Support CLTV micropayment channels

Also extend WalletTool to send via, settle and refund these channels.

core/src/main/java/org/bitcoinj/core/Wallet.java

@@ -33,7 +33,6 @@ import org.bitcoinj.core.listeners.WalletChangeEventListener;
 import org.bitcoinj.core.listeners.WalletCoinEventListener;
 import org.bitcoinj.core.TransactionConfidence.*;
 import org.bitcoinj.crypto.*;
-import org.bitcoinj.params.*;
 import org.bitcoinj.script.*;
 import org.bitcoinj.signers.*;
 import org.bitcoinj.store.*;
@@ -3643,6 +3642,24 @@ public class Wallet extends BaseTaggableObject
             return req;
         }
 
+        public static SendRequest toCLTVPaymentChannel(NetworkParameters params, Date releaseTime, ECKey from, ECKey to, Coin value) {
+            long time = releaseTime.getTime() / 1000L;
+            checkArgument(time >= Transaction.LOCKTIME_THRESHOLD, "Release time was too small");
+            return toCLTVPaymentChannel(params, BigInteger.valueOf(time), from, to, value);
+        }
+
+        public static SendRequest toCLTVPaymentChannel(NetworkParameters params, long lockTime, ECKey from, ECKey to, Coin value) {
+            return toCLTVPaymentChannel(params, BigInteger.valueOf(lockTime), from, to, value);
+        }
+
+        private static SendRequest toCLTVPaymentChannel(NetworkParameters params, BigInteger time, ECKey from, ECKey to, Coin value) {
+            SendRequest req = new SendRequest();
+            Script output = ScriptBuilder.createCLTVPaymentChannelOutput(time, from, to);
+            req.tx = new Transaction(params);
+            req.tx.addOutput(value, output);
+            return req;
+        }
+
         /** Copy data from payment request. */
         public SendRequest fromPaymentDetails(PaymentDetails paymentDetails) {
             if (paymentDetails.hasMemo())
@@ -4120,6 +4137,19 @@ public class Wallet extends BaseTaggableObject
                 if (key != null && (key.isEncrypted() || key.hasPrivKey()))
                     return true;
             }
+        } else if (script.isSentToCLTVPaymentChannel()) {
+            // Any script for which we are the recipient or sender counts.
+            byte[] sender = script.getCLTVPaymentChannelSenderPubKey();
+            ECKey senderKey = findKeyFromPubKey(sender);
+            if (senderKey != null && (senderKey.isEncrypted() || senderKey.hasPrivKey())) {
+                return true;
+            }
+            byte[] recipient = script.getCLTVPaymentChannelRecipientPubKey();
+            ECKey recipientKey = findKeyFromPubKey(sender);
+            if (recipientKey != null && (recipientKey.isEncrypted() || recipientKey.hasPrivKey())) {
+                return true;
+            }
+            return false;
         }
         return false;
     }

core/src/main/java/org/bitcoinj/script/Script.java

@@ -302,6 +302,37 @@ public class Script {
         }
     }
 
+    /**
+     * Retrieves the sender public key from a LOCKTIMEVERIFY transaction
+     * @return
+     * @throws ScriptException
+     */
+    public byte[] getCLTVPaymentChannelSenderPubKey() throws ScriptException {
+        if (!isSentToCLTVPaymentChannel()) {
+            throw new ScriptException("Script not a standard CHECKLOCKTIMVERIFY transaction: " + this);
+        }
+        return chunks.get(8).data;
+    }
+
+    /**
+     * Retrieves the recipient public key from a LOCKTIMEVERIFY transaction
+     * @return
+     * @throws ScriptException
+     */
+    public byte[] getCLTVPaymentChannelRecipientPubKey() throws ScriptException {
+        if (!isSentToCLTVPaymentChannel()) {
+            throw new ScriptException("Script not a standard CHECKLOCKTIMVERIFY transaction: " + this);
+        }
+        return chunks.get(1).data;
+    }
+
+    public BigInteger getCLTVPaymentChannelExpiry() {
+        if (!isSentToCLTVPaymentChannel()) {
+            throw new ScriptException("Script not a standard CHECKLOCKTIMEVERIFY transaction: " + this);
+        }
+        return castToBigInteger(chunks.get(4).data, 5);
+    }
+
     /**
      * For 2-element [input] scripts assumes that the paid-to-address can be derived from the public key.
      * The concept of a "from address" isn't well defined in Bitcoin and you should not assume the sender of a
@@ -686,6 +717,22 @@ public class Script {
         return true;
     }
 
