Micro Focus Demo CA comprises a set of scripts which use the openssl utility program. This utility is included in the Enterprise Developer and Enterprise Server products. Some operating systems also include a version of the openssl utility; for Demo CA, you should use the version supplied by Micro Focus to avoid any issues with differences among OpenSSL versions.
OpenSSL is an implementation of SSL/TLS and related tools maintained by the OpenSSL Project (openssl.org). Micro Focus includes customized portions of the OpenSSL distribution in Enterprise Developer. The openssl utility offers a number of functions which are useful for SSL/TLS and PKI tasks, such as creating and manipulating key and certificate files.
Additional documentation about OpenSSL can be found on openssl.org and other websites.