Systems, methods, and apparatuses associated with data exchanged between a processor and a hardware accelerator are disclosed. In various embodiments, a method comprises receiving, at a first endpoint, a first request to change a current tag frequency used to generate a first authentication tag for one or more transactions of a first transaction window sent over a data link to a second endpoint coupled to a processor core. The method further includes sending a message to the second endpoint that the current tag frequency is to change to a new tag frequency, where a second authentication tag for one or more transactions in a second transaction window is to be generated based on the new tag frequency. The method also includes changing the current tag frequency to the new tag frequency based, at least in part, on receiving an acknowledgement that the second endpoint received the message.