Can anybody explain the term "anonymous admissible timestamp" to me? Could you show a case where it is useful to apply it?
I came across this term in the comments of a question on the StackExchange Computer Science site.
What he meant is quite unclear. It could be that he's referring to a Timestamping Authority (TA) (See related RFC like 3161). What they do is basically sign a document/hash with the current time and date and sequential transaction id (IIRC).
Ideally, the TA is public and anonymous, allowing anyone to submit any hash and get a signed timestamp for it, the list of signed transaction freely available for anyone to check and verify.
If I refer to the scenario, the bar could issue anonymous 'tickets' containing a unique and untraceable identifier, meaning the bar doesn't keep tabs (pun intended) to whom a given identifier belongs to. In practical terms, they might just have a check to avoid giving multiple tickets to the same person. When the user wants to get his beer, he gets a stamp from the TA by submitting the ticket content (or hash thereof), and forward the stamp to the bartender. Receiving the stamp, the bartender execute a lookup request to match the ticket to all the related transactions and check the date of the two last transactions (validating the stamp signature as well obviously). If they are separated by at least an hour, the stamp is deemed valid.