+    public boolean isSentToCLTVPaymentChannel() {
+        if (chunks.size() != 10) return false;
+        // Check that opcodes match the pre-determined format.
+        if (!chunks.get(0).equalsOpCode(OP_IF)) return false;
+        // chunk[1] = recipient pubkey
+        if (!chunks.get(2).equalsOpCode(OP_CHECKSIGVERIFY)) return false;
+        if (!chunks.get(3).equalsOpCode(OP_ELSE)) return false;
+        // chunk[4] = locktime
+        if (!chunks.get(5).equalsOpCode(OP_CHECKLOCKTIMEVERIFY)) return false;
+        if (!chunks.get(6).equalsOpCode(OP_DROP)) return false;
+        if (!chunks.get(7).equalsOpCode(OP_ENDIF)) return false;
+        // chunk[8] = sender pubkey
+        if (!chunks.get(9).equalsOpCode(OP_CHECKSIG)) return false;
+        return true;
+    }
+
     private static boolean equalsRange(byte[] a, int start, byte[] b) {
         if (start + b.length > a.length)
             return false;

core/src/main/java/org/bitcoinj/script/ScriptBuilder.java

@@ -23,6 +23,7 @@ import org.bitcoinj.core.Utils;
 import org.bitcoinj.crypto.TransactionSignature;
 
 import javax.annotation.Nullable;
+import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -435,4 +436,32 @@ public class ScriptBuilder {
         checkArgument(data.length <= 40);
         return new ScriptBuilder().op(OP_RETURN).data(data).build();
     }
+
+    public static Script createCLTVPaymentChannelOutput(BigInteger time, ECKey from, ECKey to) {
+        byte[] timeBytes = Utils.reverseBytes(Utils.encodeMPI(time, false));
+        if (timeBytes.length > 5) {
+            throw new RuntimeException("Time too large to encode as 5-byte int");
+        }
+        return new ScriptBuilder().op(OP_IF)
+                .data(to.getPubKey()).op(OP_CHECKSIGVERIFY)
+                .op(OP_ELSE)
+                .data(timeBytes).op(OP_CHECKLOCKTIMEVERIFY).op(OP_DROP)
+                .op(OP_ENDIF)
+                .data(from.getPubKey()).op(OP_CHECKSIG).build();
+    }
+
+    public static Script createCLTVPaymentChannelRefund(TransactionSignature signature) {
+        ScriptBuilder builder = new ScriptBuilder();
+        builder.data(signature.encodeToBitcoin());
+        builder.data(new byte[] { 0 }); // Use the CHECKLOCKTIMEVERIFY if branch
+        return builder.build();
+    }
+
+    public static Script createCLTVPaymentChannelInput(TransactionSignature from, TransactionSignature to) {
+        ScriptBuilder builder = new ScriptBuilder();
+        builder.data(from.encodeToBitcoin());
+        builder.data(to.encodeToBitcoin());
+        builder.smallNum(1); // Use the CHECKLOCKTIMEVERIFY if branch
+        return builder.build();
+    }
 }

core/src/test/java/org/bitcoinj/core/TransactionTest.java

@@ -1,12 +1,14 @@
 package org.bitcoinj.core;
 
 import org.bitcoinj.core.TransactionConfidence.*;
+import org.bitcoinj.crypto.TransactionSignature;
 import org.bitcoinj.params.*;
 import org.bitcoinj.script.*;
 import org.bitcoinj.testing.*;
 import org.easymock.*;
 import org.junit.*;
 
+import java.math.BigInteger;
 import java.util.*;
 import static org.bitcoinj.core.BlockTest.params;
 import static org.bitcoinj.core.Utils.HEX;
@@ -205,6 +207,86 @@ public class TransactionTest {
         assertEquals(tx.isMature(), false);
     }
 
