A method for protecting a digital document and user data typed into a digital document is presented. The method comprises computation of an authentication tag when the document is sent from a server. A similar authentication tag is computed when the document is shown on a client. When another document referenced in the document is requested by the client from the server, the authentication tag computed by the client is attached to the request for that other document. The server receiving the request compares the authentication tag it computed with the one it received to verify if the request came from an authentic copy of the document. The method is suitable for protection of online banking, online investment, online shopping, and other electronic applications.