use backup arbitrator if signing arbitrator not available

Makefile

@@ -53,6 +53,17 @@ arbitrator-desktop:
 		--appName=haveno-XMR_STAGENET_arbitrator \
 		--apiPassword=apitest \
 		--apiPort=9998
+		
+arbitrator-desktop2:
+	# Arbitrator and mediator need to be registerd in the UI after launching it.
+	./haveno-desktop \
+		--baseCurrencyNetwork=XMR_STAGENET \
+		--useLocalhostForP2P=true \
+		--useDevPrivilegeKeys=true \
+		--nodePort=7777 \
+		--appName=haveno-XMR_STAGENET_arbitrator2 \
+		--apiPassword=apitest \
+		--apiPort=10001
 
 alice-desktop:
 	./haveno-desktop \

core/src/main/java/bisq/core/offer/OfferFilter.java

@@ -216,8 +216,8 @@ public class OfferFilter {
     public boolean hasValidSignature(Offer offer) {
         
         // get arbitrator
-        Mediator arbitrator = user.getAcceptedMediatorByAddress(offer.getOfferPayload().getArbitratorNodeAddress()); // TODO (woodser): does this return null if arbitrator goes offline?
+        Mediator arbitrator = user.getAcceptedMediatorByAddress(offer.getOfferPayload().getArbitratorSigner());
-        if (arbitrator == null) return false; // TODO (woodser): if arbitrator is null, get arbirator's pub key ring from store, otherwise cannot validate and offer is not seen by takers when arbitrator goes offline
+        if (arbitrator == null) return false; // invalid arbitrator
         
         // validate arbitrator signature
         return TradeUtils.isArbitratorSignatureValid(offer.getOfferPayload(), arbitrator);

core/src/main/java/bisq/core/offer/OfferPayload.java

@@ -169,7 +169,7 @@ public final class OfferPayload implements ProtectedStoragePayload, ExpirablePay
     
     // address and signature of signing arbitrator
     @Setter
-    private NodeAddress arbitratorNodeAddress;
+    private NodeAddress arbitratorSigner;
     @Setter
     @Nullable
     private String arbitratorSignature;
@@ -255,7 +255,7 @@ public final class OfferPayload implements ProtectedStoragePayload, ExpirablePay
         this.hashOfChallenge = hashOfChallenge;
         this.extraDataMap = ExtraDataMapValidator.getValidatedExtraDataMap(extraDataMap);
         this.protocolVersion = protocolVersion;
-        this.arbitratorNodeAddress = arbitratorSigner;
+        this.arbitratorSigner = arbitratorSigner;
         this.arbitratorSignature = arbitratorSignature;
         this.reserveTxKeyImages = reserveTxKeyImages;
     }
@@ -295,7 +295,7 @@ public final class OfferPayload implements ProtectedStoragePayload, ExpirablePay
                 .setUpperClosePrice(upperClosePrice)
                 .setIsPrivateOffer(isPrivateOffer)
                 .setProtocolVersion(protocolVersion)
-                .setArbitratorNodeAddress(arbitratorNodeAddress.toProtoMessage());
+                .setArbitratorSigner(arbitratorSigner.toProtoMessage());
 
         builder.setOfferFeePaymentTxId(checkNotNull(offerFeePaymentTxId,
                 "OfferPayload is in invalid state: offerFeePaymentTxID is not set when adding to P2P network."));
@@ -357,7 +357,7 @@ public final class OfferPayload implements ProtectedStoragePayload, ExpirablePay
                 hashOfChallenge,
                 extraDataMapMap,
                 proto.getProtocolVersion(),
-                NodeAddress.fromProto(proto.getArbitratorNodeAddress()),
+                NodeAddress.fromProto(proto.getArbitratorSigner()),
                 ProtoUtil.stringOrNullFromProto(proto.getArbitratorSignature()),
                 proto.getReserveTxKeyImagesList() == null ? null : new ArrayList<String>(proto.getReserveTxKeyImagesList()));
     }
@@ -424,7 +424,7 @@ public final class OfferPayload implements ProtectedStoragePayload, ExpirablePay
                 ",\n     hashOfChallenge='" + hashOfChallenge + '\'' +
                 ",\n     extraDataMap=" + extraDataMap +
                 ",\n     protocolVersion=" + protocolVersion +
-                ",\n     arbitratorSigner=" + arbitratorNodeAddress +
+                ",\n     arbitratorSigner=" + arbitratorSigner +
                 ",\n     arbitratorSignature=" + arbitratorSignature +
                 "\n}";
     }

core/src/main/java/bisq/core/offer/OpenOffer.java

@@ -24,9 +24,7 @@ import bisq.network.p2p.NodeAddress;
 import bisq.common.Timer;
 import bisq.common.UserThread;
 import bisq.common.proto.ProtoUtil;
-import java.util.ArrayList;
 import java.util.Date;
-import java.util.List;
 import java.util.Optional;
 
 import lombok.EqualsAndHashCode;
@@ -58,10 +56,17 @@ public final class OpenOffer implements Tradable {
     @Getter
     @Setter
     @Nullable
-    private NodeAddress arbitratorNodeAddress;
+    private NodeAddress backupArbitrator;
     @Setter
     @Getter
-    private List<String> frozenKeyImages = new ArrayList<>();
+    private String reserveTxHash;
+    @Setter
+    @Getter
+    private String reserveTxHex;
+    @Setter
+    @Getter
+    private String reserveTxKey;
+    
 
     // Added in v1.5.3.
     // If market price reaches that trigger price the offer gets deactivated
@@ -81,11 +86,17 @@ public final class OpenOffer implements Tradable {
         state = State.AVAILABLE;
     }
     
-    public OpenOffer(Offer offer, long triggerPrice, List<String> frozenKeyImages) {
+    public OpenOffer(Offer offer,
+                     long triggerPrice,
+                     String reserveTxHash,
+                     String reserveTxHex,
+                     String reserveTxKey) {
         this.offer = offer;
         this.triggerPrice = triggerPrice;
         state = State.AVAILABLE;
-        this.frozenKeyImages = frozenKeyImages;
+        this.reserveTxHash = reserveTxHash;
+        this.reserveTxHex = reserveTxHex;
+        this.reserveTxKey = reserveTxKey;
     }
 
     ///////////////////////////////////////////////////////////////////////////////////////////
@@ -94,12 +105,18 @@ public final class OpenOffer implements Tradable {
 
     private OpenOffer(Offer offer,
                       State state,
-                      @Nullable NodeAddress arbitratorNodeAddress,
+                      @Nullable NodeAddress backupArbitrator,
-                      long triggerPrice) {
+                      long triggerPrice,
+                      String reserveTxHash,
+                      String reserveTxHex,
+                      String reserveTxKey) {
         this.offer = offer;
         this.state = state;
-        this.arbitratorNodeAddress = arbitratorNodeAddress;
+        this.backupArbitrator = backupArbitrator;
         this.triggerPrice = triggerPrice;
+        this.reserveTxHash = reserveTxHash;
+        this.reserveTxHex = reserveTxHex;
+        this.reserveTxKey = reserveTxKey;
 
         if (this.state == State.RESERVED)
             setState(State.AVAILABLE);
@@ -111,9 +128,11 @@ public final class OpenOffer implements Tradable {
                 .setOffer(offer.toProtoMessage())
                 .setTriggerPrice(triggerPrice)
                 .setState(protobuf.OpenOffer.State.valueOf(state.name()))
-                .addAllFrozenKeyImages(frozenKeyImages);
+                .setReserveTxHash(reserveTxHash)
+                .setReserveTxHex(reserveTxHex)
+                .setReserveTxKey(reserveTxKey);
 
-        Optional.ofNullable(arbitratorNodeAddress).ifPresent(nodeAddress -> builder.setArbitratorNodeAddress(nodeAddress.toProtoMessage()));
+        Optional.ofNullable(backupArbitrator).ifPresent(nodeAddress -> builder.setBackupArbitrator(nodeAddress.toProtoMessage()));
 
         return protobuf.Tradable.newBuilder().setOpenOffer(builder).build();
     }
@@ -121,9 +140,11 @@ public final class OpenOffer implements Tradable {
     public static Tradable fromProto(protobuf.OpenOffer proto) {
         OpenOffer openOffer = new OpenOffer(Offer.fromProto(proto.getOffer()),
                 ProtoUtil.enumFromProto(OpenOffer.State.class, proto.getState().name()),
-                proto.hasArbitratorNodeAddress() ? NodeAddress.fromProto(proto.getArbitratorNodeAddress()) : null,
+                proto.hasBackupArbitrator() ? NodeAddress.fromProto(proto.getBackupArbitrator()) : null,
-                proto.getTriggerPrice());
+                proto.getTriggerPrice(),
-        openOffer.setFrozenKeyImages(proto.getFrozenKeyImagesList());
+                proto.getReserveTxHash(),
+                proto.getReserveTxHex(),
+                proto.getReserveTxKey());
         return openOffer;
     }
 
@@ -187,7 +208,7 @@ public final class OpenOffer implements Tradable {
         return "OpenOffer{" +
                 ",\n     offer=" + offer +
                 ",\n     state=" + state +
-                ",\n     arbitratorNodeAddress=" + arbitratorNodeAddress +
+                ",\n     arbitratorNodeAddress=" + backupArbitrator +
                 ",\n     triggerPrice=" + triggerPrice +
                 "\n}";
     }

core/src/main/java/bisq/core/offer/OpenOfferManager.java

@@ -91,7 +91,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import lombok.Getter;
-import monero.daemon.model.MoneroOutput;
 import org.jetbrains.annotations.NotNull;
 
 import javax.annotation.Nullable;
@@ -416,10 +415,8 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
                 model,
                 transaction -> {
                     
