Return-Path: Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id DA3EDC002D for ; Wed, 10 Aug 2022 15:06:10 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id B3880408B1 for ; Wed, 10 Aug 2022 15:06:10 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org B3880408B1 Authentication-Results: smtp2.osuosl.org; dkim=pass (1024-bit key) header.d=gazeta.pl header.i=@gazeta.pl header.a=rsa-sha256 header.s=2013 header.b=ktzkZxok X-Virus-Scanned: amavisd-new at osuosl.org X-Spam-Flag: NO X-Spam-Score: -2.099 X-Spam-Level: X-Spam-Status: No, score=-2.099 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DhtvuHD61Vce for ; Wed, 10 Aug 2022 15:06:09 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org DE42A400A6 Received: from smtpo97.poczta.onet.pl (smtpo97.poczta.onet.pl [213.180.149.150]) by smtp2.osuosl.org (Postfix) with ESMTPS id DE42A400A6 for ; Wed, 10 Aug 2022 15:06:08 +0000 (UTC) Received: from pmq4v.m5r2.onet (pmq4v.m5r2.onet [10.174.32.70]) by smtp.poczta.onet.pl (Onet) with ESMTP id 4M2tYN0mmnzlgbhV; Wed, 10 Aug 2022 17:06:00 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gazeta.pl; s=2013; t=1660143960; bh=zsqAA5QJNOpUvhhnC2Hg/YVPkFNfZhgtN+cs6RPmnQI=; h=From:Cc:To:Date:Subject:From; b=ktzkZxokF8q7JCq0A3cfHTtEfH1e7pB/aRkBA6v4vOyTeT9Kq7Pd7qCqvfaSbYrk/ gW4ubwnubukA8TpbSWA/gtDx2nXwRlesXDD9S6KGHmSj9uPmAn5wEoXTxBAqUq11TV UcuCKl4aQ9j6SczOp8zG6P9x9hxghDajTySn6JUo= Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received: from [5.173.241.34] by pmq4v.m5r2.onet via HTTP id ; Wed, 10 Aug 2022 17:06:00 +0200 From: vjudeu@gazeta.pl X-Priority: 3 To: Ali Sherief Date: Wed, 10 Aug 2022 17:05:59 +0200 Message-Id: <166373835-fcb0adc6e7c70aa2d37a60a977c1af89@pmq4v.m5r2.onet> X-Mailer: onet.poczta X-Onet-PMQ: ;5.173.241.34;PL;2 X-Mailman-Approved-At: Wed, 10 Aug 2022 15:10:25 +0000 Cc: "bitcoin-dev@lists.linuxfoundation.org" Subject: Re: [bitcoin-dev] Regarding BIP322 edge cases X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Aug 2022 15:06:11 -0000 > I suppose in the case of legacy P2PKH signing, a hypothetical OP_CHECKDAT= ASIG can take off the stack and perform an ECDSA p= ublic key recovery You can always perform key recovery for legacy ECDSA: " OP_SWAP = OP_CHECKSIG" is always spendable, for any valid DER-encoded pair. Her= e, if " OP_CHECKDATASIG" works for signat= ure verification BIP, then you only need to provide "" as an inp= ut, the rest could be placed in some output, and your program could easily = compute that. Or you can use "OP_DUP OP_HASH160

OP_EQUALVERIFY OP_SWAP OP_CHECKDATASIG" as your output script, then the signer= has to provide a valid signature, and a valid public key explicitly, but i= f you only have some signature, then you can always recover that key by you= rself. Because if OP_CHECKDATASIG is not handled, then still, signing by scripts c= an handle that, but the Script would be unnecessarily complex. And because = there is no need to introduce OP_CHECKDATASIG on-chain, it can be safely do= ne inside this BIP. > I'm not sure how an OP_RESERVED in an unexcuted OP_IF is going to help im= plement an ECDSA pubkey recovery + DUP/HASH160/EQUALVERIFY hybrid instructi= on. Because if you want to support any script, and you want to add a new opcode= , you have to make it somehow compatible with existing schemes. You have to= assign some byte for OP_CHECKDATASIG or for any new opcodes you want to ad= d. And you don't want to assign just the next free opcode, because you will= get OP_CHECKSIGADD or other opcodes from TapScript, so your script decoder= will no longer handle two script versions at once. Unless you want to make= it also compatible with altcoins like BCH, but I guess it is not needed. On 2022-08-10 15:53:31 user Ali Sherief wrote: > > Backward compatibility. If we don't have OP_CHECKDATASIG, then it has t= o be somehow