How to enable PHP's openssl extension to install Composer?

For WAMP server, comment given by "Enrique" solved my problem.

wamp is using this php.ini:

c:\wamp\bin\apache\Apache2.4.4\bin\php.ini

But composer is using PHP from CLI, and hence it's reading this file:

c:\wamp\bin\php\php5.4.12\php.ini (so you need to enable openssl there)

For composer you will have to enable extension in

c:\wamp\bin\php\php5.4.12\php.ini

Change:

;extension=php_openssl.dll 

to

extension=php_openssl.dll