The entire content server, including its API uses HTTP Auth in either basic or digest mode. There is no other form of authentication.
You tried basic the server might be using digest (there are options in the server preferences to control this)
See for example:
Code:
curl --digest --user username:password http://localhost:8080/ajax/library-info
{"library_map": {"test_library": "test library", "library": "library", "erolib": "erolib", "demo_library": "demo library", "largelib": "largelib"}, "default_library": "test_library"}