1. A method comprising: transmitting a markup language page comprising a link that corresponds to a resource hosted by a server; transmitting information indicative of a time-based transformation of the link; receiving a request to access the resource, the request comprising a first transformed version of the link; forming a second transformed version of the link based at least in part on the time-based transformation and a time the request to access the resource was received; and authorizing access to the resource based at least in part on determining that the first transformed version of the link corresponds to the second transformed version of the link.