Authentication options available in Servlets:

There are four different options for authentication in servlets

1. Basic Authentication- In this the server uses the username and password provided by the client to authenticate the user. The server gives several attempts (up to 3 attempts) after the three wrong attempts it gives the error page (usually an HTTP 401 Unauthorized error).

2. Form-based authentication- In this the login form is made by the programmer by using HTML. This is more helpful than the basic authentication because we can create more login interface other than username and password for the authentication.

3. Digest Authentication- It is similar to basic authentication but in this the passwords are encrypted using Hash formula. This makes digest more secured.

4. Client certificate Authentication- It requires that each client accessing the resource has a certificate that it send to authenticate itself. This requires SSL protocol.