-                    // save frozen key images with open offer
+                    // save reserve tx with open offer
-                    List<String> frozenKeyImages = new ArrayList<String>();
+                    OpenOffer openOffer = new OpenOffer(offer, triggerPrice, model.getReserveTx().getHash(), model.getReserveTx().getFullHex(), model.getReserveTx().getKey());
-                    for (MoneroOutput output : model.getReserveTx().getInputs()) frozenKeyImages.add(output.getKeyImage().getHex());
-                    OpenOffer openOffer = new OpenOffer(offer, triggerPrice, frozenKeyImages);
                     openOffers.add(openOffer);
                     requestPersistence();
                     resultHandler.handleResult(transaction);
@@ -577,7 +574,7 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
         closedTradableManager.add(openOffer);
         log.info("onRemoved offerId={}", offer.getId());
         btcWalletService.resetAddressEntriesForOpenOffer(offer.getId());
-        for (String frozenKeyImage : openOffer.getFrozenKeyImages()) xmrWalletService.getWallet().thawOutput(frozenKeyImage);
+        for (String frozenKeyImage : offer.getOfferPayload().getReserveTxKeyImages()) xmrWalletService.getWallet().thawOutput(frozenKeyImage);
         requestPersistence();
         resultHandler.handleResult();
     }
@@ -642,7 +639,7 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
             }
             
             // verify arbitrator is signer of offer payload
-            if (!request.getOfferPayload().getArbitratorNodeAddress().equals(thisAddress)) {
+            if (!thisAddress.equals(request.getOfferPayload().getArbitratorSigner())) {
                 errorMessage = "Cannot sign offer because offer payload is for a different arbitrator";
                 log.info(errorMessage);
                 sendAckMessage(request.getClass(), peer, request.getPubKeyRing(), request.getOfferId(), request.getUid(), false, errorMessage);
@@ -784,7 +781,7 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
             Optional<OpenOffer> openOfferOptional = getOpenOfferById(request.offerId);
             AvailabilityResult availabilityResult;
             String makerSignature = null;
-            NodeAddress arbitratorNodeAddress = null;
+            NodeAddress backupArbitratorNodeAddress = null;
             if (openOfferOptional.isPresent()) {
                 OpenOffer openOffer = openOfferOptional.get();
                 if (!apiUserDeniedByOffer(request)) {
@@ -793,10 +790,10 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
                             Offer offer = openOffer.getOffer();
                             if (preferences.getIgnoreTradersList().stream().noneMatch(fullAddress -> fullAddress.equals(peer.getFullAddress()))) {
                                 
-                                // use signing arbitrator if available, otherwise use least used arbitrator
+                                // set backup arbitrator if signer is not available
-                                boolean isSignerOnline = true;
+                                Mediator backupMediator = DisputeAgentSelection.getLeastUsedArbitrator(tradeStatisticsManager, mediatorManager, offer.getOfferPayload().getArbitratorSigner());
-                                arbitratorNodeAddress = isSignerOnline ? offer.getOfferPayload().getArbitratorNodeAddress() : DisputeAgentSelection.getLeastUsedArbitrator(tradeStatisticsManager, mediatorManager).getNodeAddress();
+                                backupArbitratorNodeAddress = backupMediator == null ? null : backupMediator.getNodeAddress();
-                                openOffer.setArbitratorNodeAddress(arbitratorNodeAddress);
+                                openOffer.setBackupArbitrator(backupArbitratorNodeAddress);
                                 
                                 // maker signs taker's request // TODO (woodser): should maker signature include selected arbitrator?
                                 String tradeRequestAsJson = Utilities.objectToJson(request.getTradeRequest());
@@ -848,7 +845,7 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
             OfferAvailabilityResponse offerAvailabilityResponse = new OfferAvailabilityResponse(request.offerId,
                     availabilityResult,
                     makerSignature,
-                    arbitratorNodeAddress);
+                    backupArbitratorNodeAddress);
             log.info("Send {} with offerId {} and uid {} to peer {}",
                     offerAvailabilityResponse.getClass().getSimpleName(), offerAvailabilityResponse.getOfferId(),
                     offerAvailabilityResponse.getUid(), peer);
@@ -933,6 +930,8 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
     ///////////////////////////////////////////////////////////////////////////////////////////
     // Update persisted offer if a new capability is required after a software update
     ///////////////////////////////////////////////////////////////////////////////////////////
+    
+    // TODO (woodser): arbitrator signature will be invalid if offer updated (exclude updateable fields from signature? re-sign?)
 
     private void maybeUpdatePersistedOffers() {
         // We need to clone to avoid ConcurrentModificationException
@@ -1019,7 +1018,7 @@ public class OpenOfferManager implements PeerManager.Listener, DecryptedDirectMe
                         originalOfferPayload.getHashOfChallenge(),
                         updatedExtraDataMap,
                         protocolVersion,
-                        originalOfferPayload.getArbitratorNodeAddress(),
+                        originalOfferPayload.getArbitratorSigner(),
                         originalOfferPayload.getArbitratorSignature(),
                         originalOfferPayload.getReserveTxKeyImages());
 

core/src/main/java/bisq/core/offer/availability/DisputeAgentSelection.java

@@ -21,7 +21,7 @@ import bisq.core.support.dispute.agent.DisputeAgent;
 import bisq.core.support.dispute.agent.DisputeAgentManager;
 import bisq.core.trade.statistics.TradeStatistics3;
 import bisq.core.trade.statistics.TradeStatisticsManager;
-
+import bisq.network.p2p.NodeAddress;
 import bisq.common.util.Tuple2;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -43,15 +43,25 @@ import static com.google.common.base.Preconditions.checkArgument;
 @Slf4j
 public class DisputeAgentSelection {
     public static final int LOOK_BACK_RANGE = 100;
-
+    
     public static <T extends DisputeAgent> T getLeastUsedArbitrator(TradeStatisticsManager tradeStatisticsManager,
                                                                   DisputeAgentManager<T> disputeAgentManager) {
         return getLeastUsedDisputeAgent(tradeStatisticsManager,
-                disputeAgentManager);
+                disputeAgentManager,
+                null);
+}
+
+    public static <T extends DisputeAgent> T getLeastUsedArbitrator(TradeStatisticsManager tradeStatisticsManager,
+                                                                  DisputeAgentManager<T> disputeAgentManager,
+                                                                  NodeAddress excludedArbitrator) {
+        return getLeastUsedDisputeAgent(tradeStatisticsManager,
+                disputeAgentManager,
+                excludedArbitrator);
     }
 
     private static <T extends DisputeAgent> T getLeastUsedDisputeAgent(TradeStatisticsManager tradeStatisticsManager,
-                                                                       DisputeAgentManager<T> disputeAgentManager) {
+                                                                       DisputeAgentManager<T> disputeAgentManager,
+                                                                       NodeAddress excludedDisputeAgent) {
         // We take last 100 entries from trade statistics
         List<TradeStatistics3> list = new ArrayList<>(tradeStatisticsManager.getObservableTradeStatisticsSet());
         list.sort(Comparator.comparing(TradeStatistics3::getDateAsLong));
@@ -71,6 +81,9 @@ public class DisputeAgentSelection {
                 .map(disputeAgent -> disputeAgent.getNodeAddress().getFullAddress())
                 .collect(Collectors.toSet());
 
+        if (excludedDisputeAgent != null) disputeAgents.remove(excludedDisputeAgent.getFullAddress());
+        if (disputeAgents.isEmpty()) return null;
+
         String result = getLeastUsedDisputeAgent(lastAddressesUsedInTrades, disputeAgents);
 
         Optional<T> optionalDisputeAgent = disputeAgentManager.getObservableMap().values().stream()

core/src/main/java/bisq/core/offer/availability/OfferAvailabilityModel.java

@@ -67,7 +67,7 @@ public class OfferAvailabilityModel implements Model {
     private String makerSignature;
     @Setter
     @Getter
-    private NodeAddress arbitratorNodeAddress;
+    private NodeAddress backupArbitrator;
 
     // Added in v1.5.5
     @Getter

core/src/main/java/bisq/core/offer/availability/tasks/ProcessOfferAvailabilityResponse.java

@@ -53,19 +53,17 @@ public class ProcessOfferAvailabilityResponse extends Task<OfferAvailabilityMode
                 return;
             }
             
-            // check maker signature for trade request
+            // verify maker signature for trade request
             if (!TradeUtils.isMakerSignatureValid(model.getTradeRequest(), offerAvailabilityResponse.getMakerSignature(), offer.getPubKeyRing())) {
                 offer.setState(Offer.State.NOT_AVAILABLE);
                 failed("Take offer attempt failed because maker signature is invalid");
                 return;
             }
-
-            offer.setState(Offer.State.AVAILABLE);
             
+            offer.setState(Offer.State.AVAILABLE);
             model.setMakerSignature(offerAvailabilityResponse.getMakerSignature());
-            model.setArbitratorNodeAddress(offerAvailabilityResponse.getArbitratorNodeAddress());
+            model.setBackupArbitrator(offerAvailabilityResponse.getBackupArbitrator());
             checkNotNull(model.getMakerSignature());
-            checkNotNull(model.getArbitratorNodeAddress());
 
             complete();
         } catch (Throwable t) {

core/src/main/java/bisq/core/offer/availability/tasks/SendOfferAvailabilityRequest.java

@@ -37,6 +37,7 @@ import bisq.common.taskrunner.TaskRunner;
 
 import lombok.extern.slf4j.Slf4j;
 
+// TODO (woodser): rename to TakerSendOfferAvailabilityRequest and group with other taker tasks
 @Slf4j
 public class SendOfferAvailabilityRequest extends Task<OfferAvailabilityModel> {
     public SendOfferAvailabilityRequest(TaskRunner<OfferAvailabilityModel> taskHandler, OfferAvailabilityModel model) {
@@ -78,7 +79,7 @@ public class SendOfferAvailabilityRequest extends Task<OfferAvailabilityModel> {
                     new Date().getTime(),
                     offer.getMakerNodeAddress(),
                     P2PService.getMyNodeAddress(),
-                    null, // maker provides node address of arbitrator on response
+                    null, // maker provides node address of backup arbitrator on response
                     null, // reserve tx not sent from taker to maker
                     null,
                     null,

core/src/main/java/bisq/core/offer/messages/OfferAvailabilityResponse.java

@@ -46,19 +46,19 @@ public final class OfferAvailabilityResponse extends OfferMessage implements Sup
 
