To get the most out of this book

You will have to install OpenSSL on your computer in order to run the command-line and C code examples. If you haven’t installed it yet, Chapter 2, Symmetric Encryption and Decryption, will help you to do so. To build the C code examples, you will need a C11-compatible C compiler and a linker. You will have to install these development tools following their respective documentation. All the examples have been tested on Kubuntu Linux 22.04 using GNU C Compiler, GNU Linker (LD), and GNU Make from the Linux distribution mentioned. Other development tools, such as LLVM Clang or Microsoft Visual C++, should also be compatible with the code examples in this book.

If you are using the digital version of this book, we advise you to type the code yourself or access the code from the book’s GitHub repository (a link is available in the next section). Doing so will help you avoid any potential errors related to copying and pasting code.

While explanations of OpenSSL features and code examples are sometimes very detailed, the book is meant to provide guidance, not to replace the OpenSSL documentation. If you are wondering about details of OpenSSL functionality that are not covered by the book, feel free to consult the OpenSSL documentation, the OpenSSL source code, or just experiment with your own code using OpenSSL!