Good morning Kenshiro, > - Soft fork: old nodes see CT transactions as "sendtoany" transactions
There is a position that fullnodes must be able to get a view of the UTXO set, and extension blocks (which are invisible to pre-extension-block fullnodes) means that fullnodes no longer have an accurate view of the UTXO set. SegWit still provides pre-SegWit fullnodes with a view of the UTXO set, although pre-SegWit fullnodes could be convinced that a particular UTXO is anyone-can-spend even though they are no longer anyone-can-spend. Under this point-of-view, then, extension block is "not" soft fork. It is "evil" soft fork since older nodes are forced to upgrade as their intended functionality becomes impossible. In this point-of-view, it is no better than a hard fork, which at least is very noisy about how older fullnode versions will simply stop working. > - Safe: if there is a software bug in CT it's impossible to create new coins > because the coins move from normal block to normal block as public > transactions I think more relevant here is the issue of a future quantum computing breach of the algorithms used to implement confidentiality. I believe this is also achievable with a non-extension-block approach by implementing a globally-verified publicly-visible counter of the total amount in all confidential transaction outputs. Then it becomes impossible to move from confidential to public transactions with a value more than this counter, thus preventing inflation even if a future QC breach allows confidential transaction value commitments to be opened to any value. (do note that a non-extension-block approach is a definite hardfork) > - Capacity increase: the CT signature is stored in the extension block, so CT > transactions increase the maximum number of transactions per block This is not an unalloyed positive: block size increase, even via extension block, translates to greater network capacity usage globally on all fullnodes. Regards, ZmnSCPxj _______________________________________________ bitcoin-dev mailing list bitcoin-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