     @Nullable
     private final String makerSignature;
-    private final NodeAddress arbitratorNodeAddress;
+    private final NodeAddress backupArbitrator;
 
     public OfferAvailabilityResponse(String offerId,
                                      AvailabilityResult availabilityResult,
                                      String makerSignature,
-                                     NodeAddress arbitratorNodeAddress) {
+                                     NodeAddress backupArbitrator) {
         this(offerId,
                 availabilityResult,
                 Capabilities.app,
                 Version.getP2PMessageVersion(),
                 UUID.randomUUID().toString(),
                 makerSignature,
-                arbitratorNodeAddress);
+                backupArbitrator);
     }
 
 
@@ -77,19 +77,19 @@ public final class OfferAvailabilityResponse extends OfferMessage implements Sup
         this.availabilityResult = availabilityResult;
         this.supportedCapabilities = supportedCapabilities;
         this.makerSignature = makerSignature;
-        this.arbitratorNodeAddress = arbitratorNodeAddress;
+        this.backupArbitrator = arbitratorNodeAddress;
     }
 
     @Override
     public protobuf.NetworkEnvelope toProtoNetworkEnvelope() {
         final protobuf.OfferAvailabilityResponse.Builder builder = protobuf.OfferAvailabilityResponse.newBuilder()
                 .setOfferId(offerId)
-                .setAvailabilityResult(protobuf.AvailabilityResult.valueOf(availabilityResult.name()))
+                .setAvailabilityResult(protobuf.AvailabilityResult.valueOf(availabilityResult.name()));
-                .setArbitratorNodeAddress(arbitratorNodeAddress.toProtoMessage());
 
         Optional.ofNullable(supportedCapabilities).ifPresent(e -> builder.addAllSupportedCapabilities(Capabilities.toIntList(supportedCapabilities)));
         Optional.ofNullable(uid).ifPresent(e -> builder.setUid(uid));
         Optional.ofNullable(makerSignature).ifPresent(e -> builder.setMakerSignature(makerSignature));
+        Optional.ofNullable(backupArbitrator).ifPresent(nodeAddress -> builder.setBackupArbitrator(nodeAddress.toProtoMessage()));
 
         return getNetworkEnvelopeBuilder()
                 .setOfferAvailabilityResponse(builder)
@@ -103,6 +103,6 @@ public final class OfferAvailabilityResponse extends OfferMessage implements Sup
                 messageVersion,
                 proto.getUid().isEmpty() ? null : proto.getUid(),
                 proto.getMakerSignature().isEmpty() ? null : proto.getMakerSignature(),
-                NodeAddress.fromProto(proto.getArbitratorNodeAddress()));
+                proto.hasBackupArbitrator() ? NodeAddress.fromProto(proto.getBackupArbitrator()) : null);
     }
 }

core/src/main/java/bisq/core/offer/placeoffer/PlaceOfferProtocol.java

@@ -56,6 +56,7 @@ public class PlaceOfferProtocol {
     // Called from UI
     ///////////////////////////////////////////////////////////////////////////////////////////
 
+    // TODO (woodser): this returns before offer is placed
     public void placeOffer() {
         log.debug("placeOffer() " + model.getOffer().getId());
         TaskRunner<PlaceOfferModel> taskRunner = new TaskRunner<>(model,
@@ -82,7 +83,7 @@ public class PlaceOfferProtocol {
       log.debug("handleSignOfferResponse() " + model.getOffer().getId());
       model.setSignOfferResponse(response);
       
-      if (!model.getOffer().getOfferPayload().getArbitratorNodeAddress().equals(sender)) {
+      if (!model.getOffer().getOfferPayload().getArbitratorSigner().equals(sender)) {
           log.warn("Ignoring sign offer response from different sender");
           return;
       }

core/src/main/java/bisq/core/offer/placeoffer/tasks/MakerProcessesSignOfferResponse.java

@@ -39,7 +39,7 @@ public class MakerProcessesSignOfferResponse extends Task<PlaceOfferModel> {
             runInterceptHook();
             
             // validate arbitrator signature
-            Mediator arbitrator = checkNotNull(model.getUser().getAcceptedMediatorByAddress(offer.getOfferPayload().getArbitratorNodeAddress()), "user.getAcceptedMediatorByAddress(arbitratorNodeAddress) must not be null");
+            Mediator arbitrator = checkNotNull(model.getUser().getAcceptedMediatorByAddress(offer.getOfferPayload().getArbitratorSigner()), "user.getAcceptedMediatorByAddress(arbitratorSigner) must not be null");
             if (!TradeUtils.isArbitratorSignatureValid(model.getSignOfferResponse().getSignedOfferPayload(), arbitrator)) {
                 throw new RuntimeException("Offer payload has invalid arbitrator signature");
             }

core/src/main/java/bisq/core/offer/placeoffer/tasks/MakerReservesTradeFunds.java

@@ -64,7 +64,7 @@ public class MakerReservesTradeFunds extends Task<PlaceOfferModel> {
             // TODO (woodser): persist
             model.setReserveTx(reserveTx);
             offer.getOfferPayload().setReserveTxKeyImages(reservedKeyImages);
-            offer.setOfferFeePaymentTxId(reserveTx.getHash()); // TODO (woodser): rename this to reserve tx id
+            offer.setOfferFeePaymentTxId(reserveTx.getHash()); // TODO (woodser): don't use this field
             offer.setState(Offer.State.OFFER_FEE_RESERVED);
             complete();
         } catch (Throwable t) {

core/src/main/java/bisq/core/offer/placeoffer/tasks/MakerSendsSignOfferRequest.java

@@ -68,7 +68,7 @@ public class MakerSendsSignOfferRequest extends Task<PlaceOfferModel> {
                     returnAddress);
             
             // get signing arbitrator
-            Mediator arbitrator = checkNotNull(model.getUser().getAcceptedMediatorByAddress(offer.getOfferPayload().getArbitratorNodeAddress()), "user.getAcceptedMediatorByAddress(mediatorNodeAddress) must not be null");
+            Mediator arbitrator = checkNotNull(model.getUser().getAcceptedMediatorByAddress(offer.getOfferPayload().getArbitratorSigner()), "user.getAcceptedMediatorByAddress(mediatorNodeAddress) must not be null");
 
             // send request
             model.getP2PService().sendEncryptedDirectMessage(arbitrator.getNodeAddress(), arbitrator.getPubKeyRing(), request, new SendDirectMessageListener() {

core/src/main/java/bisq/core/trade/TradeManager.java

@@ -433,11 +433,13 @@ public class TradeManager implements PersistedDataHost, DecryptedDirectMessageLi
                       request.getTakerNodeAddress(),
                       request.getArbitratorNodeAddress());
 
-              // set reserve tx hash
+              // set reserve tx hash if available
               Optional<SignedOffer> signedOfferOptional = openOfferManager.getSignedOfferById(request.getTradeId());
-              if (!signedOfferOptional.isPresent()) return;
+              if (signedOfferOptional.isPresent()) {
-              SignedOffer signedOffer = signedOfferOptional.get();
+                  SignedOffer signedOffer = signedOfferOptional.get();
-              trade.getMaker().setReserveTxHash(signedOffer.getReserveTxHash());
+                  trade.getMaker().setReserveTxHash(signedOffer.getReserveTxHash());
+              }
+
               initTradeAndProtocol(trade, getTradeProtocol(trade));
               tradableList.add(trade);
           }
@@ -464,20 +466,15 @@ public class TradeManager implements PersistedDataHost, DecryptedDirectMessageLi
           }
 
           Offer offer = openOffer.getOffer();
-          openOfferManager.reserveOpenOffer(openOffer); // TODO (woodser): reserve offer if arbitrator?
 
-          // verify request is from signing arbitrator when they're online, else from selected arbitrator
+          // verify request is from signer or backup arbitrator
-          if (!sender.equals(offer.getOfferPayload().getArbitratorNodeAddress())) {
+          if (!sender.equals(offer.getOfferPayload().getArbitratorSigner()) && !sender.equals(openOffer.getBackupArbitrator())) { // TODO (woodser): get backup arbitrator from maker-signed InitTradeRequest and remove from OpenOffer
-              boolean isSignerOnline = true; // TODO (woodser): determine if signer is online and test
+              log.warn("Ignoring InitTradeRequest from {} with tradeId {} because request must be from signer or backup arbitrator", sender, request.getTradeId());
-              if (isSignerOnline) {
+              return;
-                  log.warn("Ignoring InitTradeRequest from {} with tradeId {} because request must be from signing arbitrator when online", sender, request.getTradeId());
-                  return;
-              } else if (!sender.equals(openOffer.getArbitratorNodeAddress())) {
-                  log.warn("Ignoring InitTradeRequest from {} with tradeId {} because request must be from selected arbitrator when signing arbitrator is offline", sender, request.getTradeId());
-                  return;
-              }
           }
 
+          openOfferManager.reserveOpenOffer(openOffer); // TODO (woodser): reserve offer if arbitrator?
+
           Trade trade;
           if (offer.isBuyOffer())
               trade = new BuyerAsMakerTrade(offer,
@@ -504,12 +501,14 @@ public class TradeManager implements PersistedDataHost, DecryptedDirectMessageLi
 
           //System.out.println("TradeManager trade.setTradingPeerNodeAddress(): " + sender);
           //trade.setTradingPeerNodeAddress(sender);
-          // TODO (woodser): what if maker's address changes while offer open, or taker's address changes after multisig deposit available? need to verify and update
+          // TODO (woodser): what if maker's address changes while offer open, or taker's address changes after multisig deposit available? need to verify and update. see OpenOfferManager.maybeUpdatePersistedOffers()
           trade.setArbitratorPubKeyRing(user.getAcceptedMediatorByAddress(sender).getPubKeyRing());
           trade.setMakerPubKeyRing(trade.getOffer().getPubKeyRing());
           initTradeAndProtocol(trade, getTradeProtocol(trade));
-          trade.getProcessModel().setReserveTxHash(offer.getOfferFeePaymentTxId()); // TODO (woodser): initialize in initTradeAndProtocol ?
+          trade.getSelf().setReserveTxHash(openOffer.getReserveTxHash()); // TODO (woodser): initialize in initTradeAndProtocol?
-          trade.getProcessModel().setFrozenKeyImages(openOffer.getFrozenKeyImages());
+          trade.getSelf().setReserveTxHex(openOffer.getReserveTxHex());
+          trade.getSelf().setReserveTxKey(openOffer.getReserveTxKey());
+          trade.getSelf().setReserveTxKeyImages(offer.getOfferPayload().getReserveTxKeyImages());
           tradableList.add(trade);
 
