I followed the instructions at:
How To Build An Apple Push Notification Provider Server When I run the php script on my MacOSX or on Windows using Parallel desktop,
Yes you need a certificate. THis is explained in the Apple docs. One catch, you will probably need to convert the cert to .pem format. The .pem cert needs to include both the certificate and the RSA private key.
Here is a good site to read: http://www.macoscoders.com/2009/05/17/iphone-apple-push-notification-service-apns/
My pem looks like:
Bag Attributes
friendlyName: Apple Development Push Services:
localKeyID:
subject=/UID=com.my.push.sandbox1/CN=Apple Development Push Services: /C=US
issuer=/C=US/O=Apple Inc./OU=Apple Worldwide Developer Relations/CN=Apple Worldwide Developer Relations Certification Authority
-----BEGIN CERTIFICATE-----
-----END CERTIFICATE-----
-----BEGIN RSA PRIVATE KEY-----
-----END RSA PRIVATE KEY-----