Liam,
Thx for your proposal. Unix C++ user can use the already existing BaseX API, that unfortunately don't work for poor Windows users.
My program do send information to BaseX server, since the server replies through its log "admin (the user account I am using to log in) -- acces denied". There is probably something in the MD5 algorithm that I am using. However, I checked that the MD5 algorithm computes correctly the hash for 'admin'.
If BaseX server could echo the incoming request, that would be of great help, but I don't know how to do this. If nobody knows, I will have to fork the BAseX code and to try compile a server to see what is happening on the server side...that is probably some days of hard works :(