           ((MakerProtocol) getTradeProtocol(trade)).handleInitTradeRequest(request,  sender, errorMessage -> {
@@ -702,7 +701,7 @@ public class TradeManager implements PersistedDataHost, DecryptedDirectMessageLi
                                     UUID.randomUUID().toString(),
                                     model.getPeerNodeAddress(),
                                     P2PService.getMyNodeAddress(),
-                                    offer.getOfferPayload().getArbitratorNodeAddress());
+                                    offer.getOfferPayload().getArbitratorSigner());
                         } else {
                             trade = new BuyerAsTakerTrade(offer,
                                     amount,
@@ -713,12 +712,12 @@ public class TradeManager implements PersistedDataHost, DecryptedDirectMessageLi
                                     UUID.randomUUID().toString(),
                                     model.getPeerNodeAddress(),
                                     P2PService.getMyNodeAddress(),
-                                    offer.getOfferPayload().getArbitratorNodeAddress());
+                                    offer.getOfferPayload().getArbitratorSigner());
                         }
 
                         trade.getProcessModel().setTradeMessage(model.getTradeRequest());
                         trade.getProcessModel().setMakerSignature(model.getMakerSignature());
-                        trade.getProcessModel().setArbitratorNodeAddress(model.getArbitratorNodeAddress());
+                        trade.getProcessModel().setBackupArbitrator(model.getBackupArbitrator()); // backup arbitrator only used if signer offline
                         trade.getProcessModel().setUseSavingsWallet(useSavingsWallet);
                         trade.getProcessModel().setFundsNeededForTradeAsLong(fundsNeededForTrade.value);
                         trade.setTakerPubKeyRing(model.getPubKeyRing());

core/src/main/java/bisq/core/trade/protocol/ArbitratorProtocol.java

@@ -7,11 +7,10 @@ import bisq.core.trade.messages.InitMultisigRequest;
 import bisq.core.trade.messages.InitTradeRequest;
 import bisq.core.trade.messages.SignContractRequest;
 import bisq.core.trade.protocol.tasks.ApplyFilter;
-import bisq.core.trade.protocol.tasks.ArbitratorSendsInitTradeRequestToMakerIfFromTaker;
+import bisq.core.trade.protocol.tasks.ArbitratorSendsInitTradeAndMultisigRequests;
 import bisq.core.trade.protocol.tasks.ProcessDepositRequest;
 import bisq.core.trade.protocol.tasks.ProcessInitMultisigRequest;
 import bisq.core.trade.protocol.tasks.ArbitratorProcessesReserveTx;
-import bisq.core.trade.protocol.tasks.ArbitratorSendsInitMultisigRequestsIfFundsReserved;
 import bisq.core.trade.protocol.tasks.ProcessInitTradeRequest;
 import bisq.core.trade.protocol.tasks.ProcessSignContractRequest;
 import bisq.core.util.Validator;
@@ -42,8 +41,7 @@ public class ArbitratorProtocol extends DisputeProtocol {
                   ApplyFilter.class,
                   ProcessInitTradeRequest.class,
                   ArbitratorProcessesReserveTx.class,
-                  ArbitratorSendsInitTradeRequestToMakerIfFromTaker.class,
+                  ArbitratorSendsInitTradeAndMultisigRequests.class))
-                  ArbitratorSendsInitMultisigRequestsIfFundsReserved.class))
               .executeTasks();
   }
   

core/src/main/java/bisq/core/trade/protocol/BuyerAsMakerProtocol.java

@@ -42,6 +42,7 @@ import bisq.core.trade.protocol.tasks.buyer.BuyerSendsDelayedPayoutTxSignatureRe
 import bisq.core.trade.protocol.tasks.buyer.BuyerSignsDelayedPayoutTx;
 import bisq.core.trade.protocol.tasks.buyer.BuyerVerifiesPreparedDelayedPayoutTx;
 import bisq.core.trade.protocol.tasks.maker.MakerRemovesOpenOffer;
+import bisq.core.trade.protocol.tasks.maker.MakerSendsInitTradeRequestIfUnreserved;
 import bisq.core.trade.protocol.tasks.maker.MakerVerifyTakerFeePayment;
 import bisq.core.util.Validator;
 
@@ -142,7 +143,7 @@ public class BuyerAsMakerProtocol extends BuyerProtocol implements MakerProtocol
                     ProcessInitTradeRequest.class,
                     //ApplyFilter.class, // TODO (woodser): these checks apply when maker signs availability request, but not here
                     //VerifyPeersAccountAgeWitness.class, // TODO (woodser): these checks apply after in multisig, means if rejected need to reimburse other's fee
-                    //MakerSendsInitTradeRequestIfUnreserved.class, // TODO (woodser): implement this
+                    MakerSendsInitTradeRequestIfUnreserved.class,
                     MakerRemovesOpenOffer.class).
                     using(new TradeTaskRunner(trade,
                             () -> {

core/src/main/java/bisq/core/trade/protocol/BuyerAsTakerProtocol.java

@@ -76,9 +76,9 @@ public class BuyerAsTakerProtocol extends BuyerProtocol implements TakerProtocol
 
     public BuyerAsTakerProtocol(BuyerAsTakerTrade trade) {
         super(trade);
-
         Offer offer = checkNotNull(trade.getOffer());
         trade.getTradingPeer().setPubKeyRing(offer.getPubKeyRing());
+        trade.setMakerPubKeyRing(offer.getPubKeyRing());
 
        // TODO (woodser): setup deposit and payout listeners on construction for startup like before rebase?
     }
@@ -100,7 +100,7 @@ public class BuyerAsTakerProtocol extends BuyerProtocol implements TakerProtocol
           .setup(tasks(
               ApplyFilter.class,
               TakerReservesTradeFunds.class,
-              TakerSendsInitTradeRequestToArbitrator.class)
+              TakerSendsInitTradeRequestToArbitrator.class) // TODO (woodser): app hangs if this pipeline fails. use .using() like below
           .withTimeout(30))
           .executeTasks();
     }

core/src/main/java/bisq/core/trade/protocol/ProcessModel.java

@@ -25,7 +25,6 @@ import bisq.core.btc.wallet.XmrWalletService;
 import bisq.core.filter.FilterManager;
 import bisq.core.network.MessageState;
 import bisq.core.offer.Offer;
-import bisq.core.offer.OfferPayload.Direction;
 import bisq.core.offer.OpenOfferManager;
 import bisq.core.payment.PaymentAccount;
 import bisq.core.payment.payload.PaymentAccountPayload;
@@ -33,9 +32,7 @@ import bisq.core.proto.CoreProtoResolver;
 import bisq.core.support.dispute.arbitration.arbitrator.ArbitratorManager;
 import bisq.core.support.dispute.mediation.mediator.MediatorManager;
 import bisq.core.support.dispute.refund.refundagent.RefundAgentManager;
-import bisq.core.trade.ArbitratorTrade;
 import bisq.core.trade.MakerTrade;
-import bisq.core.trade.TakerTrade;
 import bisq.core.trade.Trade;
 import bisq.core.trade.TradeManager;
 import bisq.core.trade.messages.TradeMessage;
@@ -60,7 +57,6 @@ import org.bitcoinj.core.Transaction;
 
 import javafx.beans.property.ObjectProperty;
 import javafx.beans.property.SimpleObjectProperty;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.stream.Collectors;
@@ -145,7 +141,7 @@ public class ProcessModel implements Model, PersistablePayload {
     // After successful verified we copy that over to the trade.tradingPeerAddress
     @Nullable
     @Setter
-    private NodeAddress tempTradingPeerNodeAddress; // TODO (woodser): remove entirely
+    private NodeAddress tempTradingPeerNodeAddress; // TODO (woodser): remove entirely?
 
     // Added in v.1.1.6
     @Nullable
@@ -166,17 +162,11 @@ public class ProcessModel implements Model, PersistablePayload {
     private String makerSignature;
     @Getter
     @Setter
-    private NodeAddress arbitratorNodeAddress;
+    private NodeAddress backupArbitrator;
     @Nullable
     @Getter
     @Setter
     transient private MoneroTxWallet reserveTx;
-    @Setter
-    @Getter
-    private String reserveTxHash;
-    @Setter
-    @Getter
-    private List<String> frozenKeyImages = new ArrayList<>();
     @Getter
     @Setter
     transient private MoneroTxWallet depositTxXmr;
@@ -247,20 +237,18 @@ public class ProcessModel implements Model, PersistablePayload {
                 .setFundsNeededForTradeAsLong(fundsNeededForTradeAsLong)
                 .setPaymentStartedMessageState(paymentStartedMessageStateProperty.get().name())
                 .setBuyerPayoutAmountFromMediation(buyerPayoutAmountFromMediation)
-                .setSellerPayoutAmountFromMediation(sellerPayoutAmountFromMediation)
+                .setSellerPayoutAmountFromMediation(sellerPayoutAmountFromMediation);
-                .addAllFrozenKeyImages(frozenKeyImages);
         Optional.ofNullable(maker).ifPresent(e -> builder.setMaker((protobuf.TradingPeer) maker.toProtoMessage()));
         Optional.ofNullable(taker).ifPresent(e -> builder.setTaker((protobuf.TradingPeer) taker.toProtoMessage()));
         Optional.ofNullable(arbitrator).ifPresent(e -> builder.setArbitrator((protobuf.TradingPeer) arbitrator.toProtoMessage()));
         Optional.ofNullable(takeOfferFeeTxId).ifPresent(builder::setTakeOfferFeeTxId);
-        Optional.ofNullable(reserveTxHash).ifPresent(e -> builder.setReserveTxHash(reserveTxHash));
         Optional.ofNullable(payoutTxSignature).ifPresent(e -> builder.setPayoutTxSignature(ByteString.copyFrom(payoutTxSignature)));
         Optional.ofNullable(rawTransactionInputs).ifPresent(e -> builder.addAllRawTransactionInputs(ProtoUtil.collectionToProto(rawTransactionInputs, protobuf.RawTransactionInput.class)));
         Optional.ofNullable(changeOutputAddress).ifPresent(builder::setChangeOutputAddress);
         Optional.ofNullable(myMultiSigPubKey).ifPresent(e -> builder.setMyMultiSigPubKey(ByteString.copyFrom(myMultiSigPubKey)));
         Optional.ofNullable(tempTradingPeerNodeAddress).ifPresent(e -> builder.setTempTradingPeerNodeAddress(tempTradingPeerNodeAddress.toProtoMessage()));
         Optional.ofNullable(makerSignature).ifPresent(e -> builder.setMakerSignature(makerSignature));
-        Optional.ofNullable(arbitratorNodeAddress).ifPresent(e -> builder.setArbitratorNodeAddress(arbitratorNodeAddress.toProtoMessage()));
+        Optional.ofNullable(backupArbitrator).ifPresent(e -> builder.setBackupArbitrator(backupArbitrator.toProtoMessage()));
         Optional.ofNullable(preparedMultisigHex).ifPresent(e -> builder.setPreparedMultisigHex(preparedMultisigHex));
         Optional.ofNullable(madeMultisigHex).ifPresent(e -> builder.setMadeMultisigHex(madeMultisigHex));
         Optional.ofNullable(multisigSetupComplete).ifPresent(e -> builder.setMultisigSetupComplete(multisigSetupComplete));
@@ -282,8 +270,6 @@ public class ProcessModel implements Model, PersistablePayload {
         processModel.setSellerPayoutAmountFromMediation(proto.getSellerPayoutAmountFromMediation());
 
