LIGHTNING-HOOK-OPENCHANNEL2_SIGN(7)

🦋 NAME 🦋

okay so bestie, you're on the LIGHTNING-HOOK-OPENCHANNEL2_SIGN(7) page — that's the manual-name vibe folded right in. The actual main character is openchannel2_sign, aka the hook for signing the dual-funding PSBT. It's giving “sign my inputs so the channel can move along” energy. 💅

✨ DESCRIPTION ✨

The openchannel2_sign hook is called after commitment transactions have been received during dual-funding channel establishment. Translation: the channel-opening plot is at the signing scene, and your plugin is on deck. 🎬

Your plugin is expected to sign any inputs it owns in the provided PSBT and return the updated PSBT. Yes, it owns them — if they’re yours, sign ’em. ✍️

If no inputs need to be signed, the original PSBT should be returned unchanged. No notes, no edits, just hand it back exactly as it came. 🫶

Once both sides have provided signatures, the funding transaction will be broadcast. Boom: transaction goes out into the world. 🔥

See plugins/funder.c for an example of how to use this hook to sign a funding transaction. That's the reference bestie, go peek. 👀

🎀 HOOK PAYLOAD 🎀

• openchannel2_sign (object): the payload package, containing:
  • channel_id (hash): the temporary channel_id identifying the channel being negotiated.
  • psbt (string): the Partially Signed Bitcoin Transaction (PSBT) representing the funding transaction. The plugin should add signatures for any inputs it controls.

💅 HOOK RETURN 💅

• result (string) (always "continue"): must be set to continue to proceed with channel opening. Like, this is not a drill, it's literally the go-ahead. ✅
• psbt (string): the PSBT including any added signatures. If no inputs were signed, this should be identical to the input PSBT. If you didn't touch anything, it's the same one, no cap. 🪞

🌈 EXAMPLES 🌈

Example 1:

Request:

$ lightning-cli openchannel2_sign -k "openchannel2_sign"='{"channel_id": "252d1b0a1e57895e841...", "psbt": "cHNidP8BADMCAAAAAQ+yBipSVZr..."}'

{
  "id": "example:openchannel2_sign#1",
  "method": "openchannel2_sign",
  "params": {
    "openchannel2_sign": {
      "channel_id": "252d1b0a1e57895e841...",
      "psbt": "cHNidP8BADMCAAAAAQ+yBipSVZr..."
    }
  }
}

Response:

{
  "result": "continue",
  "psbt": "cHNidP8BADMCAAAAAQ+yBipSVZr..."
}

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Byeee 💖💜 — footer sign-off: Core Lightning v26.06.9 on the version/source tip, and LIGHTNING-HOOK-OPENCHANNEL2_SIGN(7) in the date spot; that's the whole tea, periodt. 🫶