From 5f82307e272837c00efb945849965d9ecec80801 Mon Sep 17 00:00:00 2001
From: GreyMcCarthy <105063806+GreyMcCarthy@users.noreply.github.com>
Date: Mon, 13 Jun 2022 15:13:48 -0400
Subject: [PATCH] Added Compute Contract Id test Vectors (#4385)

* Testing contract id calculation

* Added implicit json reader imports
---
 .../commons/serializers/JsonSerializers.scala |  2 +
 .../core/protocol/dlc/compute/DLCUtil.scala   | 25 +++++++--
 .../src/test/resources/contract_id_test.json  | 26 +++++++++
 .../wallet/ComputeContractIdTest.scala        | 56 +++++++++++++++++++
 4 files changed, 103 insertions(+), 6 deletions(-)
 create mode 100644 wallet-test/src/test/resources/contract_id_test.json
 create mode 100644 wallet-test/src/test/scala/org/bitcoins/wallet/ComputeContractIdTest.scala

diff --git a/app-commons/src/main/scala/org/bitcoins/commons/serializers/JsonSerializers.scala b/app-commons/src/main/scala/org/bitcoins/commons/serializers/JsonSerializers.scala
index 19167dedee..b89ccf130b 100644
--- a/app-commons/src/main/scala/org/bitcoins/commons/serializers/JsonSerializers.scala
+++ b/app-commons/src/main/scala/org/bitcoins/commons/serializers/JsonSerializers.scala
@@ -44,6 +44,8 @@ object JsonSerializers {
   implicit val doubleSha256DigestBEReads: Reads[DoubleSha256DigestBE] =
     DoubleSha256DigestBEReads
 
+  implicit val sha256DigestReads: Reads[Sha256Digest] = Sha256DigestReads
+
   implicit val ripeMd160DigestReads: Reads[RipeMd160Digest] =
     RipeMd160DigestReads
 
diff --git a/core/src/main/scala/org/bitcoins/core/protocol/dlc/compute/DLCUtil.scala b/core/src/main/scala/org/bitcoins/core/protocol/dlc/compute/DLCUtil.scala
index 22ecd115b0..bea34d25ab 100644
--- a/core/src/main/scala/org/bitcoins/core/protocol/dlc/compute/DLCUtil.scala
+++ b/core/src/main/scala/org/bitcoins/core/protocol/dlc/compute/DLCUtil.scala
@@ -27,6 +27,24 @@ import scala.util.Try
 
 object DLCUtil {
 
+  /** @see https://github.com/discreetlogcontracts/dlcspecs/blob/master/Protocol.md#definition-of-contract_id
+    * @param fundingTxId the id of the transaction that contains the DLC funding output
+    * @param outputIdx the index of the output
+    * @param tempContractId the temporary contractId in the offer message
+    * @return
+    */
+  def computeContractId(
+      fundingTxId: DoubleSha256DigestBE,
+      outputIdx: Int,
+      tempContractId: Sha256Digest): ByteVector = {
+    val u16 = UInt16(outputIdx)
+    //we need to pad the u16 due to how xor works in scodec so we don't lose precision
+    val padded = ByteVector.fill(30)(0.toByte) ++ u16.bytes
+    fundingTxId.bytes
+      .xor(tempContractId.bytes)
+      .xor(padded)
+  }
+
   /** @see https://github.com/discreetlogcontracts/dlcspecs/blob/master/Protocol.md#definition-of-contract_id
     * @param fundingTx the transaction that contains the DLC funding output
     * @param outputIdx the index of the output
@@ -37,12 +55,7 @@ object DLCUtil {
       fundingTx: Transaction,
       outputIdx: Int,
       tempContractId: Sha256Digest): ByteVector = {
-    val u16 = UInt16(outputIdx)
-    //we need to pad the u16 due to how xor works in scodec so we don't lose precision
-    val padded = ByteVector.fill(30)(0.toByte) ++ u16.bytes
-    fundingTx.txIdBE.bytes
-      .xor(tempContractId.bytes)
-      .xor(padded)
+    computeContractId(fundingTx.txIdBE, outputIdx, tempContractId)
   }
 