         // nullable
-        processModel.setReserveTxHash(proto.getReserveTxHash());
-        processModel.setFrozenKeyImages(proto.getFrozenKeyImagesList());
         processModel.setTakeOfferFeeTxId(ProtoUtil.stringOrNullFromProto(proto.getTakeOfferFeeTxId()));
         processModel.setPayoutTxSignature(ProtoUtil.byteArrayOrNullFromProto(proto.getPayoutTxSignature()));
         List<RawTransactionInput> rawTransactionInputs = proto.getRawTransactionInputsList().isEmpty() ?
@@ -295,7 +281,7 @@ public class ProcessModel implements Model, PersistablePayload {
         processModel.setTempTradingPeerNodeAddress(proto.hasTempTradingPeerNodeAddress() ? NodeAddress.fromProto(proto.getTempTradingPeerNodeAddress()) : null);
         processModel.setMediatedPayoutTxSignature(ProtoUtil.byteArrayOrNullFromProto(proto.getMediatedPayoutTxSignature()));
         processModel.setMakerSignature(proto.getMakerSignature());
-        processModel.setArbitratorNodeAddress(proto.hasArbitratorNodeAddress() ? NodeAddress.fromProto(proto.getArbitratorNodeAddress()) : null);
+        processModel.setBackupArbitrator(proto.hasBackupArbitrator() ? NodeAddress.fromProto(proto.getBackupArbitrator()) : null);
         processModel.setPreparedMultisigHex(ProtoUtil.stringOrNullFromProto(proto.getPreparedMultisigHex()));
         processModel.setMadeMultisigHex(ProtoUtil.stringOrNullFromProto(proto.getMadeMultisigHex()));
         processModel.setMultisigSetupComplete(proto.getMultisigSetupComplete());

core/src/main/java/bisq/core/trade/protocol/SellerAsMakerProtocol.java

@@ -38,6 +38,7 @@ import bisq.core.trade.protocol.tasks.ProcessSignContractResponse;
 import bisq.core.trade.protocol.tasks.SendSignContractRequestAfterMultisig;
 import bisq.core.trade.protocol.tasks.TradeTask;
 import bisq.core.trade.protocol.tasks.maker.MakerRemovesOpenOffer;
+import bisq.core.trade.protocol.tasks.maker.MakerSendsInitTradeRequestIfUnreserved;
 import bisq.core.trade.protocol.tasks.maker.MakerVerifyTakerFeePayment;
 import bisq.core.trade.protocol.tasks.seller.SellerCreatesDelayedPayoutTx;
 import bisq.core.trade.protocol.tasks.seller.SellerSendDelayedPayoutTxSignatureRequest;
@@ -144,7 +145,7 @@ public class SellerAsMakerProtocol extends SellerProtocol implements MakerProtoc
                     ProcessInitTradeRequest.class,
                     //ApplyFilter.class, // TODO (woodser): these checks apply when maker signs availability request, but not here
                     //VerifyPeersAccountAgeWitness.class, // TODO (woodser): these checks apply after in multisig, means if rejected need to reimburse other's fee
-                    //MakerSendsInitTradeRequestIfUnreserved.class, // TODO (woodser): implement this
+                    MakerSendsInitTradeRequestIfUnreserved.class,
                     MakerRemovesOpenOffer.class).
                     using(new TradeTaskRunner(trade,
                             () -> {

core/src/main/java/bisq/core/trade/protocol/SellerAsTakerProtocol.java

@@ -73,6 +73,7 @@ public class SellerAsTakerProtocol extends SellerProtocol implements TakerProtoc
         super(trade);
         Offer offer = checkNotNull(trade.getOffer());
         trade.getTradingPeer().setPubKeyRing(offer.getPubKeyRing());
+        trade.setMakerPubKeyRing(offer.getPubKeyRing());
     }
 
 

core/src/main/java/bisq/core/trade/protocol/TradingPeer.java

@@ -27,7 +27,7 @@ import bisq.common.proto.persistable.PersistablePayload;
 
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Message;
-
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.stream.Collectors;
@@ -102,6 +102,8 @@ public final class TradingPeer implements PersistablePayload {
     @Nullable
     private String reserveTxKey;
     @Nullable
+    private List<String> reserveTxKeyImages = new ArrayList<>();
+    @Nullable
     private String preparedMultisigHex;
     @Nullable
     private String madeMultisigHex;
@@ -120,7 +122,8 @@ public final class TradingPeer implements PersistablePayload {
     @Override
     public Message toProtoMessage() {
         final protobuf.TradingPeer.Builder builder = protobuf.TradingPeer.newBuilder()
-                .setChangeOutputValue(changeOutputValue);
+                .setChangeOutputValue(changeOutputValue)
+                .addAllReserveTxKeyImages(reserveTxKeyImages);
         Optional.ofNullable(accountId).ifPresent(builder::setAccountId);
         Optional.ofNullable(paymentAccountId).ifPresent(builder::setPaymentAccountId);
         Optional.ofNullable(paymentMethodId).ifPresent(builder::setPaymentMethodId);
@@ -183,6 +186,7 @@ public final class TradingPeer implements PersistablePayload {
             tradingPeer.setReserveTxHash(ProtoUtil.stringOrNullFromProto(proto.getReserveTxHash()));
             tradingPeer.setReserveTxHex(ProtoUtil.stringOrNullFromProto(proto.getReserveTxHex()));
             tradingPeer.setReserveTxKey(ProtoUtil.stringOrNullFromProto(proto.getReserveTxKey()));
+            tradingPeer.setReserveTxKeyImages(proto.getReserveTxKeyImagesList());
             tradingPeer.setPreparedMultisigHex(ProtoUtil.stringOrNullFromProto(proto.getPreparedMultisigHex()));
             tradingPeer.setMadeMultisigHex(ProtoUtil.stringOrNullFromProto(proto.getMadeMultisigHex()));
             tradingPeer.setSignedPayoutTxHex(ProtoUtil.stringOrNullFromProto(proto.getSignedPayoutTxHex()));

core/src/main/java/bisq/core/trade/protocol/tasks/ArbitratorSendsInitMultisigRequestsIfFundsReserved.java

@@ -1,131 +0,0 @@
-/*
- * This file is part of Bisq.
- *
- * Bisq is free software: you can redistribute it and/or modify it
- * under the terms of the GNU Affero General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or (at
- * your option) any later version.
- *
- * Bisq is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
- * License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package bisq.core.trade.protocol.tasks;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import bisq.common.app.Version;
-import bisq.common.crypto.Sig;
-import bisq.common.taskrunner.TaskRunner;
-import bisq.core.payment.payload.PaymentAccountPayload;
-import bisq.core.trade.Trade;
-import bisq.core.trade.messages.InitMultisigRequest;
-import bisq.core.trade.messages.InitTradeRequest;
-import bisq.network.p2p.SendDirectMessageListener;
-import com.google.common.base.Charsets;
-import java.util.Date;
-import java.util.UUID;
-import lombok.extern.slf4j.Slf4j;
-import monero.wallet.MoneroWallet;
-
-/**
- * Arbitrator sends InitMultisigRequest to maker and taker if both reserve txs received.
- */
-@Slf4j
-public class ArbitratorSendsInitMultisigRequestsIfFundsReserved extends TradeTask {
-    
-    private boolean takerAck;
-    private boolean makerAck;
-    
-    @SuppressWarnings({"unused"})
-    public ArbitratorSendsInitMultisigRequestsIfFundsReserved(TaskRunner taskHandler, Trade trade) {
-        super(taskHandler, trade);
-    }
-
-    @Override
-    protected void run() {
-        try {
-            runInterceptHook();
-            
-            // skip if arbitrator does not have maker reserve tx
-            if (processModel.getMaker().getReserveTxHash() == null) {
-                log.info("Arbitrator does not have maker reserve tx for offerId {}, waiting to receive before initializing multisig wallet", processModel.getOffer().getId());
-                complete();
-                return;
-            }
-            
-            // create wallet for multisig
-            MoneroWallet multisigWallet = processModel.getXmrWalletService().createMultisigWallet(trade.getId());
-            
-            // prepare multisig
-            String preparedHex = multisigWallet.prepareMultisig();
-            processModel.setPreparedMultisigHex(preparedHex);
-
-            // create message to initialize multisig
-            InitMultisigRequest request = new InitMultisigRequest(
-                    processModel.getOffer().getId(),
-                    processModel.getMyNodeAddress(),
-                    processModel.getPubKeyRing(),
-                    UUID.randomUUID().toString(),
-                    Version.getP2PMessageVersion(),
-                    new Date().getTime(),
-                    preparedHex,
-                    null);
-
-            // send request to maker
-            log.info("Send {} with offerId {} and uid {} to maker {}", request.getClass().getSimpleName(), request.getTradeId(), request.getUid(), trade.getMakerNodeAddress());
-            processModel.getP2PService().sendEncryptedDirectMessage(
-                    trade.getMakerNodeAddress(),
-                    trade.getMakerPubKeyRing(),
-                    request,
-                    new SendDirectMessageListener() {
-                        @Override
-                        public void onArrived() {
-                            log.info("{} arrived at arbitrator: offerId={}; uid={}", request.getClass().getSimpleName(), request.getTradeId(), request.getUid());
-                            makerAck = true;
-                            checkComplete();
-                        }
-                        @Override
-                        public void onFault(String errorMessage) {
-                            log.error("Sending {} failed: uid={}; peer={}; error={}", request.getClass().getSimpleName(), request.getUid(), trade.getMakerNodeAddress(), errorMessage);
-                            appendToErrorMessage("Sending message failed: message=" + request + "\nerrorMessage=" + errorMessage);
-                            failed();
-                        }
-                    }
-            );
-
-            // send request to taker
-            log.info("Send {} with offerId {} and uid {} to taker {}", request.getClass().getSimpleName(), request.getTradeId(), request.getUid(), trade.getTakerNodeAddress());
-            processModel.getP2PService().sendEncryptedDirectMessage(
-                    trade.getTakerNodeAddress(),
-                    trade.getTakerPubKeyRing(),
-                    request,
-                    new SendDirectMessageListener() {
-                        @Override
-                        public void onArrived() {
-                            log.info("{} arrived at peer: offerId={}; uid={}", request.getClass().getSimpleName(), request.getTradeId(), request.getUid());
-                            takerAck = true;
-                            checkComplete();
-                        }
-                        @Override
-                        public void onFault(String errorMessage) {
-                            log.error("Sending {} failed: uid={}; peer={}; error={}", request.getClass().getSimpleName(), request.getUid(), trade.getTakerNodeAddress(), errorMessage);
-                            appendToErrorMessage("Sending message failed: message=" + request + "\nerrorMessage=" + errorMessage);
-                            failed();
-                        }
-                    }
-            );
-        } catch (Throwable t) {
-            failed(t);
-        }
-    }
-    
-    private void checkComplete() {
-        if (makerAck && takerAck) complete();
-    }
-}

