OAuth comes in two flavors- OAuth 1.0 and OAuth 2.0. These specifications are completely incompatible with one another and cannot be used together: there is no backward compatibility. Which is the most popular? Excellent question! OAuth 2.0 is the most commonly used form of OAuth today. So, from now on, whenever I say ""OAuth,"" I'm referring to OAuth 2.0, as that's what you'll most likely be using.

Need for OAuth Authentication

As a response to the direct authentication pattern, OAuth means that it was developed. HTTP Basic Authentication, which prompts the user for a username and password, popularized this pattern. For server-side applications, Basic Authentication is still used as a primitive form of API authentication: instead of sending a username and password to the server with each request, the user sends an API key ID and secret. Previously, sites would prompt you to enter your username and password directly into a form, and they would log in to your data (for example, your Gmail account) as you. This is commonly referred to as the password anti-pattern.

Federated identity was developed for single sign-on in order to create a better web system (SSO). In this scenario, an end user communicates with their identity provider, who generates a cryptographically signed token and passes it on to the application to authenticate the user. The basic OAuth meaning explains that the application has faith in the identity provider. You're good to go as long as that trust relationship works with the signed assertion.

SAML 2.0, an OASIS Standard released on March 15, 2005, popularized federated identity. The main two components are its authentication request protocol (aka Web SSO) and the way it packages and signs identity attributes, known as SAML assertions as part of OAuth meaning being evolved in years to come. Okta does something similar with its SSO chiclets. We send a message, sign the assertion, and include information about the user and the origin of the message. Put your digital signature on it, and you're done.

SAML

SAML is a browser session cookie granting you access to web apps. It is limited in the types of device profiles and scenarios that can be performed outside of a web browser.

It made sense when SAML 2.0 was released in 2005. But a lot has changed since then. We now have modern platforms for developing web and native applications. Gmail/Google Inbox, Facebook, and Twitter are examples of Single Page Applications (SPAs). Because they make AJAX (background HTTP calls) to APIs, they behave differently than traditional web applications unlike the very OAuth meaning of inception. API calls are also made by mobile phones, TVs, gaming consoles, and IoT devices. SAML SSO isn't very good at any of these.

OAuth and APIs

A lot has changed in how we build APIs as well as evolved in OAuth meaning. People invested in WS-* in 2005 to build web services. Most developers are now using REST and stateless APIs redefining the OAuth meaning. In a nutshell, REST is a set of HTTP commands that send JSON packets across the network.

Developers frequently create APIs. The API Economy is a popular ringing word in today's boardrooms. Companies must protect their REST APIs so that many devices can access them. Previously, you'd enter your username/password directory and the app would log in as you. This resulted in the delegated authorization issue.

""How can I give an app access to my data without giving it my password?"" That's what we're talking about if you've ever seen one of the dialogues asking for authentication as OAuth meaning. Well! There is an application requesting permission to access data on your behalf. Well! this is OAuth. OAuth's meaning & key need is a framework for delegated authorization for REST/APIs. It allows apps to gain restricted access (scopes) to a user's data without revealing the user's password. It separates authentication from authorization and supports a variety of use cases addressing various device capabilities. It supports server-to-server applications, browser-based applications, mobile/native applications, and consoles/TVs.

This is similar to hotel key cards, but for apps. You can enter your room if you have a hotel key card. How does one obtain a hotel key card? To obtain it, you must first complete an authentication process at the front desk. You can access resources throughout the hotel after authenticating and receiving the key card.

To put it simply, OAuth is where the following events occur:

1. The app requests permission from the user.
2. The user authorizes the app and provides proof.
3. To obtain a Token, the app must present proof of authorization to the server.
4. The Token can only access what the User has authorized for the specific App.

OAuth Central Components

While in the quest for a functional OAuth meaning, it is deemed to understand that OAuth is founded on the following key components:

• Consent and Scopes
• Actors.
• Clients.
• Tokens.
• Flows. Authorization Server.

OAuth Meaning & Scope in Authentication

When an app requests permission, it displays scopes on the authorization screens. They are collections of permissions requested by the client when requesting a token. When writing the application, the application developer codes these.

Scopes decouple policy decisions about authorization from enforcement. This is the first important aspect of OAuth and its very OAuth meaning. The permissions are prominently displayed. They are not hidden behind an app layer that must be reverse-engineered. They're frequently listed in the API documentation: here are the scopes that this app requires.

You must document this consent while defining OAuth meaning. This is referred to as trust on first use. It's a significant change in the web's user experience. Prior to defining an OAuth meaning, most people were only used to name and password dialogue boxes. You now have a new screen that you must train users to use. Retraining the internet population is difficult. This flow is unfamiliar to many users, ranging from tech-savvy young people to grandparents of older generations who may not be familiar with OAuth's meaning. It's a new concept on the web that has risen to prominence and given new OAuth meaning. You must now authorize and obtain consent.

The consent can vary depending on the application. It can be a time-sensitive range (day, weeks, months), but not all platforms allow you to specify the duration. When you consent, keep an eye out for the app doing things on your behalf, such as LinkedIn spamming everyone in your network. Because it is per application, OAuth is an internet-scale solution. You can frequently log in to a dashboard to see what applications you've granted access to and revoke consent.

OAuth Key Actors

The following are the actors in defining OAuth meaning:

• The data in the resource server is owned by the resource owner. I'm the Resource Owner of my Facebook profile, for example.
• The API that stores the data that the application wants to access.
• Client- The application requesting access to your data.
• Authorization Server- The main OAuth engine.

Thus, OAuth is an authentication protocol that allows users to approve applications to act on their behalf without sharing their passwords. This allows for secure authentication and authorization without the need to store and manage sensitive user credentials.