From cdd135554878908f308c50c4bc06775d04911926 Mon Sep 17 00:00:00 2001
From: pm47 <pm.padiou@gmail.com>
Date: Wed, 7 Jun 2023 17:55:14 +0200
Subject: [PATCH] generate swap-in potentiam address

---
 .../acinq/eclair/crypto/LocalKeyManager.scala | 26 +++++++++++++++++--
 .../eclair/crypto/LocalKeyManagerSpec.scala   | 12 +++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/crypto/LocalKeyManager.scala b/eclair-core/src/main/scala/fr/acinq/eclair/crypto/LocalKeyManager.scala
index 161c14416..dc4be6841 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/crypto/LocalKeyManager.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/crypto/LocalKeyManager.scala
@@ -19,7 +19,7 @@ package fr.acinq.eclair.crypto
 import com.google.common.cache.{CacheBuilder, CacheLoader, LoadingCache}
 import fr.acinq.bitcoin.scala.Crypto.{PrivateKey, PublicKey}
 import fr.acinq.bitcoin.scala.DeterministicWallet.{derivePrivateKey, _}
-import fr.acinq.bitcoin.scala.{Block, ByteVector32, ByteVector64, Crypto, DeterministicWallet}
+import fr.acinq.bitcoin.scala.{Block, ByteVector32, ByteVector64, Crypto, DeterministicWallet, _}
 import fr.acinq.eclair.router.Announcements
 import fr.acinq.eclair.transactions.Transactions
 import fr.acinq.eclair.transactions.Transactions.TransactionWithInputInfo
@@ -136,7 +136,7 @@ class LocalKeyManager(seed: ByteVector, chainHash: ByteVector32) extends KeyMana
     Transactions.sign(tx, currentKey)
   }
 
-  
+
   /**
     * Ths method is used to spend revoked transactions, with the corresponding revocation key
     *
@@ -157,4 +157,26 @@ class LocalKeyManager(seed: ByteVector, chainHash: ByteVector32) extends KeyMana
     val localFundingPrivKey = privateKeys.get(fundingKeyPath).privateKey
     Announcements.signChannelAnnouncement(chainHash, shortChannelId, localNodeSecret, remoteNodeId, localFundingPrivKey, remoteFundingKey, features)
   }
+
+  def multisigSwapInAddress(serverPublicKey: Crypto.PublicKey, refundDelay: Int): String = {
+    val userKeyPath = chainHash match {
+      case Block.RegtestGenesisBlock.hash | Block.TestnetGenesisBlock.hash =>
+        DeterministicWallet.hardened(51) :: DeterministicWallet.hardened(0) :: DeterministicWallet.hardened(0) :: Nil
+      case Block.LivenetGenesisBlock.hash =>
+        DeterministicWallet.hardened(52) :: DeterministicWallet.hardened(0) :: DeterministicWallet.hardened(0) :: Nil
+    }
+    val userPrivateKey = DeterministicWallet.derivePrivateKey(master, userKeyPath).privateKey
+    val userPublicKey = userPrivateKey.publicKey
+    val redeemScript = OP_PUSHDATA(userPublicKey.value) :: OP_CHECKSIGVERIFY :: OP_PUSHDATA(serverPublicKey.value) :: OP_CHECKSIG :: OP_IFDUP :: OP_NOTIF :: OP_PUSHDATA(Script.encodeNumber(refundDelay)) :: OP_CHECKSEQUENCEVERIFY :: OP_ENDIF :: Nil
+    val pubkeyScript = Script.pay2wsh(redeemScript)
+
+    val hrp = chainHash match {
+      case Block.RegtestGenesisBlock.hash => "bcrt"
+      case Block.TestnetGenesisBlock.hash => "tb"
+      case Block.LivenetGenesisBlock.hash => "bc"
+    }
+    val witnessScript = pubkeyScript(1).asInstanceOf[OP_PUSHDATA].data
+    val address = Bech32.encodeWitnessAddress(hrp, 0, witnessScript)
+    address
+  }
 }
diff --git a/eclair-core/src/test/scala/fr/acinq/eclair/crypto/LocalKeyManagerSpec.scala b/eclair-core/src/test/scala/fr/acinq/eclair/crypto/LocalKeyManagerSpec.scala
index eb39704c9..da5067f60 100644
--- a/eclair-core/src/test/scala/fr/acinq/eclair/crypto/LocalKeyManagerSpec.scala
+++ b/eclair-core/src/test/scala/fr/acinq/eclair/crypto/LocalKeyManagerSpec.scala
@@ -149,4 +149,16 @@ class LocalKeyManagerSpec extends AnyFunSuite {
     assert(keyManager.htlcPoint(channelKeyPath).publicKey == PrivateKey(hex"b1be27b5232e3bc5d6a261949b4ee68d96fa61f481998d36342e2ad99444cf8a").publicKey)
     assert(keyManager.commitmentSecret(channelKeyPath, 0).value == ShaChain.shaChainFromSeed(ByteVector32.fromValidHex("eeb3bad6808e8bb5f1774581ccf64aa265fef38eca80a1463d6310bb801b3ba7"), 0xFFFFFFFFFFFFL))
   }
+
+  test("generate multisig swap-in address") {
+    val entropy = ByteVector32.fromValidHex("0101010101010101010101010101010101010101010101010101010101010101")
+    val seed = MnemonicCode.toSeed(MnemonicCode.toMnemonics(entropy), "").take(32)
+    val keyManager = new LocalKeyManager(seed, Block.RegtestGenesisBlock.hash)
+
+    val serverPublicKey = PublicKey(ByteVector.fromValidHex("02cd0e2ed9c42af42e0b30e2a0b339c8335bbdc1f895fe552d8e224aedc82d6c88"))
+    val swapInRefundDelay = 144 * 30 * 6
+    val swapInAddress = keyManager.multisigSwapInAddress(serverPublicKey, swapInRefundDelay)
+
+    assert(swapInAddress == "bcrt1qvwc4zcelvlj3pcy97pj09dz2hgq0ptav25nrjm54dt3ch09plxnq6pmjje")
+  }
 }