Webhook authentication best practices
What kind of solutions have you used for authenticating Webhook requests coming to your backend from Marketo? The documentation (http://developers.marketo.com/documentation/webhooks/) totally ignores the subject. This is a bit strange as the documentation describes how to get sensitive user data from an apparently exposed public API. Also, in the forums there are some requests related to using OAuth2 in Webhooks but apparently this feature has not been implemented.
The only idea I can come up with is including a hard coded passphrase in the Webhook's GET or POST request parameters. I guess this is an acceptable solution if the passphrase is long enough and requests are sent over https.
Any comments or ideas?
Mikko