A cryptographic nonce is important for confirming that a party is active and fully participating in a protocol exchange. One reason attackers can succeed with many web-page attacks is that it is relatively easy to craft authentic-looking pages that spoof actual sites. Suggest a technique by which a user can be assured that a page is both live and authentic from a particular site. That is, design a mark, data interchange, or some other device that shows the authenticity of a web page.