+    @Test
+    public void testCLTVPaymentChannelTransactionSpending() {
+        BigInteger time = BigInteger.valueOf(20);
+
+        ECKey from = new ECKey(), to = new ECKey(), incorrect = new ECKey();
+        Script outputScript = ScriptBuilder.createCLTVPaymentChannelOutput(time, from, to);
+
+        Transaction tx = new Transaction(PARAMS);
+        tx.addInput(new TransactionInput(PARAMS, tx, new byte[] {}));
+        tx.getInput(0).setSequenceNumber(0);
+        tx.setLockTime(time.subtract(BigInteger.ONE).longValue());
+        TransactionSignature fromSig =
+                tx.calculateSignature(0, from, outputScript, Transaction.SigHash.SINGLE, false);
+        TransactionSignature toSig =
+                tx.calculateSignature(0, to, outputScript, Transaction.SigHash.SINGLE, false);
+        TransactionSignature incorrectSig =
+                tx.calculateSignature(0, incorrect, outputScript, Transaction.SigHash.SINGLE, false);
+        Script scriptSig =
+                ScriptBuilder.createCLTVPaymentChannelInput(fromSig, toSig);
+        Script refundSig =
+                ScriptBuilder.createCLTVPaymentChannelRefund(fromSig);
+        Script invalidScriptSig1 =
+                ScriptBuilder.createCLTVPaymentChannelInput(fromSig, incorrectSig);
+        Script invalidScriptSig2 =
+                ScriptBuilder.createCLTVPaymentChannelInput(incorrectSig, toSig);
+
+        try {
+            scriptSig.correctlySpends(tx, 0, outputScript, Script.ALL_VERIFY_FLAGS);
+        } catch (ScriptException e) {
+            e.printStackTrace();
+            fail("Settle transaction failed to correctly spend the payment channel");
+        }
+
+        try {
+            refundSig.correctlySpends(tx, 0, outputScript, Script.ALL_VERIFY_FLAGS);
+            fail("Refund passed before expiry");
+        } catch (ScriptException e) { }
+        try {
+            invalidScriptSig1.correctlySpends(tx, 0, outputScript, Script.ALL_VERIFY_FLAGS);
+            fail("Invalid sig 1 passed");
+        } catch (ScriptException e) { }
+        try {
+            invalidScriptSig2.correctlySpends(tx, 0, outputScript, Script.ALL_VERIFY_FLAGS);
+            fail("Invalid sig 2 passed");
+        } catch (ScriptException e) { }
+    }
+
+    @Test
+    public void testCLTVPaymentChannelTransactionRefund() {
+        BigInteger time = BigInteger.valueOf(20);
+
+        ECKey from = new ECKey(), to = new ECKey(), incorrect = new ECKey();
+        Script outputScript = ScriptBuilder.createCLTVPaymentChannelOutput(time, from, to);
+
+        Transaction tx = new Transaction(PARAMS);
+        tx.addInput(new TransactionInput(PARAMS, tx, new byte[] {}));
+        tx.getInput(0).setSequenceNumber(0);
+        tx.setLockTime(time.add(BigInteger.ONE).longValue());
+        TransactionSignature fromSig =
+                tx.calculateSignature(0, from, outputScript, Transaction.SigHash.SINGLE, false);
+        TransactionSignature incorrectSig =
+                tx.calculateSignature(0, incorrect, outputScript, Transaction.SigHash.SINGLE, false);
+        Script scriptSig =
+                ScriptBuilder.createCLTVPaymentChannelRefund(fromSig);
+        Script invalidScriptSig =
+                ScriptBuilder.createCLTVPaymentChannelRefund(incorrectSig);
+
+        try {
+            scriptSig.correctlySpends(tx, 0, outputScript, Script.ALL_VERIFY_FLAGS);
+        } catch (ScriptException e) {
+            e.printStackTrace();
+            fail("Refund failed to correctly spend the payment channel");
+        }
+
+        try {
+            invalidScriptSig.correctlySpends(tx, 0, outputScript, Script.ALL_VERIFY_FLAGS);
+            fail("Invalid sig passed");
+        } catch (ScriptException e) { }
+    }
+
     @Test
     public void testToStringWhenLockTimeIsSpecifiedInBlockHeight() {
         Transaction tx = newTransaction();

core/src/test/java/org/bitcoinj/script/ScriptTest.java

@@ -406,6 +406,12 @@ public class ScriptTest {
         }
     }
 
+    @Test
+    public void testCLTVPaymentChannelOutput() {
+        Script script = ScriptBuilder.createCLTVPaymentChannelOutput(BigInteger.valueOf(20), new ECKey(), new ECKey());
+        assertTrue("script is locktime-verify", script.isSentToCLTVPaymentChannel());
+    }
+
     @Test
     public void getToAddress() throws Exception {
         // pay to pubkey

