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[2607:f8b0:4864:20::52e]) by gmr-mx.google.com with ESMTPS id d2e1a72fcca58-759c4b703e6si311351b3a.0.2025.07.20.15.38.23 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 20 Jul 2025 15:38:23 -0700 (PDT) Received-SPF: pass (google.com: domain of gmaxwell@gmail.com designates 2607:f8b0:4864:20::52e as permitted sender) client-ip=2607:f8b0:4864:20::52e; Received: by mail-pg1-x52e.google.com with SMTP id 41be03b00d2f7-b170c99aa49so2597014a12.1 for ; Sun, 20 Jul 2025 15:38:23 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCWpg9wKYdP08650yZh5F1FOv1lOEYwzbFJ9tGfCZE0pwQeKBbIE6zB4pPaw7akzJRKgOnw/nMo83tKT@googlegroups.com X-Gm-Gg: ASbGncvjw7bknbKU3rwZhk5vpaAprLxwL7XFywTClHywGar1tsMXtk1oFuV4vzKwaYA fzTTCi8mFUYERmNVM768bKS0YWx4HE/yHBZC0IwozVLKI9WN3lAHf30iMzScLs+iGQ73PypITU0 s04Jx1Q4dJhuEM2Beifms4dQpz8rVY5XnYDaVfM9xCYQktHqie4omioTY+hGP3gDwZVPrOtfgBF DFiB/w= X-Received: by 2002:a17:90b:3d8c:b0:316:3972:b9d0 with SMTP id 98e67ed59e1d1-31c9e5fcacfmr27457001a91.0.1753051103205; Sun, 20 Jul 2025 15:38:23 -0700 (PDT) MIME-Version: 1.0 References: <-k1KNMwmXrdmMxpxMeJHAOYuKpMfeUpx7rqfIkta_NC6f7MtzlOYEdXbAhi-SztejTidNysh40ask8j9JNrzxoh1sUCH4F9tKV6tarkrWrc=@proton.me> In-Reply-To: From: Greg Maxwell Date: Sun, 20 Jul 2025 22:38:10 +0000 X-Gm-Features: Ac12FXxRHVboKHzKegd8gcwAQied1g93C1o6jXUJtw0JGYOqrq5Aq8_VzIxFzMk Message-ID: Subject: Re: [bitcoindev] Human meaningful witness versioning To: Ethan Heilman Cc: conduition , Bitcoin Development Mailing List Content-Type: multipart/alternative; boundary="000000000000479e18063a64048b" X-Original-Sender: gmaxwell@gmail.com X-Original-Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@gmail.com header.s=20230601 header.b=XlARAgOe; spf=pass (google.com: domain of gmaxwell@gmail.com designates 2607:f8b0:4864:20::52e as permitted sender) smtp.mailfrom=gmaxwell@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com; dara=pass header.i=@googlegroups.com Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.5 (/) --000000000000479e18063a64048b Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, Jul 20, 2025 at 9:35=E2=80=AFPM Ethan Heilman wr= ote: > Does anyone remember why BIP-0173 added a special rule to make Witness > Versions legible in this way? It might be useful to document here for > future discussions on address encoding. > I'm not sure what you're referring to there -- there needed to be an _encoded_ version for the purpose of consensus rules. 1xxx addresses have one, for example (which results in them beginning with 1). The reason it's 5 bits is just to avoid needlessly inflating the length of addresses.. as additional versioning, if someday required could be achieved by additional words in the payload. There is a _human readable_ part, but that refers to the "bc" prefix identifying the currency/network, not any of the technical minutia about how the system works. The reason for the human readable part was that there has been instances of funds loss caused by fork coins / altcoins that copied bitcoin wholesale and used the same addresses and we'd hoped that a prefix that was easy to change an unambiguously associated with bitcoin would have a chance of reducing that risk in the future. or to restate: A recipient's script is fundamentally none of the sender's business (except for multiparty contracts or other special cases) -- and so generally we want the sender to be as oblivious of the details of the script as reasonably possible. If the sender has paid to the output the receiver has specified then they've done their part. Any further issues are the recipient's responsibility. If the sender hasn't-- e.g. say they took apart some address and made some custom script without the receivers consent, like turning a taproot pubkey into a legacy address-- then they haven't made a payment to the recipient and they still owe the recipient funds. But this also requires that the payment be on the right network, and while they could be informed outside of the address since it was a frequent cause of errors we thought it critical to embed it. The reason for making the embedding legible was primarily so that altcoins wouldn't just copy the prefix as they had frequently done with the version numbers. (and I believe so far this has proved to be successful, copies have changed the HRP) --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+unsubscribe@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/= CAAS2fgR%2BXccLeZqt0GXP%3Db-cu9ya%3D-pVZred_q6xGCrNKMLy9g%40mail.gmail.com. --000000000000479e18063a64048b Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Sun, Jul 20, 2025 at 9:35=E2=80=AFPM E= than Heilman <eth3rs@gmail.com&g= t; wrote:
Does anyone remembe= r why BIP-0173 added a special rule to make Witness Versions legible in thi= s=C2=A0way? It might be useful to document here for future discussions on a= ddress encoding.

I'm not sure what you= 9;re referring to there -- there needed to be an _encoded_ version for the = purpose of consensus rules.=C2=A0 1xxx addresses have one, for example (whi= ch results in them beginning with 1).=C2=A0 The reason it's 5 bits is j= ust to avoid needlessly inflating the length of addresses.. as additional v= ersioning, if someday required could be achieved by additional words in the= payload.

There is a _human readable_ part, but th= at refers to the "bc" prefix identifying the currency/network,=C2= =A0 not any of the technical minutia about how the system works.=C2=A0 The = reason for the human readable part was that there has been instances of fun= ds loss caused by fork coins / altcoins that copied bitcoin wholesale and u= sed the same addresses and we'd hoped that a prefix that was easy to ch= ange an unambiguously=C2=A0associated with bitcoin would have a chance of r= educing that risk in the future.

or to restate: A = recipient's script is fundamentally none of the sender's business (= except for multiparty contracts or other special cases) -- and so generally= we want the sender to be as oblivious of=C2=A0the details of the script as= reasonably possible.=C2=A0 If the sender has paid to the output the receiv= er=C2=A0has specified then they've done their part.=C2=A0 Any further i= ssues are the recipient's=C2=A0responsibility.=C2=A0 If the sender hasn= 't-- e.g. say they took apart some address and made some custom script = without the receivers consent, like turning a taproot pubkey into a legacy = address-- then they haven't made a payment to the recipient and they st= ill owe the recipient=C2=A0funds.=C2=A0 But this also requires that the pay= ment be on the right network, and while they could be informed outside of t= he address since it was a frequent cause of errors we thought it critical t= o embed it.=C2=A0 The reason for making the embedding legible was primarily= so that altcoins wouldn't just copy the prefix as they had frequently = done with the version numbers.

(and I believe so f= ar this has proved to be successful, copies have changed the HRP)









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