From: ZmnSCPxj <ZmnSCPxj@protonmail•com>
To: "Kenshiro \\[\\]" <tensiam@hotmail•com>,
Bitcoin Protocol Discussion
<bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Implementing Confidential Transactions in extension blocks
Date: Mon, 11 Feb 2019 04:29:42 +0000 [thread overview]
Message-ID: <U-ugv1xWdp4czsN38WhD6KQUPcYa4VLxNzUusM3YLRu4825eigldn3xTOw6IyoqpyFbymdKxWUGOQdlknr3L7rBOtssEKeYMkW4RKj5Rc1o=@protonmail.com> (raw)
In-Reply-To: <DB6PR10MB183228F27750132F9A6A3542A6690@DB6PR10MB1832.EURPRD10.PROD.OUTLOOK.COM>
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
next prev parent reply other threads:[~2019-02-11 4:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 10:12 Kenshiro []
2019-02-11 4:29 ` ZmnSCPxj [this message]
2019-02-11 10:19 ` Kenshiro []
2019-02-12 17:27 ` Trey Del Bonis
2019-02-14 22:32 ` Hampus Sjöberg
2019-02-14 21:14 Kenshiro []
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