Delivery-date: Sat, 15 Feb 2025 04:02:38 -0800
Sender: bitcoindev@googlegroups.com
Date: Sat, 15 Feb 2025 03:37:24 -0800 (PST)
From: Jose Storopoli <jose@storopoli.io>
To: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Message-Id: <94ac8f66-1627-4526-bb34-095361a30fb4n@googlegroups.com>
Subject: [bitcoindev] Announcing Bitcoin BOSD: Standardized Withdrawal Output
 Specification for L2s
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Dear Bitcoin Dev Community, 

I am excited to introduce Bitcoin BOSD (Bitcoin Output Script Descriptor), 
a new specification and open source Rust implementation to simplify 
relay-safe (standardness-guarantee) on-chain withdrawals for Bitcoin Layer 
2 solutions.

Key Features:
- Standardness-by-construction for withdrawal outputs 
- Eliminates ad-hoc standardness rule implementations in L2s 
- Compact representation

Problem Solved:
L2 operators currently risk being unable to process withdrawals if users 
request non-standard transactions (e.g., oversized OP_RETURN). BOSD ensures 
outputs are correct-by-construction according to Bitcoin network's 
standardness rules, abstracting away complex validation logic.

Available on crates.io <https://crates.io/crates/bitcoin-bosd>

Get Involved:
Detailed Specification and Motivation/Rationale: SPECIFICATION.md 
<https://github.com/alpenlabs/bitcoin-bosd/blob/main/SPECIFICATION.md>
Repository: github.com/alpenlabs/bitcoin-bosd
Feedback welcome via GitHub Issues and Discussion; or the mailing list. 

This work emerged from practical challenges faced by myself and Trey Del 
Bonis (GitHub @delbonis) at Alpen Labs, while building validation logic for 
processing L2 withdrawals on-chain for Strata: a Bitcoin-native BitVM-based 
bridge to a ZK-rollup. We believe standardization in this domain will 
benefit the entire ecosystem by reducing fragmentation and improving 
interoperability.
The specification is has a CC0 public domain license, and the Rust 
implementation is MIT/Apache-2.0 double licensed.

The structure of a BOSD consists of:

- 1-byte tag representing a type ID.
- Arbitrary-length cryptographic payload (although practically bounded to 
like
  80 bytes).

Here's a table for the supported outputs. Also note that we can trivially 
extend it by adding more prefixes using the type it byte.

```
| Type | Payload Length(s) | Payload Interpretation | Spend Type    | 
Mainnet Address Prefix |
| ---- | ----------------- | ---------------------- | ------------- | 
---------------------- |
| 0    | ..=80             | `OP_RETURN` payload    | (N/A)         | (N/A) 
                 |
| 1    | 20                | pubkey hash            | P2PKH         | 
`1...`                 |
| 2    | 20                | script hash            | P2SH          | 
`3...`                 |
| 3    | 20, 32            | SegWit v0 hash         | P2WPKH, P2WSH | 
`bc1q...`              |
| 4    | 32                | SegWit v1 public key   | P2TR          | 
`bc1p...`              |
```

Since we strived for compact representation both in-memory and also 
over-the-wire, BOSD does not support checksums or any native error 
correction.

PS: Technically Strata is not a defect L2, since it is a 1-of-N 
trust-minimized bridge, and not a fully trustless bridge.

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<br />Dear Bitcoin Dev Community, <br /><br />I am excited to introduce Bit=
coin BOSD (Bitcoin Output Script Descriptor), a new specification and open =
source Rust implementation to simplify relay-safe (standardness-guarantee) =
on-chain withdrawals for Bitcoin Layer 2 solutions.<br /><br />Key Features=
:<div>- Standardness-by-construction for withdrawal outputs <br />- Elimina=
tes ad-hoc standardness rule implementations in L2s <br />- Compact represe=
ntation<br /><br />Problem Solved:<br />L2 operators currently risk being u=
nable to process withdrawals if users request non-standard transactions (e.=
g., oversized OP_RETURN). BOSD ensures outputs are correct-by-construction =
according to Bitcoin network's standardness rules, abstracting away complex=
 validation logic.<br /><br />Available on <a href=3D"https://crates.io/cra=
tes/bitcoin-bosd">crates.io</a><br /><br />Get Involved:</div><div>Detailed=
 Specification and Motivation/Rationale: <a href=3D"https://github.com/alpe=
nlabs/bitcoin-bosd/blob/main/SPECIFICATION.md">SPECIFICATION.md</a><br />Re=
pository: <a href=3D"https://github.com/alpenlabs/bitcoin-bosd">github.com/=
alpenlabs/bitcoin-bosd</a><br />Feedback welcome via GitHub Issues and Disc=
ussion; or the mailing list.=C2=A0<br /><br />This work emerged from practi=
cal challenges faced by myself and Trey Del Bonis (GitHub @delbonis) at Alp=
en Labs, while building validation logic for processing L2 withdrawals on-c=
hain for Strata: a Bitcoin-native BitVM-based bridge to a ZK-rollup. We bel=
ieve standardization in this domain will benefit the entire ecosystem by re=
ducing fragmentation and improving interoperability.</div><div>The specific=
ation is has a CC0 public domain license, and the Rust implementation is MI=
T/Apache-2.0 double licensed.</div><div><br /></div><div>The structure of a=
 BOSD consists of:<br /><br />- 1-byte tag representing a type ID.<br />- A=
rbitrary-length cryptographic payload (although practically bounded to like=
<br />=C2=A0 80 bytes).<br /></div><div><br /></div><div>Here's a table for=
 the supported outputs. Also note that we can trivially extend it by adding=
 more prefixes using the type it byte.</div><div><br /></div><div>```</div>=
<div>| Type | Payload Length(s) | Payload Interpretation | Spend Type =C2=
=A0 =C2=A0| Mainnet Address Prefix |<br />| ---- | ----------------- | ----=
------------------ | ------------- | ---------------------- |<br />| 0 =C2=
=A0 =C2=A0| ..=3D80 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 | `OP_RETURN`=
 payload =C2=A0 =C2=A0| (N/A) =C2=A0 =C2=A0 =C2=A0 =C2=A0 | (N/A) =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0|<br />| 1 =C2=A0 =
=C2=A0| 20 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0| pubkey =
hash =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0| P2PKH =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 | `1...` =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 |<b=
r />| 2 =C2=A0 =C2=A0| 20 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0| script hash =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0| P2SH =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0| `3...` =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 |<br />| 3 =C2=A0 =C2=A0| 20, 32 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0| SegWit v0 hash =C2=A0 =C2=A0 =C2=A0 =C2=A0 | P2WPKH, P2W=
SH | `bc1q...` =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0|<br />| 4 =
=C2=A0 =C2=A0| 32 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0| =
SegWit v1 public key =C2=A0 | P2TR =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0| `bc1=
p...` =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0|<br /></div><div>```=
</div><div><br /></div><div>Since we strived for compact representation bot=
h in-memory and also over-the-wire, BOSD does not support checksums or any =
native error correction.</div><div><br /></div><div>PS: Technically Strata =
is not a defect L2, since it is a 1-of-N trust-minimized bridge, and not a =
fully trustless bridge.</div>

<p></p>

-- <br />
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bitcoindev/94ac8f66-1627-4526-bb34-095361a30fb4n%40googlegroups.com?utm_med=
ium=3Demail&utm_source=3Dfooter">https://groups.google.com/d/msgid/bitcoind=
ev/94ac8f66-1627-4526-bb34-095361a30fb4n%40googlegroups.com</a>.<br />

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