What Is OpenSSL

PKI Certificate Tutorials - Herong's Tutorial Examples

∟What Is OpenSSL

This section describes what is OpenSSL - a cryptography toolkit implementing SSL/TLS protocols and related cryptography standards.

What Is OpenSSL? OpenSSL is a cryptography toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) network protocols and related cryptography standards required by them.

There are 2 ways to use the OpenSSL toolkit:

1. OpenSSL API (Application Programming Interface) - The OpenSSL toolkit has been implemented in most programming languages as an API so that you can access OpenSSL functionalities in your own programs. For example, the OpenSSL API for Python is called "pyOpenSSL" module.

2. OpenSSL CLI (Command Line Interface) - The OpenSSL toolkit has also been implemented in most operating systems as a command with functional sub-commands. For example, the OpenSSL Command on Linux is called "openssl".

The OpenSSL toolkit provides a large number of functions in the following areas:

Creation and management of private keys, public keys and parameters
Public key cryptographic operations
Creation of X.509 certificates, CSRs and CRLs
Calculation of Message Digests
Encryption and Decryption with Ciphers
SSL/TLS Client and Server Tests
Handling of S/MIME signed or encrypted mail
Time Stamp requests, generation and verification

Functions provided in OpenSSL are organized into 110 commands. Below is a list of 5 commands that are directly related to PKI certificates:

ca        Certificate Authority (CA) Management.
genpkey   Generation of Private Key or Parameters.
pkcs12    PKCS#12 file command.
req       Certificate request and certificate generating command.
x509      X.509 certificate data management.

In this chapter, I will provide some tutorials using those 5 commands through the OpenSSL CLI to perform tasks illustrated in the following PKI certificate generation process: