Get User Informations with API

To finish the Wordpress-Authpuppy plugin, I need to obtain the user informations with the API.

User information :
- Username
- Password
- E-mail

Using a specific method using the username or password as parameters

http://myserver/ws/?&action=GetUserInfo&username=the_username
http://myserver/ws/?&action=GetUserInfo&email=the_email

{"result":
    1,
    "values":
         {
              "username":"the_username",
              "password":"the_password",
              "email":"the@email",
         }
}