tools/src/main/java/org/bitcoinj/tools/WalletTool.java

@@ -19,10 +19,7 @@ package org.bitcoinj.tools;
 
 import org.bitcoinj.core.*;
 import org.bitcoinj.core.Wallet.BalanceType;
-import org.bitcoinj.crypto.DeterministicKey;
-import org.bitcoinj.crypto.KeyCrypterException;
-import org.bitcoinj.crypto.MnemonicCode;
-import org.bitcoinj.crypto.MnemonicException;
+import org.bitcoinj.crypto.*;
 import org.bitcoinj.net.discovery.DnsDiscovery;
 import org.bitcoinj.params.MainNetParams;
 import org.bitcoinj.params.RegTestParams;
@@ -30,6 +27,7 @@ import org.bitcoinj.params.TestNet3Params;
 import org.bitcoinj.protocols.payments.PaymentProtocol;
 import org.bitcoinj.protocols.payments.PaymentProtocolException;
 import org.bitcoinj.protocols.payments.PaymentSession;
+import org.bitcoinj.script.ScriptBuilder;
 import org.bitcoinj.store.*;
 import org.bitcoinj.uri.BitcoinURI;
 import org.bitcoinj.uri.BitcoinURIParseException;
@@ -173,6 +171,9 @@ public class WalletTool {
         SYNC,
         RESET,
         SEND,
+        SEND_CLTVPAYMENTCHANNEL,
+        SETTLE_CLTVPAYMENTCHANNEL,
+        REFUND_CLTVPAYMENTCHANNEL,
         ENCRYPT,
         DECRYPT,
         MARRY,
@@ -228,6 +229,8 @@ public class WalletTool {
         parser.accepts("no-pki");
         parser.accepts("tor");
         parser.accepts("dump-privkeys");
+        OptionSpec<String> refundFlag = parser.accepts("refund-to").withRequiredArg();
+        OptionSpec<String> txHashFlag = parser.accepts("txhash").withRequiredArg();
         options = parser.parse(args);
 
