Build status updates for Bitbucket are currently sent using the status API. Standard authentication is provided by bitbucket for build status updates. Bitbucket will authorize anyone with admin privileges to the repo to update the build status using the build status API as long as the same build key is used.

The build key is a means to distinguish one build from another. Anyone with admin access can view this build key and use it to modify the build status.

This is a feature request for Bitbucket to provide a way to authorize applications so that the build status set by one application cannot be modified by any other person or application.