Since Java 6, the JRE ships with a simple built-in HTTP/S server. This implementation includes support for authentication mechanisms, and also includes HTTP Basic auth.
This projects implements the more secure Digest auth; that said, it is by no means a proper replacement for HTTPS, but may be useful for scenarios where HTTPS is not a possibility.
Extend the com.joseprio.httpserver.DigestAuthenticator class and
implement the gethAuthToken(String user) method; this method should
return the HA1 string for the specified user. The HA1 string is
the result of applying MD5 to a string composed by
<<user>>:<<realm>>:<<password>>. A helper method
calculateAuthToken(String user, String password) is provided in
order to calculate the HA1 string if you've access to the password
in plaintext.
A simple implementation is included in the
com.joseprio.example.DigestHttpServer class; it may be run from
the command line or from your favorite IDE.