introduced to make it compatible with "Bitcoin Message". I suppose in the case of legacy P2PKH signing, a hypothetical OP_CHECKDATAS= IG can take off the stack and perform an ECDSA pub= lic key recovery, followed by SHA256/RIPEMD160, kind of like a hybrid betwe= en OP_DUP/OP_HASH160/OP_EQUALVERIFY and OP_CHECKSIG. But the implementations would have to decode the Base58 address into "0x00"= plus the address hash. As the only supported invoice type for the Legacy s= igning methods, this should be straight forward to do. > And we have opcodes like OP_RESERVED, that can be wrapped in OP_IF, then = it is "conditionally valid transaction". I'm not sure how an OP_RESERVED in an unexcuted OP_IF is going to help impl= ement an ECDSA pubkey recovery + DUP/HASH160/EQUALVERIFY hybrid instruction. - Ali On Wed, 10 Aug 2022 04:59:46 +0200, vjudeu@gazeta.pl wrote: > > I'm not sure what is to be gained from adding an opcode > > Backward compatibility. If we don't have OP_CHECKDATASIG, then it has to = be somehow introduced to make it compatible with "Bitcoin Message". And we = have opcodes like OP_RESERVED, that can be wrapped in OP_IF, then it is "co= nditionally valid transaction". It is also possible to assign some unused o= pcode, but then it will be more complex, because in Script, those opcodes m= ake transaction invalid, but inside TapScript, those opcodes are defined as= OP_SUCCESS, and make things automatically valid. > > > On 2022-08-09 22:53:34 user Ali Sherief via bitcoin-dev wrote: > > Although there is a Github issue/PR at https://github.com/bitcoin/bips/= pull/1347 for addressing all the TODO items of BIP322, I decided to throw i= t in the mailing list again to see if anyone else has suggestions for deali= ng with them. > > So in an older copy of the draft at https://github.com/bitcoin/bips/blob/= b6b0126e2d04793ba52a40f05d24538fa3f2c9ad/bip-0322.mediawiki , I found the s= ome TODO items, and I will copy-paste the ones in the Specification section= (for full proofs) here: > > > TODO: How does this interact with as-of-yet-unspecified "Silent Transac= tions"? > > TODO: Some invalid opcode to allow only in various proof types? > > TODO: A way for the initial signer to delegate to another scriptPubKey;= needed for better privacy and CoinJoin/Lightning compatibility > > So to start with, I believe it will be very helpful to limit what opcodes= scriptPubKeys to be elligible to sign from them. The specification already= does so to a point, but in order for these to be recognizable, it's my opi= nion that one of the NOPs should be placed at the beginning of the script t= o activate proof parsing mode. > > Of course, an opcode is not necessary at all, if the program is able to i= nfer from context where the proof is coming from. After all, since they can= not be broadcasted, they can't be mined in blocks, so will never be encount= ered in a full node's usual verifier. I'm not sure what is to be gained fro= m adding an opcode - the only source for real transactions is from P2P-obta= ined blocks, so when a human inputs a signature to be verified, it can chec= k that a real transaction is not being inserted by looking for the invalid = input. > > For Silent Transactions, I have already given my suggestion in the PR, th= at some subsection can be made saying that it can operate with them by usin= g its scriptPubKey (and other stuff that may be necessary - I am not excatl= y sure what goes inside the Witness stack of message_signature). > > In the case of the last TODO, related to delegation to another scriptPubK= ey, I am not quite sure at the moment what to do about it - perhaps you guy= s can place a MAST (two Merkle branches, to be specific) - the first branch= has the original signer's scriptPubKey, the second branch contains the del= egated signer's scriptPubKey. > > - Ali