         if (args.length == 0 || options.has("help") ||
@@ -366,6 +369,59 @@ public class WalletTool {
                     return;
                 }
                 break;
+            case SEND_CLTVPAYMENTCHANNEL: {
+                if (!options.has(outputFlag)) {
+                    System.err.println("You must specify a --output=addr:value");
+                    return;
+                }
+                Coin fee = Coin.ZERO;
+                if (options.has("fee")) {
+                    fee = parseCoin((String) options.valueOf("fee"));
+                }
+                if (!options.has("locktime")) {
+                    System.err.println("You must specify a --locktime");
+                    return;
+                }
+                String lockTime = (String) options.valueOf("locktime");
+                boolean allowUnconfirmed = options.has("allow-unconfirmed");
+                if (!options.has(refundFlag)) {
+                    System.err.println("You must specify an address to refund money to after expiry: --refund-to=addr");
+                    return;
+                }
+                sendCLTVPaymentChannel(refundFlag.value(options), outputFlag.value(options), fee, lockTime, allowUnconfirmed);
+                } break;
+            case SETTLE_CLTVPAYMENTCHANNEL: {
+                if (!options.has(outputFlag)) {
+                    System.err.println("You must specify a --output=addr:value");
+                    return;
+                }
+                Coin fee = Coin.ZERO;
+                if (options.has("fee")) {
+                    fee = parseCoin((String) options.valueOf("fee"));
+                }
+                boolean allowUnconfirmed = options.has("allow-unconfirmed");
+                if (!options.has(txHashFlag)) {
+                    System.err.println("You must specify the transaction to spend: --txhash=tx-hash");
+                    return;
+                }
+                settleCLTVPaymentChannel(txHashFlag.value(options), outputFlag.value(options), fee, allowUnconfirmed);
+                } break;
+            case REFUND_CLTVPAYMENTCHANNEL: {
+                if (!options.has(outputFlag)) {
+                    System.err.println("You must specify a --output=addr:value");
+                    return;
+                }
+                Coin fee = Coin.ZERO;
+                if (options.has("fee")) {
+                    fee = parseCoin((String) options.valueOf("fee"));
+                }
+                boolean allowUnconfirmed = options.has("allow-unconfirmed");
+                if (!options.has(txHashFlag)) {
+                    System.err.println("You must specify the transaction to spend: --txhash=tx-hash");
+                    return;
+                }
+                refundCLTVPaymentChannel(txHashFlag.value(options), outputFlag.value(options), fee, allowUnconfirmed);
+            } break;
             case ENCRYPT: encrypt(); break;
             case DECRYPT: decrypt(); break;
             case MARRY: marry(); break;
@@ -513,36 +569,25 @@ public class WalletTool {
             // Convert the input strings to outputs.
             Transaction t = new Transaction(params);
             for (String spec : outputs) {
-                String[] parts = spec.split(":");
-                if (parts.length != 2) {
-                    System.err.println("Malformed output specification, must have two parts separated by :");
-                    return;
-                }
-                String destination = parts[0];
                 try {
-                    Coin value;
-                    if ("ALL".equalsIgnoreCase(parts[1]))
-                        value = wallet.getBalance(BalanceType.ESTIMATED);
-                    else
-                        value = parseCoin(parts[1]);
-                    if (destination.startsWith("0")) {
-                        // Treat as a raw public key.
-                        byte[] pubKey = new BigInteger(destination, 16).toByteArray();
-                        ECKey key = ECKey.fromPublicOnly(pubKey);
-                        t.addOutput(value, key);
+                    OutputSpec outputSpec = new OutputSpec(spec);
+                    if (outputSpec.isAddress()) {
+                        t.addOutput(outputSpec.value, outputSpec.addr);
                     } else {
-                        // Treat as an address.
-                        Address addr = Address.fromBase58(params, destination);
-                        t.addOutput(value, addr);
+                        t.addOutput(outputSpec.value, outputSpec.key);
                     }
                 } catch (WrongNetworkException e) {
-                    System.err.println("Malformed output specification, address is for a different network: " + parts[0]);
+                    System.err.println("Malformed output specification, address is for a different network: " + spec);
                     return;
                 } catch (AddressFormatException e) {
-                    System.err.println("Malformed output specification, could not parse as address: " + parts[0]);
+                    System.err.println("Malformed output specification, could not parse as address: " + spec);
                     return;
                 } catch (NumberFormatException e) {
-                    System.err.println("Malformed output specification, could not parse as value: " + parts[1]);
+                    System.err.println("Malformed output specification, could not parse as value: " + spec);
+                    return;
+                } catch (IllegalArgumentException e) {
+                    System.err.println(e.getMessage());
+                    return;
                 }
             }
             Wallet.SendRequest req = Wallet.SendRequest.forTx(t);
@@ -605,6 +650,335 @@ public class WalletTool {
         }
     }
 
