Other TSA than freeTSA

A independent trusted third party is used to confirm the creation time of the key - the Time Stamping Authority, short TSA. Currently UCS is using freeTSA as Time Stamping Authority. We considered to add more TSAs, but however there are some restrictions linked with this topic. I will try to explain why only freeTSA is available until now.

There is a GitHub list of TSA servers:

There are multiple reasons why only freeTSA is supported. As written in the whitepaper it was considered to implement openTSA. OpenTSA stores the hash of a file in a Bitcoin transaction. More detailed it will combine (multi-hash) multiple hashes and stores it as single hash in the purpose description field of a Bitcoin transaction.

The first point is, that a sovereign cryptocurrency should never rely/depend on another cryptocurrency. Second point is that you would have to implement the openTSA client plus a Bitcoin client + full blockchain. And that would require lots (and lots and lots…) of space, so we declined that. Other TSAs on the list however are either commercial (we would have to pay getting accounts timestamped and the number is always limited) or we don’t know if they still will be there in future for free use. If we would allow the user to choose it’s own TSA users could set up manipulated TSAs.

So we need a independent, reliable, but free timestamping authority. Only freeTSA fulfills this requirement from my point of view. If somewhen in the future freeTSA is suddenly out of service of course we have prepared our own TSA to go live then. But this should not be done unless freeTSA is permanently out of service!