Mailchimp and Twilio use Basic Authentication. This method is beneficial for HTTP and HTTPS requests.

Such a method is useful for web applications to apply for protection over them using single password protection. This method is not useful without SSL but can combine with other security methods.

API Key Authentication

The key Authentication method makes use of an API key to provide access to a particular service and routine. This method was introduced to overcome the shortcomings of HTTP basic authentication as the credentials were shared.

In this method, you can make use of an API key that consists of a series of letters and numbers. You have to combine the request header or request a URL with the API key. To gain access to data users make use of the API key and the server checks identity of the user. The public key and private key can make use according to need.

Public keys lemmatize the number of users to access a particular function and private key works like a password. This method is highly secure and reliable as a unique key is used. Stripe and Sendgrid make use of API keys.

API Authentication Methods
API Authentication Methods

It is beneficial for both HTTP and HTTPS protocols. In case when initial authentication fails down this method provides limited access also. For more security you have to follow some important points as follows:

  • Always try to use the HTTPS protocol
  • Try to make use of a simple API key
  • Do try to avoid exposure to information using URLs.
  • Make use of hash passwords.
  • Remember to use parameter validation.

OAuth Authentication

This method makes use of authentication and authorization together. It came into existence in 2007. It allows applications to communicate with the API server to gain access. In this method, you can request token-based authentication.

API Authentication Methods

The client sends its request to the authentication server to process it. This approach is very secure and powerful as compared to others. It is useful for various clients and applications. This method makes use of time-limited tokens.

It is compatible with HTTPS protocol. In this method, you just have to press the sign-in button to grant permission and quickly the app authenticates the user request. This method provides you the best user experience. Google, Facebook, and Twitter use this method. The idea behind using OAuth is that the end-user needs not to share its credentials with anyone.


  • The protocol is a revision to OAuth1.0A.
  • It is also called as the Digest Authentications Scheme.
  • It is completely secured, tested, and very popular authentication.
  • This method is based on signatures and makes use of the cryptographic signature.
  • The signature used in this method is a combination of token secret, nonce, and information requested by the user.
  • You can use this method with or without SSL.
  • This version is more complicated as compared to OAuth2.0.


  • It provides 4 types of grants.
  • In this technique, you needn’t make use of a keyed hash for making each call.
  • It makes use of two tokens that access token and refresh token.
  • This method is best in case of identifying a personal user and grants him any access.
  • This authentication method allows the third party to gain limited access to an HTTP service.
  • The method used is more secure as it makes use of a token that you can revoke after some time.
  • This is a more powerful authentication as attackers aren’t able to use the same token again.
  • Try to make use of this method with flows enabled so that it can support server to server and device authentication.
  • This method works with four flows which are authentication code flow, implicit flow, resource owner password flow, and client credentials flow.

Bearer Authentication

In this method, you can make use of security tokens called bearer. This method is also known as Token Authentication which makes use of HTTP authentication. The token used in this technique is a cryptic string which allows user to access particular resource and URL. The bearer token is provided by the server when then the user requests a login. To request protected resources, the client sends the token to the authorization header. It is useful only for HTTPS protocols. In RFC-6750 this authentication was generated as part of it.

API Authentication Methods

OpenID Connect

It is a plug-in that is available for many customers and gives support to various credentials like:

  • Signed JWT Access Tokens
  • Opaque access Tokens
  • Session cookie credentials
  • Authorization Code using OpenID
  • Client ID and secret for credential grant
  • Username and password for password grant

This method acts as a relying party and proxy for OAuth 2.0 resource users. It acts as an identity layer on the top of OAuth2.0. This method verifies the identity based on authentication of the authorization server. It is useful to verify end-user identity based on authentication which makes use of JSON web token called ID token.

The authorization server also reveals the profile information of the end-user. This authentication makes use of JSON to specify a RESTful HTTP API. You can make use of this method to get information about the authenticated session. This method is beneficial for web-based, mobile, and JavaScript clients.

An additional feature of this method includes encryption of identity data, OpenID provider’s information, and management of session. This method makes use of a Sign-in flow that provides useful information like username and email id. In OpenID connect there is an OpenID Connect discovery in which the server of OpenID publishes metadata.

JWT is used in this method having the following features:

It is a JSON web token that is open and based on industry-standard RFC 7519. It is easy to use and setup. In this token, manual management of token creation is a must task as it is used for a secure representation of claims between two parties. It is more secure than API key authentication as it allows you to decode and verify JWT. It is developed by Autho which is an authentication Management Company and API-driven identity.

LDAP Authentication Advanced

This authentication method is available by Kong Enterprise that enables LDAP bind authentication. This method enables service, route, or previous versions of Kong. It acts as a global plug-in and runs after receiving a request. This technique allows provides limited access to an anonymous user when authentication fails.

API Authentication Methods
API Authentication Methods

Digest Authentication

In this method, the client requests API. The server in the response of request provides nonce, a realm value, and a 401 unauthorized response. After that, the user sends back an encrypted data array containing the username, password, and server response data.

