PROJECT: Stand-Alone BIP-322 (Generic Signed Message Format Leveraging Bitcoin Script) CLI App #112

BIP-322 is a proposal originally by Kalle Alm (@kallewoof) to leverage the Bitcoin scripting language (ambiguously just called bitcoin script) to enable the signing of arbitrary messages using the same keys & scripts that Bitcoin uses for transactions.

In particular, BIP-322 extends the old single-key signing of messages (using the now off-by-default signmessage & verifymessage rpc api calls) which only worked with legacy scripts like Pay-to-Public-Key-Hash (P2PKH), to allow signing messages using any Bitcoin script wich can conceivably spend (in particular Pay-to-Witness-Script-Hash (P2WSH).

In older versions of bitcoin-core's bitcoind , this is the way the signmessage and verifymessage calls worked (example from LBTCftCL):

$ bitcoin-cli getnewaddress -addresstype legacy
moKVV6XEhfrBCE3QCYq6ppT7AaMF8KsZ1B
$ bitcoin-cli signmessage "moKVV6XEhfrBCE3QCYq6ppT7AaMF8KsZ1B" "Hello, World"
HyIP0nzdcH12aNbQ2s2rUxLwzG832HxiO1vt8S/jw+W4Ia29lw6hyyaqYOsliYdxne70C6SZ5Utma6QY/trHZBI=
$ bitcoin-cli verifymessage "moKVV6XEhfrBCE3QCYq6ppT7AaMF8KsZ1B" "HyIP0nzdcH12aNbQ2s2rUxLwzG832HxiO1vt8S/jw+W4Ia29lw6hyyaqYOsliYdxne70C6SZ5Utma6QY/trHZBI=" "Hello, World"
true

The goal of this project is to implement BIP-322 signmessage and verifymessage functions as a C++ Command Line Interface (CLI) app, in a form that allows for the offline signing of messages, with no dependencies on bitcoin-core's bitcoind server, but leveraging the more secure and supported bitcoin-core libraries like secp256k1 and likely btcdeb.

Community Project milestones:

• Establish team channels
  • This issue
  • Invite team
    • Summer interns
    • The larger Blockchain Commons community
    • Larger open development community
      • Via [Twitter](https://twitter.com/ChristopherA/status/1527738739329339393
        • Get more RTS
      • Initial letter to Bitcoin-Dev community
      • Identify other key interested parties
  • Private channel on Signal (contact @ChristopherA for invite)
• Schedule Intro call & agenda
  • Team intros
  • Review spec & prior efforts
    • BIP-322
    • BIP-322 PR (and comments) to bitcoin-core
    • Bitcoin Script Debugger (btcdeb)
      • Learning btcdeb
    • BIP-322 Python Script in Jupyter Notebook
  • OTHERS?
  • DECISION: Do we have sufficient critical mass of team members to tackle this project this summer (June-August 2022)?
• Create initial repo (license, CLA, initial documents, uses cases, specs, issues, etc.)
  • Give team write access to repo
• Write Use Cases
  • Initial use cases document at https://hackmd.io/KR5ALrSSQO6eyrnUBJreeA
  • Simple offline use case (sign using a secp256k1 private key)
  • Simple bitcoin use case (sign using an bitcoin address, either a spent transaction or is a UTXO)
  • Simple identity use case (#w3c did:key?)
  • Complex identity use case (#w3c did:btcr2?)
  • Use cases for variants such as P2WSH, P2TR, multisig and PSBT support.
  • Other use cases
• Write Requirements for
  • Proof of Concept or MVP
    • POC/MVP requirements
    • Scope & timeframe
  • Future implementations thoughts (what are we leaving out of POC/MVP?)
• Identify canonical test examples and testing criteria
• Implement POC/MVP
  • Identify lead and assign roles
• Document and publicize POC/MVP
• Explore next steps
  • Post-mortem
    • Identify weaknesses of current implementation and low-hanging fruit as possible next steps.
    • How well did this project work out as a summer internship project? How can we do better?
  • Solicit support from Patrons & other funders for continued development

(This issue follows community discussion at #76 (comment) with @ChristopherA @kallewoof @deymow @shoryak @shikharvashistha @Eunoia172 @wip-abramson @ahmadi-08)