From e4e4e45a475b81ef624140c01c3f8ca6fa94d2f6 Mon Sep 17 00:00:00 2001
From: Mike Hearn <hearn@google.com>
Date: Sat, 12 Jan 2013 14:47:43 +0100
Subject: [PATCH] Allow re-signing of transactions and re-sign after adjusting
 the sequence number.

---
 core/src/main/java/com/google/bitcoin/core/Transaction.java  | 4 ++--
 tools/src/main/java/com/google/bitcoin/tools/WalletTool.java | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/core/src/main/java/com/google/bitcoin/core/Transaction.java b/core/src/main/java/com/google/bitcoin/core/Transaction.java
index eaacd5b0..58c57180 100644
--- a/core/src/main/java/com/google/bitcoin/core/Transaction.java
+++ b/core/src/main/java/com/google/bitcoin/core/Transaction.java
@@ -709,7 +709,8 @@ public class Transaction extends ChildMessage implements Serializable {
         ECKey[] signingKeys = new ECKey[inputs.size()];
         for (int i = 0; i < inputs.size(); i++) {
             TransactionInput input = inputs.get(i);
-            Preconditions.checkState(input.getScriptBytes().length == 0, "Attempting to sign a non-fresh transaction");
+            if (input.getScriptBytes().length != 0)
+                log.warn("Re-signing an already signed transaction! Be sure this is what you want.");
             // Find the signing key we'll need to use.
             ECKey key = input.getOutpoint().getConnectedKey(wallet);
             // This assert should never fire. If it does, it means the wallet is inconsistent.
@@ -743,7 +744,6 @@ public class Transaction extends ChildMessage implements Serializable {
         // 2) For pay-to-key outputs: just a signature.
         for (int i = 0; i < inputs.size(); i++) {
             TransactionInput input = inputs.get(i);
-            Preconditions.checkState(input.getScriptBytes().length == 0);
             ECKey key = signingKeys[i];
             Script scriptPubKey = input.getOutpoint().getConnectedOutput().getScriptPubKey();
             if (scriptPubKey.isSentToAddress()) {
diff --git a/tools/src/main/java/com/google/bitcoin/tools/WalletTool.java b/tools/src/main/java/com/google/bitcoin/tools/WalletTool.java
index 94e59dc9..d9d67329 100644
--- a/tools/src/main/java/com/google/bitcoin/tools/WalletTool.java
+++ b/tools/src/main/java/com/google/bitcoin/tools/WalletTool.java
@@ -424,10 +424,14 @@ public class WalletTool {
                     t.setLockTime(Transaction.parseLockTimeStr(lockTimeStr));
                     // For lock times to take effect, at least one output must have a non-final sequence number.
                     t.getInputs().get(0).setSequenceNumber(0);
+                    // And because we modified the transaction after it was completed, we must re-sign the inputs.
+                    t.signInputs(Transaction.SigHash.ALL, wallet);
                 }
             } catch (ParseException e) {
                 System.err.println("Could not understand --locktime of " + lockTimeStr);
                 return;
+            } catch (ScriptException e) {
+                throw new RuntimeException(e);
             }
             t = req.tx;   // Not strictly required today.
             setup();