core/src/main/java/bisq/core/trade/protocol/tasks/ArbitratorSendsInitTradeAndMultisigRequests.java

@@ -22,24 +22,33 @@ import bisq.common.app.Version;
 import bisq.common.crypto.Sig;
 import bisq.common.taskrunner.TaskRunner;
 import bisq.core.trade.Trade;
+import bisq.core.trade.messages.InitMultisigRequest;
 import bisq.core.trade.messages.InitTradeRequest;
 import bisq.core.trade.protocol.TradeListener;
 import bisq.network.p2p.AckMessage;
 import bisq.network.p2p.NodeAddress;
+import bisq.network.p2p.P2PService;
 import bisq.network.p2p.SendDirectMessageListener;
 import com.google.common.base.Charsets;
 import java.util.Date;
 import java.util.UUID;
 import lombok.extern.slf4j.Slf4j;
+import monero.wallet.MoneroWallet;
 
 /**
  * Arbitrator sends InitTradeRequest to maker after receiving InitTradeRequest
  * from taker and verifying taker reserve tx.
+ * 
+ * Arbitrator sends InitMultisigRequests after the maker acks.
  */
 @Slf4j
-public class ArbitratorSendsInitTradeRequestToMakerIfFromTaker extends TradeTask {
+public class ArbitratorSendsInitTradeAndMultisigRequests extends TradeTask {
+    
+    private boolean takerAck;
+    private boolean makerAck;
+    
     @SuppressWarnings({"unused"})
-    public ArbitratorSendsInitTradeRequestToMakerIfFromTaker(TaskRunner taskHandler, Trade trade) {
+    public ArbitratorSendsInitTradeAndMultisigRequests(TaskRunner taskHandler, Trade trade) {
         super(taskHandler, trade);
     }
 
@@ -48,12 +57,15 @@ public class ArbitratorSendsInitTradeRequestToMakerIfFromTaker extends TradeTask
         try {
             runInterceptHook();
             
-            // collect fields for request
+            // skip if request not from taker
-            String offerId = processModel.getOffer().getId();
             InitTradeRequest request = (InitTradeRequest) processModel.getTradeMessage();
+            if (!request.getSenderNodeAddress().equals(trade.getTakerNodeAddress())) {
+                complete();
+                return;
+            }
             
             // arbitrator signs offer id as nonce to avoid challenge protocol
-            byte[] sig = Sig.sign(processModel.getKeyRing().getSignatureKeyPair().getPrivate(), offerId.getBytes(Charsets.UTF_8));
+            byte[] sig = Sig.sign(processModel.getKeyRing().getSignatureKeyPair().getPrivate(), processModel.getOfferId().getBytes(Charsets.UTF_8));
             
             // save pub keys
             processModel.getArbitrator().setPubKeyRing(processModel.getPubKeyRing()); // TODO (woodser): why duplicating field in process model
@@ -63,7 +75,7 @@ public class ArbitratorSendsInitTradeRequestToMakerIfFromTaker extends TradeTask
             
             // create request to initialize trade with maker
             InitTradeRequest makerRequest = new InitTradeRequest(
-                    offerId,
+                    processModel.getOfferId(),
                     request.getSenderNodeAddress(),
                     request.getPubKeyRing(),
                     trade.getTradeAmount().value,
@@ -91,7 +103,7 @@ public class ArbitratorSendsInitTradeRequestToMakerIfFromTaker extends TradeTask
                 public void onAckMessage(AckMessage ackMessage, NodeAddress sender) {
                     if (sender.equals(trade.getMakerNodeAddress()) && ackMessage.getSourceMsgClassName().equals(InitTradeRequest.class.getSimpleName())) {
                         trade.removeListener(this);
-                        if (ackMessage.isSuccess()) complete();
+                        if (ackMessage.isSuccess()) sendInitMultisigRequests();
                         else failed("Received unsuccessful ack for InitTradeRequest from maker"); // TODO (woodser): maker should not do this, penalize them by broadcasting reserve tx?
                     }
                 }
@@ -122,4 +134,80 @@ public class ArbitratorSendsInitTradeRequestToMakerIfFromTaker extends TradeTask
             failed(t);
         }
     }
+    
+    private void sendInitMultisigRequests() {
+        
+        // ensure arbitrator has maker's reserve tx
+        if (processModel.getMaker().getReserveTxHash() == null) {
+            log.warn("Arbitrator {} does not have maker's reserve tx after initializing trade", P2PService.getMyNodeAddress());
+            failed();
+            return;
+        }
+        
+        // create wallet for multisig
+        MoneroWallet multisigWallet = processModel.getXmrWalletService().createMultisigWallet(trade.getId());
+        
+        // prepare multisig
+        String preparedHex = multisigWallet.prepareMultisig();
+        processModel.setPreparedMultisigHex(preparedHex);
+
+        // create message to initialize multisig
+        InitMultisigRequest initMultisigRequest = new InitMultisigRequest(
+                processModel.getOffer().getId(),
+                processModel.getMyNodeAddress(),
+                processModel.getPubKeyRing(),
+                UUID.randomUUID().toString(),
+                Version.getP2PMessageVersion(),
+                new Date().getTime(),
+                preparedHex,
+                null);
+
+        // send request to maker
+        log.info("Send {} with offerId {} and uid {} to maker {}", initMultisigRequest.getClass().getSimpleName(), initMultisigRequest.getTradeId(), initMultisigRequest.getUid(), trade.getMakerNodeAddress());
+        processModel.getP2PService().sendEncryptedDirectMessage(
+                trade.getMakerNodeAddress(),
+                trade.getMakerPubKeyRing(),
+                initMultisigRequest,
+                new SendDirectMessageListener() {
+                    @Override
+                    public void onArrived() {
+                        log.info("{} arrived at arbitrator: offerId={}; uid={}", initMultisigRequest.getClass().getSimpleName(), initMultisigRequest.getTradeId(), initMultisigRequest.getUid());
+                        makerAck = true;
+                        checkComplete();
+                    }
+                    @Override
+                    public void onFault(String errorMessage) {
+                        log.error("Sending {} failed: uid={}; peer={}; error={}", initMultisigRequest.getClass().getSimpleName(), initMultisigRequest.getUid(), trade.getMakerNodeAddress(), errorMessage);
+                        appendToErrorMessage("Sending message failed: message=" + initMultisigRequest + "\nerrorMessage=" + errorMessage);
+                        failed();
+                    }
+                }
+        );
+
+        // send request to taker
+        log.info("Send {} with offerId {} and uid {} to taker {}", initMultisigRequest.getClass().getSimpleName(), initMultisigRequest.getTradeId(), initMultisigRequest.getUid(), trade.getTakerNodeAddress());
+        processModel.getP2PService().sendEncryptedDirectMessage(
+                trade.getTakerNodeAddress(),
+                trade.getTakerPubKeyRing(),
+                initMultisigRequest,
+                new SendDirectMessageListener() {
+                    @Override
+                    public void onArrived() {
+                        log.info("{} arrived at peer: offerId={}; uid={}", initMultisigRequest.getClass().getSimpleName(), initMultisigRequest.getTradeId(), initMultisigRequest.getUid());
+                        takerAck = true;
+                        checkComplete();
+                    }
+                    @Override
+                    public void onFault(String errorMessage) {
+                        log.error("Sending {} failed: uid={}; peer={}; error={}", initMultisigRequest.getClass().getSimpleName(), initMultisigRequest.getUid(), trade.getTakerNodeAddress(), errorMessage);
+                        appendToErrorMessage("Sending message failed: message=" + initMultisigRequest + "\nerrorMessage=" + errorMessage);
+                        failed();
+                    }
+                }
+        );
+    }
+    
+    private void checkComplete() {
+        if (makerAck && takerAck) complete();
+    }
 }

core/src/main/java/bisq/core/trade/protocol/tasks/SendSignContractRequestAfterMultisig.java

@@ -23,7 +23,6 @@ import bisq.core.btc.model.XmrAddressEntry;
 import bisq.core.offer.Offer;
 import bisq.core.trade.MakerTrade;
 import bisq.core.trade.SellerTrade;
-import bisq.core.trade.TakerTrade;
 import bisq.core.trade.Trade;
 import bisq.core.trade.TradeUtils;
 import bisq.core.trade.messages.SignContractRequest;
@@ -62,8 +61,8 @@ public class SendSignContractRequestAfterMultisig extends TradeTask {
 
