admin/environment/php extension/openssl

To install the openssl library on Windows

1. Open the php.ini file found in the moodle/apache/bin (if not there then, in folder server/php/)
2. Find the line: ;extension=php_openssl.dll
3. Remove the ; at the beginning of the line
4. Restart apache if necessary

Note: if Moodle fails to create a public key in Admin > Networking > Settings, you'll need to configurate your OPENSSL_CONF path. With Windows File Explorer find openssl.cnf file (usually in your php/extras directory). Rename it as openssl.conf. Then set OPENSSL_CONF in your Windows environment variable (example: C:/wamp/bin/php/extras/openssl/openssl.conf - do not forget the file name in the path, otherwise it doesn't work)

To install the openssl library on Unix

1. You need to recompile PHP from source
2. add --with-openssl to the command line when you run configure