I would like to check how many block confirmations are needed to be considered confirmed? Previously there was an answer that suggested 30 blocks (~ 30 minutes) Is this the recommended number? I have also read that tendermint is going to be implemented on tezos which allows instant confirmation have this been implemented?
This depends on what assumptions one makes on the stake an attacker trying to revert a transaction/block has, on the exact question one asks, on the degree of confidence one would like to have, and on further assumptions about the behavior of the network... For a more detailed answer see this blog post: https://blog.nomadic-labs.com/analysis-of-emmy.html.
Suppose we're trying to answer this question: my transaction was included
x blocks ago (that is, there are already
x confirmations), can I now be sure the block with the transaction remains on the main chain? And suppose that the chain is healthy (all
x blocks have no delay, that is, they come 1 minute one after the other). Then the numbers
x of confirmations are as follows:
- 3 confirmations, for 20% attacker stake
- 5 confirmations, for 30% attacker stake
- 12 confirmations, for 40% attacker stake
(These numbers were obtained with a similar analysis as in the blog post, even though they do not appear as such there.)