Chapter 1, OAuth 2.0 Foundations, contains recipes that will cover the basics of OAuth 2.0 through simple recipes that allow the reader to interact with public OAuth 2.0-protected APIs such as Facebook, LinkedIn, and Google.

Chapter 2, Implement Your Own OAuth 2.0 Provider, describes the way you can implement your own OAuth 2.0 Provider, presenting recipes that help with Authorization Server and Resource Server configurations considering different OAuth 2.0 grant types. It also presents how to effectively work with refresh tokens, using different databases to store access tokens.

Chapter 3, Using OAuth 2.0 Protected APIs, presents recipes that helps to create OAuth 2.0 client applications that are able to interact with all grant types described in the OAuth 2.0 specification. It also presents how to manage refresh tokens on the client side.

Chapter 4, OAuth 2.0 Profiles, explains some OAuth 2.0 profiles and how to implement them using Spring Security OAuth2. These profiles are specified to help with specific scenarios that aren't covered by OAuth 2.0 specifications, such as token revocation and token introspection to allow remote validation. This recipe also provides some recommendations, such as how and when to use cache when using remote validation.

Chapter 5, Self Contained Tokens with JWT, focuses on the usage of JWT as OAuth 2.0 access tokens and how to implement the main extensions for JWT, such as JWS and JWE, providing signature and encryption to protect the content conveyed by a JWT access token. This chapter also presents a nice approach to increase the security of your application by using proof-of-possession semantics on OAuth 2.0.

Chapter 6, OpenID Connect for Authentication, explains the difference between authorization and authentication, and how OAuth 2.0 can help to build an authentication protocol. To illustrate the usage of OpenID Connect, all the recipes presented in this chapter are aimed at client applications instead of building an OpenID Connect Provider.

Chapter 7, Implementing Mobile Clients, covers how to implement OAuth 2.0 native mobile clients using Android as the platform chosen for the recipes. This chapter presents some guidelines specified by the recently published specification named OAuth 2.0 for native apps.

Chapter 8 , Avoiding Common Vulnerabilities, covers ways to better protect the main components considered within an OAuth 2.0 ecosystem.

To run the recipes presented in this book, you will basically need JDK 8, Maven, MySQL, and Redis. JDK 8 can be downloaded at http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html . You can download and read the installation instructions for Maven at https://maven.apache.org/download.cgi. To install MySQL, download the community version for your Operational System (OS) at https://dev.mysql.com/downloads/. Some recipes rely on Redis, which can be downloaded here: https://redis.io/download. To interact with the applications that will be created during the recipes, you also need a tool to send HTTP requests to the APIs presented. The recommended tools are CURL, which can be downloaded at https://curl.haxx.se/download.html and PostMan which can be downloaded at https://www.getpostman.com/.

In addition, so that you can write the code presented throughout the recipes, you will also need a Java IDE and Android Studio for native mobile Client recipes.

This book targets software engineers and security experts who are looking at developing their skills in API security and OAuth 2.0. It is also aimed to help developers who want to pragmatically add OAuth 2.0 support for Spring Boot applications as well as Android mobile applications. Prior programming knowledge and basic understanding of web development is necessary. As this book presents the most recipes using Spring Security OAuth2, it would help to have prior experience with Spring Framework.

In this book, you will find several headings that appear frequently (Getting ready, How to do it…, How it works…, There's more…, and See also). To give clear instructions on how to complete a recipe, we use these sections as follows:

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning. Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Let's create the first web page as index.html inside the src/main/resources/templates directory" A block of code is set as follows:

publicclass Entry {
private String value;
public Entry(String value) 
     { this.value = value;}
public String getValue() 
     {returnvalue;}
}

Any command-line input or output is written as follows:

curl -X POST --user clientapp:123456 http://localhost:8080/oauth/token 
 -H "content-type: application/x-www-form-urlencoded" 
 -d "code=5sPk8A&grant_type=authorization_code&redirect_uri=http%3A%2F%2Flocalhost%3A9000%2Fcallback&scope=read_profile"

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "click on Authorize so you get redirected back to the redirect URI callback."

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