On the basic question of why openssl is not found: Short answer:Some installation packages for openssl have a default openssl.cnf pre-included. Other packages do not. In the latter case you will include one from the link shown below; You can enter additional user-specifics --DN name,etc-- as needed.
From https://www.openssl.org/docs/manmaster/man5/config.html,I quote directly:
"OPENSSL LIBRARY CONFIGURATION
Applications can automatically configure certain aspects of OpenSSL using the master OpenSSL configuration file, or optionally an alternative configuration file. The openssl utility includes this functionality: any sub command uses the master OpenSSL configuration file unless an option is used in the sub command to use an alternative configuration file.
To enable library configuration the default section needs to contain an appropriate line which points to the main configuration section. The default name is openssl_conf which is used by the openssl utility. Other applications may use an alternative name such as myapplication_conf. All library configuration lines appear in the default section at the start of the configuration file.
The configuration section should consist of a set of name value pairs which contain specific module configuration information. The name represents the name of the configuration module. The meaning of the value is module specific: it may, for example, represent a further configuration section containing configuration module specific information. E.g.:"
So it appears one must self configure openssl.cnf according to your Distinguished Name (DN), along with other entries specific to your use.
Here is the template file from which you can generate openssl.cnf with your specific entries.
One Application actually has a demo installation that includes a demo .cnf file.
Additionally, if you need to programmatically access .cnf files, you can include appropriate headers --openssl/conf.h-- and parse your .cnf files using
CONF_modules_load_file(const char *filename, const char *appname,
unsigned long flags);
Here are docs for "CONF_modules_load_file";