+    static class OutputSpec {
+        public final Coin value;
+        public final Address addr;
+        public final ECKey key;
+
+        public OutputSpec(String spec) throws IllegalArgumentException {
+            String[] parts = spec.split(":");
+            if (parts.length != 2) {
+                throw new IllegalArgumentException("Malformed output specification, must have two parts separated by :");
+            }
+            String destination = parts[0];
+            if ("ALL".equalsIgnoreCase(parts[1]))
+                value = wallet.getBalance(BalanceType.ESTIMATED);
+            else
+                value = parseCoin(parts[1]);
+            if (destination.startsWith("0")) {
+                // Treat as a raw public key.
+                byte[] pubKey = new BigInteger(destination, 16).toByteArray();
+                key = ECKey.fromPublicOnly(pubKey);
+                addr = null;
+            } else {
+                // Treat as an address.
+                addr = Address.fromBase58(params, destination);
+                key = null;
+            }
+        }
+
+        public boolean isAddress() {
+            return addr != null;
+        }
+    }
+
+    private static void sendCLTVPaymentChannel(String refund, String output, Coin fee, String lockTimeStr, boolean allowUnconfirmed) throws VerificationException {
+        try {
+            // Convert the input strings to outputs.
+            ECKey outputKey, refundKey;
+            Coin value;
+            try {
+                OutputSpec outputSpec = new OutputSpec(output);
+                if (outputSpec.isAddress()) {
+                    System.err.println("Output specification must be a public key");
+                    return;
+                }
+                outputKey = outputSpec.key;
+                value = outputSpec.value;
+                byte[] refundPubKey = new BigInteger(refund, 16).toByteArray();
+                refundKey = ECKey.fromPublicOnly(refundPubKey);
+            } catch (WrongNetworkException e) {
+                System.err.println("Malformed output specification, address is for a different network.");
+                return;
+            } catch (AddressFormatException e) {
+                System.err.println("Malformed output specification, could not parse as address.");
+                return;
+            } catch (NumberFormatException e) {
+                System.err.println("Malformed output specification, could not parse as value.");
+                return;
+            } catch (IllegalArgumentException e) {
+                System.err.println(e.getMessage());
+                return;
+            }
+
+            long lockTime;
+            try {
+                lockTime = parseLockTimeStr(lockTimeStr);
+            } catch (ParseException e) {
+                System.err.println("Could not understand --locktime of " + lockTimeStr);
+                return;
+            } catch (ScriptException e) {
+                throw new RuntimeException(e);
+            }
+
+            Wallet.SendRequest req = Wallet.SendRequest.toCLTVPaymentChannel(params, lockTime, refundKey, outputKey, value);
+            if (req.tx.getOutputs().size() == 1 && req.tx.getOutput(0).getValue().equals(wallet.getBalance())) {
+                log.info("Emptying out wallet, recipient may get less than what you expect");
+                req.emptyWallet = true;
+            }
+            req.fee = fee;
+            if (allowUnconfirmed) {
+                wallet.allowSpendingUnconfirmedTransactions();
+            }
+            if (password != null) {
+                req.aesKey = passwordToKey(true);
+                if (req.aesKey == null)
+                    return;  // Error message already printed.
+            }
+            wallet.completeTx(req);
+
+            System.out.println(req.tx.getHashAsString());
+            if (options.has("offline")) {
+                wallet.commitTx(req.tx);
+                return;
+            }
+
+            setup();
+            peers.start();
+            // Wait for peers to connect, the tx to be sent to one of them and for it to be propagated across the
+            // network. Once propagation is complete and we heard the transaction back from all our peers, it will
+            // be committed to the wallet.
+            peers.broadcastTransaction(req.tx).future().get();
+            // Hack for regtest/single peer mode, as we're about to shut down and won't get an ACK from the remote end.
+            List<Peer> peerList = peers.getConnectedPeers();
+            if (peerList.size() == 1)
+                peerList.get(0).ping().get();
+        } catch (BlockStoreException e) {
+            throw new RuntimeException(e);
+        } catch (KeyCrypterException e) {
+            throw new RuntimeException(e);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        } catch (ExecutionException e) {
+            throw new RuntimeException(e);
+        } catch (InsufficientMoneyException e) {
+            System.err.println("Insufficient funds: have " + wallet.getBalance().toFriendlyString());
+        }
+    }
+
+    /**
+     * Settles a CLTV payment channel transaction given that we own both private keys (ie. for testing).
+     * @param txHash
+     * @param output
+     * @param fee
+     * @param allowUnconfirmed
+     */
+    private static void settleCLTVPaymentChannel(String txHash, String output, Coin fee, boolean allowUnconfirmed) {
+        try {
+            OutputSpec outputSpec;
+            Coin value;
+            try {
+                outputSpec = new OutputSpec(output);
+                value = outputSpec.value;
+            } catch (WrongNetworkException e) {
+                System.err.println("Malformed output specification, address is for a different network.");
+                return;
+            } catch (AddressFormatException e) {
+                System.err.println("Malformed output specification, could not parse as address.");
+                return;
+            } catch (NumberFormatException e) {
+                System.err.println("Malformed output specification, could not parse as value.");
+                return;
+            } catch (IllegalArgumentException e) {
+                System.err.println(e.getMessage());
+                return;
+            }
+
+            Wallet.SendRequest req = outputSpec.isAddress() ?
+                    Wallet.SendRequest.to(outputSpec.addr, value) :
+                    Wallet.SendRequest.to(params, outputSpec.key, value);
+            req.fee = fee;
+
+            Transaction lockTimeVerify = wallet.getTransaction(Sha256Hash.wrap(txHash));
+            if (lockTimeVerify == null) {
+                System.err.println("Couldn't find transaction with given hash");
+                return;
+            }
+            TransactionOutput lockTimeVerifyOutput = null;
+            for (TransactionOutput out : lockTimeVerify.getOutputs()) {
+                if (out.getScriptPubKey().isSentToCLTVPaymentChannel()) {
+                    lockTimeVerifyOutput = out;
+                }
+            }
+            if (lockTimeVerifyOutput == null) {
+                System.err.println("TX to spend wasn't sent to LockTimeVerify");
+                return;
+            }
+
+            if (!req.fee.add(value).equals(lockTimeVerifyOutput.getValue())) {
+                System.err.println("You must spend all the money in the input transaction");
