From b0739df2e548b3c1abe9f68da0323a6f137445e8 Mon Sep 17 00:00:00 2001
From: Mike Hearn <hearn@google.com>
Date: Thu, 2 Feb 2012 18:21:28 +0100
Subject: [PATCH] Expose hashTransactionForSignature. The API will likely
 change in future.

---
 src/com/google/bitcoin/core/Transaction.java | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/com/google/bitcoin/core/Transaction.java b/src/com/google/bitcoin/core/Transaction.java
index eab82a2d..32e2324a 100644
--- a/src/com/google/bitcoin/core/Transaction.java
+++ b/src/com/google/bitcoin/core/Transaction.java
@@ -628,7 +628,17 @@ public class Transaction extends ChildMessage implements Serializable {
         // Every input is now complete.
     }
 
-    private byte[] hashTransactionForSignature(SigHash type, boolean anyoneCanPay) {
+    /**
+     * Calculates a signature hash, that is, a hash of a simplified form of the transaction. How exactly the transaction
+     * is simplified is specified by the type and anyoneCanPay parameters.<p>
+     *
+     * You don't normally ever need to call this yourself. It will become more useful in future as the contracts
+     * features of Bitcoin are developed.
+     *
+     * @param type Should be SigHash.ALL
+     * @param anyoneCanPay should be false.
+     */
+    public byte[] hashTransactionForSignature(SigHash type, boolean anyoneCanPay) {
         try {
             ByteArrayOutputStream bos = new UnsafeByteArrayOutputStream(length == UNKNOWN_LENGTH ? 256 : length + 4);
             bitcoinSerialize(bos);