   /** Extracts an adaptor secret from cetSig assuming it is the completion
diff --git a/wallet-test/src/test/resources/contract_id_test.json b/wallet-test/src/test/resources/contract_id_test.json
new file mode 100644
index 0000000000..972ea2c5db
--- /dev/null
+++ b/wallet-test/src/test/resources/contract_id_test.json
@@ -0,0 +1,26 @@
+[
+  {
+    "fundTxId": "22141d1118d666016f384cff3bf7fa124fe9ff0dcc206de88226219be5c6ee04",
+    "fundOutputIndex": 2,
+    "temporaryContractId": "925b5cbfdd7742d9e9ae0a6c869ce58ec56843ab539dd125a34a19661f3dabe9",
+    "contractId": "b04f41aec5a124d886964693bd6b1f9c8a81bca69fbdbccd216c38fdfafb45ef"
+  },
+  {
+    "fundTxId": "67f25e18f0aca45196836508f5b3149fc900bd1709b32cf8f4d9f390744ba0b2",
+    "fundOutputIndex": 0,
+    "temporaryContractId": "83b848da05afbb4aa984731742ace0217cbc1a2bed72abfcdbd3059e171e78b4",
+    "contractId": "e44a16c2f5031f1b3f07161fb71ff4beb5bca73ce4c187042f0af60e6355d806"
+  },
+  {
+    "fundTxId": "f10dc6857bb7562ef1920a5401c8332ac22adf12df695739b6afd5ed0ae2ee9b",
+    "fundOutputIndex": 2,
+    "temporaryContractId": "942bcce00a0a6ca1b41381e290fdcd68474ba6527131b81eeb2a143414fa4f4c",
+    "contractId": "65260a6571bd3a8f45818bb69135fe4285617940ae58ef275d85c1d91e18a1d5"
+  },
+  {
+    "fundTxId": "75511322ccf0422f723ebc359bdde79f46134b046544bbfdd945dc1848cbc5c4",
+    "fundOutputIndex": 1,
+    "temporaryContractId": "c690e64ac286fc379c4b1f6fb69fb17626e589f50b6d6c2efc93ce8f299142b9",
+    "contractId": "b3c1f5680e76be18ee75a35a2d4256e960f6c2f16e29d7d325d61297615a877c"
+  }
+]
\ No newline at end of file
diff --git a/wallet-test/src/test/scala/org/bitcoins/wallet/ComputeContractIdTest.scala b/wallet-test/src/test/scala/org/bitcoins/wallet/ComputeContractIdTest.scala
new file mode 100644
index 0000000000..1ae833f6ca
--- /dev/null
+++ b/wallet-test/src/test/scala/org/bitcoins/wallet/ComputeContractIdTest.scala
@@ -0,0 +1,56 @@
+package org.bitcoins.wallet
+
+import org.bitcoins.commons.serializers.JsonReaders.byteVectorReads
+import org.bitcoins.commons.serializers.JsonSerializers._
+import org.bitcoins.core.protocol.dlc.compute.DLCUtil
+import org.bitcoins.crypto.{DoubleSha256DigestBE, Sha256Digest}
+import org.bitcoins.testkit.fixtures.EmptyFixture
+import org.bitcoins.testkit.wallet.BitcoinSWalletTest
+import play.api.libs.json._
+import scodec.bits.ByteVector
+import scala.io.Source
+
+class ComputeContractIdTest extends BitcoinSWalletTest with EmptyFixture {
+
+  lazy val json: JsValue = {
+    val stream = {
+      val classLoader = getClass().getClassLoader()
+      classLoader.getResourceAsStream("contract_id_test.json")
+    }
+    val rawText = Source
+      .fromInputStream(stream)
+      .getLines()
+      .mkString
+    Json.parse(rawText)
+  }
+
+  case class ContractIdTestVector(
+      fundTxId: DoubleSha256DigestBE,
+      fundOutputIndex: Int,
+      temporaryContractId: Sha256Digest,
+      contractId: ByteVector)
+
+  object ContractIdTestVector {
+
+    implicit val reads: Reads[ContractIdTestVector] =
+      Json.reads[ContractIdTestVector]
+  }
+
+  lazy val vectors: Vector[ContractIdTestVector] =
+    json.validate[Vector[ContractIdTestVector]] match {
+      case JsError(errors)     => fail(errors.head.toString)
+      case JsSuccess(value, _) => value
+    }
+
+  "DLCUtil" must "compute contract ids correctly as in the JSON file" in { _ =>
+    vectors.foreach { testVector =>
+      assert(
+        DLCUtil.computeContractId(
+          testVector.fundTxId,
+          testVector.fundOutputIndex,
+          testVector.temporaryContractId) == testVector.contractId)
+    }
+
+    succeed
+  }
+}