+            }
+
+            if (allowUnconfirmed) {
+                wallet.allowSpendingUnconfirmedTransactions();
+            }
+            if (password != null) {
+                req.aesKey = passwordToKey(true);
+                if (req.aesKey == null)
+                    return;  // Error message already printed.
+            }
+
+            ECKey key1 = wallet.findKeyFromPubKey(
+                    lockTimeVerifyOutput.getScriptPubKey().getCLTVPaymentChannelSenderPubKey());
+            ECKey key2 = wallet.findKeyFromPubKey(
+                    lockTimeVerifyOutput.getScriptPubKey().getCLTVPaymentChannelRecipientPubKey());
+            if (key1 == null || key2 == null) {
+                System.err.println("Don't own private keys for both pubkeys");
+                return;
+            }
+
+            TransactionInput input = new TransactionInput(
+                    params, req.tx, new byte[] {}, lockTimeVerifyOutput.getOutPointFor());
+            req.tx.addInput(input);
+            TransactionSignature sig1 =
+                    req.tx.calculateSignature(0, key1, lockTimeVerifyOutput.getScriptPubKey(), Transaction.SigHash.SINGLE, false);
+            TransactionSignature sig2 =
+                    req.tx.calculateSignature(0, key2, lockTimeVerifyOutput.getScriptPubKey(), Transaction.SigHash.SINGLE, false);
+            input.setScriptSig(ScriptBuilder.createCLTVPaymentChannelInput(sig1, sig2));
+
+            System.out.println(req.tx.getHashAsString());
+            if (options.has("offline")) {
+                wallet.commitTx(req.tx);
+                return;
+            }
+
+            setup();
+            peers.start();
+            // Wait for peers to connect, the tx to be sent to one of them and for it to be propagated across the
+            // network. Once propagation is complete and we heard the transaction back from all our peers, it will
+            // be committed to the wallet.
+            peers.broadcastTransaction(req.tx).future().get();
+            // Hack for regtest/single peer mode, as we're about to shut down and won't get an ACK from the remote end.
+            List<Peer> peerList = peers.getConnectedPeers();
+            if (peerList.size() == 1)
+                peerList.get(0).ping().get();
+        } catch (BlockStoreException e) {
+            throw new RuntimeException(e);
+        } catch (KeyCrypterException e) {
+            throw new RuntimeException(e);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        } catch (ExecutionException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Refunds a CLTV payment channel transaction after the lock time has expired.
+     * @param txHash
+     * @param output
+     * @param fee
+     * @param allowUnconfirmed
+     */
+    private static void refundCLTVPaymentChannel(String txHash, String output, Coin fee, boolean allowUnconfirmed) {
+        try {
+            OutputSpec outputSpec;
+            Coin value;
+            try {
+                outputSpec = new OutputSpec(output);
+                value = outputSpec.value;
+            } catch (WrongNetworkException e) {
+                System.err.println("Malformed output specification, address is for a different network.");
+                return;
+            } catch (AddressFormatException e) {
+                System.err.println("Malformed output specification, could not parse as address.");
+                return;
+            } catch (NumberFormatException e) {
+                System.err.println("Malformed output specification, could not parse as value.");
+                return;
+            } catch (IllegalArgumentException e) {
+                System.err.println(e.getMessage());
+                return;
+            }
+
+            Wallet.SendRequest req = outputSpec.isAddress() ?
+                    Wallet.SendRequest.to(outputSpec.addr, value) :
+                    Wallet.SendRequest.to(params, outputSpec.key, value);
+            req.fee = fee;
+
+            Transaction lockTimeVerify = wallet.getTransaction(Sha256Hash.wrap(txHash));
+            if (lockTimeVerify == null) {
+                System.err.println("Couldn't find transaction with given hash");
+                return;
+            }
+            TransactionOutput lockTimeVerifyOutput = null;
+            for (TransactionOutput out : lockTimeVerify.getOutputs()) {
+                if (out.getScriptPubKey().isSentToCLTVPaymentChannel()) {
+                    lockTimeVerifyOutput = out;
+                }
+            }
+            if (lockTimeVerifyOutput == null) {
+                System.err.println("TX to spend wasn't sent to LockTimeVerify");
+                return;
+            }
+
+            req.tx.setLockTime(lockTimeVerifyOutput.getScriptPubKey().getCLTVPaymentChannelExpiry().longValue());
+
+            if (!req.fee.add(value).equals(lockTimeVerifyOutput.getValue())) {
+                System.err.println("You must spend all the money in the input transaction");
+            }
+
+            if (allowUnconfirmed) {
+                wallet.allowSpendingUnconfirmedTransactions();
+            }
+            if (password != null) {
+                req.aesKey = passwordToKey(true);
+                if (req.aesKey == null)
+                    return;  // Error message already printed.
+            }
+
+            ECKey key = wallet.findKeyFromPubKey(
+                    lockTimeVerifyOutput.getScriptPubKey().getCLTVPaymentChannelSenderPubKey());
+            if (key == null) {
+                System.err.println("Don't own private key for pubkey");
+                return;
+            }
+
+            TransactionInput input = new TransactionInput(
+                    params, req.tx, new byte[] {}, lockTimeVerifyOutput.getOutPointFor());
+            input.setSequenceNumber(0);
+            req.tx.addInput(input);
+            TransactionSignature sig =
+                    req.tx.calculateSignature(0, key, lockTimeVerifyOutput.getScriptPubKey(), Transaction.SigHash.SINGLE, false);
+            input.setScriptSig(ScriptBuilder.createCLTVPaymentChannelRefund(sig));
+
+            System.out.println(req.tx.getHashAsString());
+            if (options.has("offline")) {
+                wallet.commitTx(req.tx);
+                return;
+            }
+
+            setup();
+            peers.start();
+            // Wait for peers to connect, the tx to be sent to one of them and for it to be propagated across the
+            // network. Once propagation is complete and we heard the transaction back from all our peers, it will
+            // be committed to the wallet.
+            peers.broadcastTransaction(req.tx).future().get();
+            // Hack for regtest/single peer mode, as we're about to shut down and won't get an ACK from the remote end.
+            List<Peer> peerList = peers.getConnectedPeers();
+            if (peerList.size() == 1)
+                peerList.get(0).ping().get();
+        } catch (BlockStoreException e) {
+            throw new RuntimeException(e);
+        } catch (KeyCrypterException e) {
+            throw new RuntimeException(e);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        } catch (ExecutionException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     /**
      * Parses the string either as a whole number of blocks, or if it contains slashes as a YYYY/MM/DD format date
      * and returns the lock time in wire format.

