From 6a5a10546a183ac8556230393a98010645ae9baa Mon Sep 17 00:00:00 2001
From: fbock <fbock@student.42heilbronn.de>
Date: Wed, 14 Aug 2024 18:38:31 +0200
Subject: [PATCH] working on client musig partitial sig

---
 taptrade-cli-demo/trader/src/trading/mod.rs   |  4 +--
 taptrade-cli-demo/trader/src/wallet/mod.rs    | 27 +++++++++++++++----
 .../src/wallet/{musig2.rs => musig2_utils.rs} | 14 +++++-----
 3 files changed, 31 insertions(+), 14 deletions(-)
 rename taptrade-cli-demo/trader/src/wallet/{musig2.rs => musig2_utils.rs} (83%)

diff --git a/taptrade-cli-demo/trader/src/trading/mod.rs b/taptrade-cli-demo/trader/src/trading/mod.rs
index f81f093..523b788 100644
--- a/taptrade-cli-demo/trader/src/trading/mod.rs
+++ b/taptrade-cli-demo/trader/src/trading/mod.rs
@@ -13,7 +13,7 @@ use crate::{
 	},
 	wallet::{
 		bond::Bond,
-		musig2::{MuSigData, MusigNonce},
+		musig2_utils::{MuSigData, MusigNonce},
 		TradingWallet,
 	},
 };
@@ -55,7 +55,7 @@ pub fn run_maker(maker_config: &TraderSettings) -> Result<()> {
 
 		let signed_payout_psbt = wallet
 			.validate_payout_psbt(&payout_keyspend_psbt)?
-			.sign_payout_psbt(payout_keyspend_psbt, agg_pub_nonce, agg_pubk_ctx)?;
+			.sign_keyspend_payout_psbt(payout_keyspend_psbt, agg_pubk_ctx, agg_pub_nonce, local_musig_state: &offer.used_musig_config)?;
 		// submit signed payout psbt back to coordinator
 		panic!("Payout to be implemented!");
 	} else {
diff --git a/taptrade-cli-demo/trader/src/wallet/mod.rs b/taptrade-cli-demo/trader/src/wallet/mod.rs
index 1e9c99e..3a41c02 100644
--- a/taptrade-cli-demo/trader/src/wallet/mod.rs
+++ b/taptrade-cli-demo/trader/src/wallet/mod.rs
@@ -1,5 +1,5 @@
 pub mod bond;
-pub mod musig2;
+pub mod musig2_utils;
 pub mod wallet_utils;
 
 use super::*;
@@ -31,7 +31,9 @@ use bdk::{
 };
 use bond::Bond;
 use cli::OfferType;
-use musig2::MuSigData;
+use hex::ToHex;
+use musig2::secp::MaybeScalar;
+use musig2_utils::MuSigData;
 use serde::Serialize;
 use std::{ops::Add, str::FromStr};
 use wallet_utils::get_seed;
@@ -216,9 +218,10 @@ impl TradingWallet {
 		validated_payout_psbt: PartiallySignedTransaction,
 		key_agg_context: KeyAggContext,
 		agg_pub_nonce: AggNonce,
+		local_musig_state: &MuSigData,
 	) -> Result<String> {
 		let payout_tx = validated_payout_psbt.extract_tx();
-		let sig_hash_cache = SighashCache::new(payout_tx);
+		let mut sig_hash_cache = SighashCache::new(payout_tx);
 
 		let utxo = validated_payout_psbt
 			.iter_funding_utxos()
@@ -232,8 +235,22 @@ impl TradingWallet {
 			.context("Failed to create keyspend sighash")?
 			.as_byte_array();
 
-		panic!("Implement keyspend signing");
+		let secret_nonce = local_musig_state.nonce.get_sec_for_signing()?;
+		let seckey = local_musig_state.secret_key;
 
-		Ok(signed_psbt)
+		let keyspend_sig: musig2::PartialSignature = musig2::sign_partial(
+			&key_agg_context,
+			seckey,
+			secret_nonce,
+			&agg_pub_nonce,
+			keyspend_sig_hash_msg,
+		)?;
+
+		match keyspend_sig {
+			MaybeScalar::Valid(s) => Ok(s.encode_hex()),
+			MaybeScalar::Zero => {
+				return Err(anyhow!("keyspend sig maybe scalar is Zero"));
+			}
+		}
 	}
 }
diff --git a/taptrade-cli-demo/trader/src/wallet/musig2.rs b/taptrade-cli-demo/trader/src/wallet/musig2_utils.rs
similarity index 83%
rename from taptrade-cli-demo/trader/src/wallet/musig2.rs
rename to taptrade-cli-demo/trader/src/wallet/musig2_utils.rs
index 6e19498..d916711 100644
--- a/taptrade-cli-demo/trader/src/wallet/musig2.rs
+++ b/taptrade-cli-demo/trader/src/wallet/musig2_utils.rs
@@ -3,14 +3,11 @@ use crate::wallet::{wallet_utils::get_seed, KeychainKind};
 use anyhow::{anyhow, Error, Result};
 use bdk::bitcoin::secp256k1::PublicKey;
 use bdk::{
-	bitcoin::{
-		bip32::ExtendedPrivKey,
-		secp256k1::{All, SecretKey},
-	},
+	bitcoin::{bip32::ExtendedPrivKey, secp256k1::All},
 	keys::{DescriptorPublicKey, DescriptorSecretKey},
 	template::{Bip86, DescriptorTemplate},
 };
-use musig2::{PubNonce, SecNonce, SecNonceBuilder};
+use musig2::{secp256k1::SecretKey as MusigSecretKey, PubNonce, SecNonce, SecNonceBuilder};
 use std::time::{SystemTime, UNIX_EPOCH};
 
 // https://docs.rs/musig2/latest/musig2/
@@ -19,7 +16,7 @@ use std::time::{SystemTime, UNIX_EPOCH};
 pub struct MuSigData {
 	pub nonce: MusigNonce,
 	pub public_key: PublicKey,
-	pub secret_key: SecretKey,
+	pub secret_key: MusigSecretKey,
 }
 
 // secret nonce has to be used only one time!
@@ -70,10 +67,13 @@ impl MuSigData {
 		let nonce = MusigNonce::generate()?;
 		let keypair = xprv.to_owned().to_keypair(secp_ctx); // double check keypair, which derivation should we use?
 
+		// convert from bdk secp to musig crate secp for the traits needed to do sig agg
+		let musig_type_secret_key = MusigSecretKey::from_slice(&keypair.secret_bytes())?;
+
 		Ok(MuSigData {
 			nonce,
 			public_key: keypair.public_key(),
-			secret_key: keypair.secret_key(),
+			secret_key: musig_type_secret_key,
 		})
 	}
 }