Working with the OpenSSL command line

On the Ubuntu Linux distribution, OpenSSL is usually already available. However, it can be installed using the following commands:

$ sudo apt-get install openssl

Examples in this chapter have been developed using OpenSSL version 1.0.2t. It is available at https://packages.ubuntu.com/xenial/openssl. You are encouraged to use this specific version, as all examples in the chapter have been developed and tested with it. The OpenSSL version can be checked using the following command:

$ openssl version

If you see the following output,

OpenSSL 1.0.2t  10 Sep 2019

then you are all set to run the examples provided in this chapter. If you are running a version other than 1.0.2t, the examples may still work but that is not guaranteed, especially as older versions lack the features used in the examples and newer versions may not be backward compatible with version 1.0.2t.

In the sections that follow, the theoretical foundations of cryptography are first discussed and then a series of relevant practical experiments will be presented.