           // thaw reserved outputs
           MoneroWallet wallet = trade.getXmrWalletService().getWallet();
-          for (String frozenKeyImage : processModel.getFrozenKeyImages()) {
+          for (String reserveTxKeyImage : trade.getSelf().getReserveTxKeyImages()) {
-              wallet.thawOutput(frozenKeyImage);
+              wallet.thawOutput(reserveTxKeyImage);
           }
           
           // create deposit tx

core/src/main/java/bisq/core/trade/protocol/tasks/UpdateMultisigWithTradingPeer.java

@@ -101,8 +101,7 @@ public class UpdateMultisigWithTradingPeer extends TradeTask {
                     new Date().getTime(),
                     updatedMultisigHex);
 
-            System.out.println("SENDING MESSAGE!!!!!!!");
+            System.out.println("Sending message: " + message);
-            System.out.println(message);
 
             // TODO (woodser): trade.getTradingPeerNodeAddress() and/or trade.getTradingPeerPubKeyRing() are null on restart of application, so cannot send payment to complete trade
             log.info("Send {} with offerId {} and uid {} to peer {}", message.getClass().getSimpleName(), message.getTradeId(), message.getUid(), trade.getTradingPeerNodeAddress());

core/src/main/java/bisq/core/trade/protocol/tasks/maker/MakerSendsInitTradeRequestIfUnreserved.java

@@ -18,14 +18,11 @@
 package bisq.core.trade.protocol.tasks.maker;
 
 import bisq.core.btc.model.XmrAddressEntry;
-import bisq.core.btc.wallet.XmrWalletService;
+import bisq.core.offer.Offer;
-import bisq.core.payment.payload.PaymentAccountPayload;
 import bisq.core.trade.Trade;
 import bisq.core.trade.messages.InitTradeRequest;
 import bisq.core.trade.protocol.tasks.TradeTask;
-import bisq.core.user.User;
 
-import bisq.network.p2p.NodeAddress;
 import bisq.network.p2p.SendDirectMessageListener;
 
 import bisq.common.app.Version;
@@ -34,8 +31,6 @@ import bisq.common.taskrunner.TaskRunner;
 
 import com.google.common.base.Charsets;
 
-import java.util.Date;
-import java.util.List;
 import java.util.UUID;
 
 import lombok.extern.slf4j.Slf4j;
@@ -55,88 +50,63 @@ public class MakerSendsInitTradeRequestIfUnreserved extends TradeTask {
         try {
             runInterceptHook();
 
-            System.out.println("MAKER SENDING INIT TRADE REQ TO ARBITRATOR");
+            // skip if arbitrator is signer and therefore already has reserve tx
+            Offer offer = processModel.getOffer();
+            if (offer.getOfferPayload().getArbitratorSigner().equals(trade.getArbitratorNodeAddress())) {
+                complete();
+                return;
+            }
 
             // verify trade
-            InitTradeRequest request = (InitTradeRequest) processModel.getTradeMessage();
+            InitTradeRequest makerRequest = (InitTradeRequest) processModel.getTradeMessage(); // arbitrator's InitTradeRequest to maker
-            checkNotNull(request);
+            checkNotNull(makerRequest);
-            checkTradeId(processModel.getOfferId(), request);
+            checkTradeId(processModel.getOfferId(), makerRequest);
-
-            // collect fields to send taker prepared multisig response  // TODO (woodser): this should happen on response from arbitrator
-            XmrWalletService walletService = processModel.getProvider().getXmrWalletService();
-            String offerId = processModel.getOffer().getId();
-            String payoutAddress = walletService.getWallet().createSubaddress(0).getAddress();  // TODO (woodser): register TRADE_PAYOUT?
-            walletService.getWallet().save();
-            checkNotNull(trade.getTradeAmount(), "TradeAmount must not be null");
-//            checkNotNull(trade.getTakerFeeTxId(), "TakeOfferFeeTxId must not be null"); // TODO (woodser): no taker fee tx yet if creating multisig first
-            final User user = processModel.getUser();
-            checkNotNull(user, "User must not be null");
-            final List<NodeAddress> acceptedMediatorAddresses = user.getAcceptedMediatorAddresses();
-            checkNotNull(acceptedMediatorAddresses, "acceptedMediatorAddresses must not be null");
             
-            // maker signs offer id as nonce to avoid challenge protocol
+            // maker signs offer id as nonce to avoid challenge protocol // TODO (woodser): is this necessary?
-            final PaymentAccountPayload paymentAccountPayload = checkNotNull(processModel.getPaymentAccountPayload(trade), "processModel.getPaymentAccountPayload(trade) must not be null");
+            byte[] sig = Sig.sign(processModel.getKeyRing().getSignatureKeyPair().getPrivate(), offer.getId().getBytes(Charsets.UTF_8));
-            byte[] sig = Sig.sign(processModel.getKeyRing().getSignatureKeyPair().getPrivate(), offerId.getBytes(Charsets.UTF_8));
-
-            System.out.println("MAKER SENDING ARBITRTATOR SENDER NODE ADDRESS");
-            System.out.println(processModel.getMyNodeAddress());
             
-            if (true) throw new RuntimeException("Not yet implemented");
+            // create request to arbitrator
-            
+            InitTradeRequest arbitratorRequest = new InitTradeRequest(
-            // create message to initialize trade
+                    offer.getId(),
-            InitTradeRequest message = new InitTradeRequest(
-                    offerId,
                     processModel.getMyNodeAddress(),
                     processModel.getPubKeyRing(),
-                    trade.getTradeAmount().value,
+                    offer.getAmount().value,
-                    trade.getTradePrice().getValue(),
+                    offer.getPrice().getValue(),
-                    trade.getTakerFee().getValue(),
+                    offer.getMakerFee().value,
-                    processModel.getAccountId(),
+                    trade.getProcessModel().getAccountId(),
-                    paymentAccountPayload.getId(),
+                    offer.getMakerPaymentAccountId(),
-                    paymentAccountPayload.getPaymentMethodId(),
+                    offer.getOfferPayload().getPaymentMethodId(),
                     UUID.randomUUID().toString(),
                     Version.getP2PMessageVersion(),
                     sig,
-                    new Date().getTime(),
+                    makerRequest.getCurrentDate(),
                     trade.getMakerNodeAddress(),
                     trade.getTakerNodeAddress(),
                     trade.getArbitratorNodeAddress(),
-                    processModel.getReserveTx().getHash(), // TODO (woodser): need to first create and save reserve tx
+                    trade.getSelf().getReserveTxHash(),
-                    processModel.getReserveTx().getFullHex(),
+                    trade.getSelf().getReserveTxHex(),
-                    processModel.getReserveTx().getKey(),
+                    trade.getSelf().getReserveTxKey(),
-                    processModel.getXmrWalletService().getAddressEntry(offerId, XmrAddressEntry.Context.TRADE_PAYOUT).get().getAddressString(),
+                    model.getXmrWalletService().getOrCreateAddressEntry(offer.getId(), XmrAddressEntry.Context.TRADE_PAYOUT).getAddressString(),
                     null);
-
+            
-            log.info("Send {} with offerId {} and uid {} to peer {}",
-                    message.getClass().getSimpleName(), message.getTradeId(),
-                    message.getUid(), trade.getArbitratorNodeAddress());
-
-
-            System.out.println("MAKER TRADE INFO");
-            System.out.println("Trading peer node address: " + trade.getTradingPeerNodeAddress());
-            System.out.println("Maker node address: " + trade.getMakerNodeAddress());
-            System.out.println("Taker node adddress: " + trade.getTakerNodeAddress());
-            System.out.println("Arbitrator node address: " + trade.getArbitratorNodeAddress());
-
             // send request to arbitrator
+            log.info("Sending {} with offerId {} and uid {} to arbitrator {} with pub key ring {}", arbitratorRequest.getClass().getSimpleName(), arbitratorRequest.getTradeId(), arbitratorRequest.getUid(), trade.getArbitratorNodeAddress(), trade.getArbitratorPubKeyRing());
             processModel.getP2PService().sendEncryptedDirectMessage(
                     trade.getArbitratorNodeAddress(),
                     trade.getArbitratorPubKeyRing(),
-                    message,
+                    arbitratorRequest,
                     new SendDirectMessageListener() {
                         @Override
                         public void onArrived() {
-                            log.info("{} arrived at arbitrator: offerId={}; uid={}", message.getClass().getSimpleName(), message.getTradeId(), message.getUid());
+                            log.info("{} arrived at arbitrator: offerId={}", InitTradeRequest.class.getSimpleName(), trade.getId());
                             complete();
                         }
                         @Override
                         public void onFault(String errorMessage) {
-                            log.error("Sending {} failed: uid={}; peer={}; error={}", message.getClass().getSimpleName(), message.getUid(), trade.getTradingPeerNodeAddress(), errorMessage);
+                            log.warn("Failed to send {} to arbitrator, error={}.", InitTradeRequest.class.getSimpleName(), errorMessage);
-                            appendToErrorMessage("Sending message failed: message=" + message + "\nerrorMessage=" + errorMessage);
                             failed();
                         }
-                    }
+                    });
-            );
         } catch (Throwable t) {
             failed(t);
         }

core/src/main/java/bisq/core/trade/protocol/tasks/taker/TakerReservesTradeFunds.java

@@ -49,19 +49,18 @@ public class TakerReservesTradeFunds extends TradeTask {
             
             // freeze trade funds
             // TODO (woodser): synchronize to handle potential race condition where concurrent trades freeze each other's outputs
-            List<String> frozenKeyImages = new ArrayList<String>();
+            List<String> reserveTxKeyImages = new ArrayList<String>();
             MoneroWallet wallet = model.getXmrWalletService().getWallet();
             for (MoneroOutput input : reserveTx.getInputs()) {
-                frozenKeyImages.add(input.getKeyImage().getHex());
+                reserveTxKeyImages.add(input.getKeyImage().getHex());
                 wallet.freezeOutput(input.getKeyImage().getHex());
             }
             