tools/src/main/resources/org/bitcoinj/tools/wallet-tool-help.txt

@@ -62,6 +62,30 @@ Usage: wallet-tool --flags action-name
                        If --date is specified, that's the creation date.
                        If --unixtime is specified, that's the creation time and it overrides --date.
                        If you omit both options, the creation time is being cleared (set to 0).
+  send-cltvpaymentchannel
+                       Creates and broadcasts a transaction paying to a CHECKLOCKTIMEVERIFY micropayment channel.
+                       Requires a public key for the money recipient, public key to create the transactions (the
+                       "return" address) and an expiry time.
+                       Options:
+                          --output=pubkey:value sets the amount to lock and the recipient
+                          --refund-to=pubkey sets "our" public key
+                          --fee=value sets the mining fee
+                          --locktime=YYYY/MM/DD sets the expiry time for the channel
+  settle-cltvpaymentchannel
+                       Creates and broadcasts a transaction settling a previous micropayment channel.
+                       This tool, for testing, requires the presence of both private keys.
+                       Options:
+                          --output=pubkey:value sets the destination for the money
+                          --fee=value sets the mining fee
+                          --txhash=hash sets the transaction to spend
+  refund-cltvpaymentchannel
+                       Creates and broadcasts a transaction refunding a previous micropayment channel.
+                       This command can only be called once the expiry for the micropayment channel has passed -
+                       the created transaction won't be accepted into the mempool until that point.
+                       Options:
+                          --output=pubkey:value sets the destination for the money
+                          --fee=value sets the mining fee
+                          --txhash=hash sets the transaction to spend
 
 >>> GENERAL OPTIONS
   --debuglog           Enables logging from the core library.