From 245815b4d4708367eb1b7edb4c9cb594a30a4ade Mon Sep 17 00:00:00 2001
From: Chris Stewart <stewart.chris1234@gmail.com>
Date: Fri, 6 May 2016 16:41:59 -0500
Subject: [PATCH] Fixing bug with signature serialization - if we have more
 inputs than outputs & we are using SIGHASH_SINGLE the errorHash is signed

---
 .../TransactionSignatureSerializer.scala      | 22 ++++++++++++++++---
 .../transaction/TransactionTest.scala         |  6 ++---
 .../CoreTransactionTestCase.scala             |  1 +
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/src/main/scala/org/bitcoins/crypto/TransactionSignatureSerializer.scala b/src/main/scala/org/bitcoins/crypto/TransactionSignatureSerializer.scala
index 74950323e7..62754a94bc 100644
--- a/src/main/scala/org/bitcoins/crypto/TransactionSignatureSerializer.scala
+++ b/src/main/scala/org/bitcoins/crypto/TransactionSignatureSerializer.scala
@@ -47,6 +47,11 @@ trait TransactionSignatureSerializer extends RawBitcoinSerializerHelper with Bit
    * @return
    */
   def serializeForSignature(spendingTransaction : Transaction, inputIndex : Int, script : ScriptPubKey, hashType : HashType) : Seq[Byte] = {
+    logger.debug("Serializing for signature")
+
+
+
+
     // Clear input scripts in preparation for signing. If we're signing a fresh
     // transaction that step isn't very helpful, but it doesn't add much cost relative to the actual
     // EC math so we'll do it anyway.
@@ -147,9 +152,20 @@ trait TransactionSignatureSerializer extends RawBitcoinSerializerHelper with Bit
    * @param hashType
    * @return
    */
-  def hashForSignature(spendingTransction : Transaction, inputIndex : Int, script : ScriptPubKey, hashType : HashType) : Seq[Byte] = {
-    val serializedTxForSignature = serializeForSignature(spendingTransction,inputIndex,script,hashType)
-    CryptoUtil.doubleSHA256(serializedTxForSignature)
+  def hashForSignature(spendingTransaction : Transaction, inputIndex : Int, script : ScriptPubKey, hashType : HashType) : Seq[Byte] = {
+    //these first two checks are in accordance with behavior in bitcoin core
+    //https://github.com/bitcoin/bitcoin/blob/master/src/script/interpreter.cpp#L1112-L1123
+    if (inputIndex >= spendingTransaction.inputs.size ) {
+      logger.warn("Our inputIndex is out of the range of the inputs in the spending transaction")
+      errorHash
+    }
+    else if(hashType == SIGHASH_SINGLE  && inputIndex >= spendingTransaction.outputs.size) {
+      logger.warn("When we have a SIGHASH_SINGLE we cannot have more inputs than outputs")
+      errorHash
+    } else {
+      val serializedTxForSignature = serializeForSignature(spendingTransaction,inputIndex,script,hashType)
+      CryptoUtil.doubleSHA256(serializedTxForSignature)
+    }
   }
 
   /**
diff --git a/src/test/scala/org/bitcoins/protocol/transaction/TransactionTest.scala b/src/test/scala/org/bitcoins/protocol/transaction/TransactionTest.scala
index 4e2159f23a..148cc1853a 100644
--- a/src/test/scala/org/bitcoins/protocol/transaction/TransactionTest.scala
+++ b/src/test/scala/org/bitcoins/protocol/transaction/TransactionTest.scala
@@ -49,14 +49,14 @@ class TransactionTest extends FlatSpec with MustMatchers with BitcoinSLogger {
 
 
         //use this to represent a single test case from script_valid.json
-/*    val lines =
+    val lines =
         """
           |[
           |[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "DUP HASH160 0x14 0xe52b482f2faa8ecbf0db344f93c84ac908557f33 EQUALVERIFY CHECKSIG"], ["0000000000000000000000000000000000000000000000000000000000000200", 0, "1"]],
           |"01000000020002000000000000000000000000000000000000000000000000000000000000000000000151ffffffff0001000000000000000000000000000000000000000000000000000000000000000000006b483045022100c9cdd08798a28af9d1baf44a6c77bcc7e279f47dc487c8c899911bc48feaffcc0220503c5c50ae3998a733263c5c0f7061b483e2b56c4c41b456e7d2f5a78a74c077032102d5c25adb51b61339d2b05315791e21bbe80ea470a49db0135720983c905aace0ffffffff010000000000000000015100000000", "P2SH"]
           |]
-        """.stripMargin*/
-    val lines = try source.getLines.filterNot(_.isEmpty).map(_.trim) mkString "\n" finally source.close()
+        """.stripMargin
+    //val lines = try source.getLines.filterNot(_.isEmpty).map(_.trim) mkString "\n" finally source.close()
     val json = lines.parseJson
     val testCasesOpt : Seq[Option[CoreTransactionTestCase]] = json.convertTo[Seq[Option[CoreTransactionTestCase]]]
     val testCases : Seq[CoreTransactionTestCase] = testCasesOpt.flatten
diff --git a/src/test/scala/org/bitcoins/protocol/transaction/testprotocol/CoreTransactionTestCase.scala b/src/test/scala/org/bitcoins/protocol/transaction/testprotocol/CoreTransactionTestCase.scala
index e9e82ee02c..fc26b59c1d 100644
--- a/src/test/scala/org/bitcoins/protocol/transaction/testprotocol/CoreTransactionTestCase.scala
+++ b/src/test/scala/org/bitcoins/protocol/transaction/testprotocol/CoreTransactionTestCase.scala
@@ -17,6 +17,7 @@ trait CoreTransactionTestCase {
   def scriptPubKeys : Seq[ScriptPubKey] = creditingTxsInfo.map(_._2)
 
   def creditingTxsInfo : Seq[(TransactionOutPoint, ScriptPubKey)]
+
   def spendingTx : Transaction
 
   def flags : Seq[ScriptFlag]