The SVN annotate feature is quite powerful and makes quick work of who to track down for a particular feature on a particular line of code. This feature is rendered slightly more limited (but still useful) if users access SVN via http. There are no credentials exchanged this way so the annotation shows no name for a line modified by by a developer who uses http to commit a change.
The question is, is there a way for a developer to pass credentials of some sort to SVN on the server to uniquely identify their commit? It is merely the presence of an ID that is required in this environment. Alternate methods such as svn+ssh and file protocols are not available. Finally, this server is on an internal LAN, not public. Tips for https also welcome.
The SVN server is running on Linux with Apache2.