  We show that state-of-the-art services for creating trusted timestamps in
blockchain-based networks do not adequately allow for timestamping of web
pages. They accept data by value (e.g., images and text), but not by reference
(e.g., URIs of web pages). Also, we discuss difficulties in repeatedly
generating the same cryptographic hash value of an archived web page. We then
introduce several requirements to be fulfilled in order to produce repeatable
hash values for archived web pages.