The server compares the user request with an encrypted string made from data send by the user. This method is useful for web servers to negotiate credentials. Such type of method is useful in cases where there is a need to confirm user identity before sharing sensitive information with him.

API Authentication Methods

It is used by various online banking systems. A hash function is applied to the username and password. It uses HTTP protocol and reversible Base64 encoding. This method was developed by Phillip Hallam banker at CERN in the year 1993.

This scheme uses MD5 cryptographic hashing and nonce to protect the user from a replay attack. In this method, the server isn’t provided a clear password. This method reduces the chances of Phishing. Digest authentication can be attacked through man in the middle attack. This scheme uses a less strong password hash.

Hawk Authentication

This method makes use of partial HTTP request cryptographic verification, request URI, and host. You have to enter Hawk Auth ID, Auth key, and algorithm fields. In this method, the MAC (message authentication code) algorithm is used to make an HTTP request. It makes use of user credentials including the identifier and key to be used in the MAC algorithm.

API Authentication Methods
API Authentication Methods

To apply the hawk scheme you need to provide a shared symmetric key to the client and server. The shared credentials are provided through a TLS protected phase. This method is used to improve basic HTTP authentication. Hawk authentication is used to secure the credentials and avoids their exposure to a malicious server.

To provide secure communication this method makes use of timestamp. The client needs a token id and key from the server to sign the requests. Hawk authentication can be used in pyramid application and node.js express apps. The real-time use example of hawk authentication is in Mozilla services. This method is compatible with drupal8. Its first version was provided by Eran Hammer in November 2012.

AWS Signature Authentication

This authentication is used in Amazon web Services. It makes use of a custom HTTP scheme that is based on keyed-HMAC for authentication purposes. Other parameters followed in this method are the AWS region, service name, and session token. AWS signature authentication allows:

  • To verify the identity of the requester.
  • It provides in-transit data protection.
  • To protect the reuse of signed portions of requests.
API Authentication Methods

In this method, authentication information can be provided by either an HTTP authorization header or using query string parameters. First of all, you have to send an authentication request including a signature. In AWS authentication you needn’t use a secret access key to sign any request.

Instead of using its secret access key, this method makes use of a secret access key to create a signing key. The signing key remains under a specific domain and never gets expired. On receiving an authentication request, the Amazon server recreates the signature. The request is accepted if both signs are matched, otherwise, the request is rejected.

NTLM Authentication

It is an authorization flow used in the windows operating system and for standalone applications. This method is also known as Windows challenge/Response. Few other advanced parameters to be used for this authentication are domain and workstation. It is used for login authentication and makes use of domain name, user name, and a hash of the user’s password.

API Authentication Methods

In this scheme, you needn’t send a user password for authentication purposes. NLTM authentication uses two systems as follows:
• Client system- it is used for making authentication requests.
• Domain controller- it saves information related to user password.

In the case of non-interactive authentication, you only need the client, server, and domain controller. Using this method, the user provides some information to the client computer like domain name, password, and user name. In return, the client computer generates the cryptographic hash.

The client sends a username in form of plain text to the server. The server creates a nonce and sends it back to the client. Now new secured NTLMv2 is introduced which protects brute-force and replay attacks. This method is used by windows NT4.0 OS as the default network authentication protocol.

This authentication protocol is created by Microsoft and initially was a proprietary protocol. It is used as an SSO (single sign-on) process that uses MD4 for password encryption.

Akamai EdgeGrid Authentication

  • This is used as an authorization helper which is developed by Akamai.
  • To use this method you have to enter the access token, client token, and client secret.
  • You need to make a proper authentication request to use this method.
API Authentication Methods

HMAC Authentication

This is known as hash-based message authentication. In this method, an authentication code is generated with the combination of secret key and hashing function. The authentication method is used for checking the message’s authenticity and integrity. The method is used mostly by Amazon Web Services.

API Authentication Methods
API Authentication Methods

This method uses two important things as the first is the secret key and the second is a key identifier. The authentication method signs the whole request which can have MD5. To use the method you needn’t use SSL. The method is similar to digital signatures.


Here in this article, I have shared many API authentication methods with you. Do try to find which method is used most? There was a survey of more than 100 API and it was discovered the widely used method is OAuth 2.0. Basic authentication is also a good choice but it is more vulnerable to hijacks because it doesn’t make use of any encryption.

In some cases users also make use of OpenID connect that is OAuth2.0 based. The popularity of Oauth2.0 is due to the reasons that it is easy to use and provides scalable security by making use of RSA encryption. The implementation cost is even also low.

I am not saying that you just have to use OAuth 2.0. You can choose the authentication method according to your requirement. The only thing that matters is the chosen method should be beneficial for you. I hope the article is informative for you and provides you a lot of information about the API authentication methods. So stay tuned and keep commenting on the article. Don’t forget to give your valuable suggestions.

Anjali Saini
Anjali Saini
A hardworking person, always adventurous about learning new things. Aiming to develop new skills and passion for computer technology.


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