The following will guide you through the process of enabling SSL on a Apache webserver

• The instructions have been verified with OSX El Capitan (10.11.2) running Apache 2.4.16
• The instructions assume you already have a basic Apache configuration enabled on OSX, if this is not the case feel free to consult Gist: “Enable Apache HTTP server (OSX)“

Apache SSL Configuration

Create a directory within /Applications/XAMPP/xamppfiles/etc/ using Terminal.app: sudo mkdir /Applications/XAMPP/xamppfiles/etc/ssl
Next, generate two host keys:

sudo openssl genrsa -out /Applications/XAMPP/xamppfiles/etc/server.key 2048
sudo openssl genrsa -out /Applications/XAMPP/xamppfiles/etc/ssl/localhost.key 2048
sudo openssl rsa -in /Applications/XAMPP/xamppfiles/etc/ssl/localhost.key -out /Applications/XAMPP/xamppfiles/etc/ssl/localhost.key.rsa

Create a configuration file using Terminal.app: sudo touch /Applications/XAMPP/xamppfiles/etc/ssl/localhost.conf
Edit the newly created configuration file and add the following:

[req]
default_bits = 1024
distinguished_name = req_distinguished_name
req_extensions = v3_req

[req_distinguished_name]

[v3_req]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names

[alt_names]
DNS.1 = localhost
DNS.2 = *.localhost

Generate the required Certificate Requests using Terminal.app:

sudo openssl req -new -key /Applications/XAMPP/xamppfiles/etc/server.key -subj "/C=/ST=/L=/O=/CN=/emailAddress=/" -out /Applications/XAMPP/xamppfiles/etc/server.csr
sudo openssl req -new -key /Applications/XAMPP/xamppfiles/etc/ssl/localhost.key.rsa -subj "/C=/ST=/L=/O=/CN=localhost/" -out /Applications/XAMPP/xamppfiles/etc/ssl/localhost.csr -config /Applications/XAMPP/xamppfiles/etc/ssl/localhost.conf

Note: Complete the values C= ST= L= O= CN= to reflect your own organizational structure, where:

• C= eq. Country: The two-letter ISO abbreviation for your country.
• ST= eq. State or Province: The state or province where your organization is legally located.
• L= eq. City or Locality: The city where your organization is legally located.
• O= eq. Organization: he exact legal name of your organization.
• CN= eq. Common Name: The fully qualified domain name for your web server

Use the Certificate Requests to sign the SSL Certificates using Terminal.app:

sudo openssl x509 -req -days 365 -in /Applications/XAMPP/xamppfiles/etc/server.csr -signkey /Applications/XAMPP/xamppfiles/etc/server.key -out /Applications/XAMPP/xamppfiles/etc/server.crt
sudo openssl x509 -req -extensions v3_req -days 365 -in /Applications/XAMPP/xamppfiles/etc/ssl/localhost.csr -signkey /Applications/XAMPP/xamppfiles/etc/ssl/localhost.key.rsa -out /Applications/XAMPP/xamppfiles/etc/ssl/localhost.crt -extfile /Applications/XAMPP/xamppfiles/etc/ssl/localhost.conf

Add the SSL Certificate to Keychain Access.

sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain /Applications/XAMPP/xamppfiles/etc/ssl/localhost.crt

Apache Configuration

Edit the Apache main configuration file /Applications/XAMPP/xamppfiles/etc/httpd.conf and enable the required modules to support SSL :

LoadModule socache_shmcb_module libexec/apache2/mod_socache_shmcb.so
LoadModule ssl_module libexec/apache2/mod_ssl.so

Enable Secure (SSL/TLS) connections

Include /private/Applications/XAMPP/xamppfiles/etc/extra/httpd-ssl.conf

Apache Virtual Host Configuration

Edit the Virtual Hosts file /Applications/XAMPP/xamppfiles/etc/extra/httpd-vhosts.conf and add the SSL Directive at the end of the file:

<VirtualHost *:443>
    ServerName localhost
    DocumentRoot "/Applications/XAMPP/xamppfiles/htdocs"

    SSLEngine on
    SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP:+eNULL
    SSLCertificateFile /Applications/XAMPP/xamppfiles/etc/ssl/localhost.crt
    SSLCertificateKeyFile /Applications/XAMPP/xamppfiles/etc/ssl/localhost.key

    <Directory "/Applications/XAMPP/xamppfiles/htdocs">
        Options Indexes FollowSymLinks
        AllowOverride All
        Order allow,deny
        Allow from all
        Require all granted
    </Directory>
</VirtualHost>

Finally restart Apache using Terminal.app : sudo apachectl restart
Open Safari and visit https://localhost to verify your configuration.

Summary

sudo openssl genrsa -out /Applications/XAMPP/xamppfiles/etc/server.key 2048

sudo openssl genrsa -out /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.key 2048

sudo openssl rsa -in /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.key -out /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.key.rsa

sudo openssl req -new -key /Applications/XAMPP/xamppfiles/etc/server.key -subj "/C=CA/ST=ON/L=Toronto/O=dev/CN={{replaced DNS}}/emailAddress={{replaced email}}/" -out /Applications/XAMPP/xamppfiles/etc/server.csr

sudo openssl req -new -key /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.key.rsa -subj "/C=CA/ST=ON/L=Toronto/O=dev/CN={{replaced DNS}}/" -out /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.csr -config /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}-localhost.conf {{add new conf file for each domain }}

sudo openssl x509 -req -days 365 -in /Applications/XAMPP/xamppfiles/etc/server.csr -signkey /Applications/XAMPP/xamppfiles/etc/server.key -out /Applications/XAMPP/xamppfiles/etc/server.crt

sudo openssl x509 -req -extensions v3_req -days 365 -in /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.csr -signkey /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.key.rsa -out /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.crt -extfile /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}-localhost.conf {{add new conf file for each domain }}

sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain /Applications/XAMPP/xamppfiles/etc/ssl/{{replaced extension}}--localhost.crt