             // save process state
             // TODO (woodser): persist
             processModel.setReserveTx(reserveTx);
-            processModel.setReserveTxHash(reserveTx.getHash());
+            processModel.getTaker().setReserveTxKeyImages(reserveTxKeyImages);
-            processModel.setFrozenKeyImages(frozenKeyImages);
+            trade.setTakerFeeTxId(reserveTx.getHash()); // TODO (woodser): this should be multisig deposit tx id? how is it used?
-            trade.setTakerFeeTxId(reserveTx.getHash());
             //trade.setState(Trade.State.TAKER_PUBLISHED_TAKER_FEE_TX); // TODO (woodser): fee tx is not broadcast separate, update states
             complete();
         } catch (Throwable t) {

core/src/main/java/bisq/core/trade/protocol/tasks/taker/TakerSendsInitTradeRequestToArbitrator.java

@@ -21,7 +21,7 @@ import bisq.core.support.dispute.mediation.mediator.Mediator;
 import bisq.core.trade.Trade;
 import bisq.core.trade.messages.InitTradeRequest;
 import bisq.core.trade.protocol.tasks.TradeTask;
-
+import bisq.network.p2p.NodeAddress;
 import bisq.network.p2p.SendDirectMessageListener;
 
 import bisq.common.app.Version;
@@ -42,62 +42,85 @@ public class TakerSendsInitTradeRequestToArbitrator extends TradeTask {
         try {
             runInterceptHook();
             
-            // get primary arbitrator
+            // send request to offer signer
-            Mediator arbitrator = processModel.getUser().getAcceptedMediatorByAddress(trade.getArbitratorNodeAddress());
+            sendInitTradeRequest(trade.getOffer().getOfferPayload().getArbitratorSigner(), new SendDirectMessageListener() {
-            if (arbitrator == null) throw new RuntimeException("Cannot get arbitrator instance from node address"); // TODO (woodser): null if arbitrator goes offline or never seen?
+                @Override
-            
+                public void onArrived() {
-            // save pub keys
+                    log.info("{} arrived at arbitrator: offerId={}", InitTradeRequest.class.getSimpleName(), trade.getId());
-            processModel.getArbitrator().setPubKeyRing(arbitrator.getPubKeyRing());
+                    complete();
-            trade.setArbitratorPubKeyRing(processModel.getArbitrator().getPubKeyRing());
+                }
-            trade.setMakerPubKeyRing(trade.getTradingPeer().getPubKeyRing());
+                
-            
+                // send request to backup arbitrator if signer unavailable
-            // send trade request to arbitrator
+                @Override
-            InitTradeRequest makerRequest = (InitTradeRequest) processModel.getTradeMessage();
+                public void onFault(String errorMessage) {
-            InitTradeRequest arbitratorRequest = new InitTradeRequest(
+                    log.info("Sending {} to signing arbitrator {} failed, using backup arbitrator {}. error={}", InitTradeRequest.class.getSimpleName(), trade.getOffer().getOfferPayload().getArbitratorSigner(), processModel.getBackupArbitrator(), errorMessage);
-                    makerRequest.getTradeId(),
+                    if (processModel.getBackupArbitrator() == null) {
-                    makerRequest.getSenderNodeAddress(),
+                        log.warn("Cannot take offer because signing arbitrator is offline and backup arbitrator is null");
-                    makerRequest.getPubKeyRing(),
+                        failed();
-                    makerRequest.getTradeAmount(),
+                        return;
-                    makerRequest.getTradePrice(),
+                    }
-                    makerRequest.getTradeFee(),
+                    sendInitTradeRequest(processModel.getBackupArbitrator(), new SendDirectMessageListener() {
-                    makerRequest.getAccountId(),
-                    makerRequest.getPaymentAccountId(),
-                    makerRequest.getPaymentMethodId(),
-                    makerRequest.getUid(),
-                    Version.getP2PMessageVersion(),
-                    makerRequest.getAccountAgeWitnessSignatureOfOfferId(),
-                    makerRequest.getCurrentDate(),
-                    makerRequest.getMakerNodeAddress(),
-                    makerRequest.getTakerNodeAddress(),
-                    trade.getArbitratorNodeAddress(),
-                    processModel.getReserveTx().getHash(),
-                    processModel.getReserveTx().getFullHex(),
-                    processModel.getReserveTx().getKey(),
-                    makerRequest.getPayoutAddress(),
-                    processModel.getMakerSignature());
-
-            // send request to arbitrator
-            System.out.println("SENDING INIT TRADE REQUEST TO ARBITRATOR!");
-            log.info("Send {} with offerId {} and uid {} to arbitrator {} with pub key ring", arbitratorRequest.getClass().getSimpleName(), arbitratorRequest.getTradeId(), arbitratorRequest.getUid(), trade.getArbitratorNodeAddress(), trade.getArbitratorPubKeyRing());
-            processModel.getP2PService().sendEncryptedDirectMessage(
-                    trade.getArbitratorNodeAddress(),
-                    trade.getArbitratorPubKeyRing(),
-                    arbitratorRequest,
-                    new SendDirectMessageListener() {
                         @Override
                         public void onArrived() {
-                            log.info("{} arrived at arbitrator: offerId={}; uid={}", arbitratorRequest.getClass().getSimpleName(), arbitratorRequest.getTradeId(), arbitratorRequest.getUid());
+                            log.info("{} arrived at backup arbitrator: offerId={}", InitTradeRequest.class.getSimpleName(), trade.getId());
+                            complete();
                         }
-                        @Override // TODO (woodser): handle case where primary arbitrator is unavailable so use backup arbitrator, distinguish offline from bad ack
+                        @Override
-                        public void onFault(String errorMessage) {
+                        public void onFault(String errorMessage) { // TODO (woodser): distinguish nack from offline
-                            log.error("Sending {} failed: uid={}; peer={}; error={}", arbitratorRequest.getClass().getSimpleName(), arbitratorRequest.getUid(), trade.getArbitratorNodeAddress(), errorMessage);
+                            log.warn("Cannot take offer because arbitrators are unavailable: error={}.", InitTradeRequest.class.getSimpleName(), errorMessage);
-                            appendToErrorMessage("Sending message failed: message=" + arbitratorRequest + "\nerrorMessage=" + errorMessage);
                             failed();
                         }
-                    }
+                    });
-            );
+                }
+            });
         } catch (Throwable t) {
           failed(t);
         }
     }
+    
+    private void sendInitTradeRequest(NodeAddress arbitratorNodeAddress, SendDirectMessageListener listener) {
+        
+        // get registered arbitrator
+        Mediator arbitrator = processModel.getUser().getAcceptedMediatorByAddress(arbitratorNodeAddress);
+        if (arbitrator == null) throw new RuntimeException("Node address " + arbitratorNodeAddress + " is not a registered arbitrator");
+        
+        // set pub keys
+        processModel.getArbitrator().setPubKeyRing(arbitrator.getPubKeyRing());
+        trade.setArbitratorNodeAddress(arbitratorNodeAddress);
+        trade.setArbitratorPubKeyRing(processModel.getArbitrator().getPubKeyRing());
+        
+        // create request to arbitrator
+        InitTradeRequest makerRequest = (InitTradeRequest) processModel.getTradeMessage(); // taker's InitTradeRequest to maker
+        InitTradeRequest arbitratorRequest = new InitTradeRequest(
+                makerRequest.getTradeId(),
+                makerRequest.getSenderNodeAddress(),
+                makerRequest.getPubKeyRing(),
+                makerRequest.getTradeAmount(),
+                makerRequest.getTradePrice(),
+                makerRequest.getTradeFee(),
+                makerRequest.getAccountId(),
+                makerRequest.getPaymentAccountId(),
+                makerRequest.getPaymentMethodId(),
+                makerRequest.getUid(),
+                Version.getP2PMessageVersion(),
+                makerRequest.getAccountAgeWitnessSignatureOfOfferId(),
+                makerRequest.getCurrentDate(),
+                makerRequest.getMakerNodeAddress(),
+                makerRequest.getTakerNodeAddress(),
+                trade.getArbitratorNodeAddress(),
+                processModel.getReserveTx().getHash(),
+                processModel.getReserveTx().getFullHex(),
+                processModel.getReserveTx().getKey(),
+                makerRequest.getPayoutAddress(),
+                processModel.getMakerSignature());
+
+        // send request to arbitrator
+        log.info("Sending {} with offerId {} and uid {} to arbitrator {} with pub key ring {}", arbitratorRequest.getClass().getSimpleName(), arbitratorRequest.getTradeId(), arbitratorRequest.getUid(), trade.getArbitratorNodeAddress(), trade.getArbitratorPubKeyRing());
+        processModel.getP2PService().sendEncryptedDirectMessage(
+                arbitratorNodeAddress,
+                arbitrator.getPubKeyRing(),
+                arbitratorRequest,
+                listener
+        );
+    }
 }

core/src/test/java/bisq/core/trade/TradableListTest.java

@@ -39,7 +39,7 @@ public class TradableListTest {
 
         // test adding an OpenOffer and convert toProto
         Offer offer = new Offer(offerPayload);
-        OpenOffer openOffer = new OpenOffer(offer);
+        OpenOffer openOffer = new OpenOffer(offer, 0, "", "", "");
         openOfferTradableList.add(openOffer);
         message = (protobuf.PersistableEnvelope) openOfferTradableList.toProtoMessage();
         assertEquals(message.getMessageCase(), TRADABLE_LIST);

desktop/src/main/java/bisq/desktop/main/portfolio/editoffer/EditOfferDataModel.java

@@ -219,7 +219,7 @@ class EditOfferDataModel extends MutableOfferDataModel {
                 offerPayload.getHashOfChallenge(),
                 offerPayload.getExtraDataMap(),
                 offerPayload.getProtocolVersion(),
-                offerPayload.getArbitratorNodeAddress(),
+                offerPayload.getArbitratorSigner(),
                 offerPayload.getArbitratorSignature(),
                 offerPayload.getReserveTxKeyImages());
 

proto/src/main/proto/pb.proto

@@ -189,7 +189,7 @@ message OfferAvailabilityResponse {
     repeated int32 supported_capabilities = 3;
     string uid = 4;
     string maker_signature = 5;
-    NodeAddress arbitrator_node_address = 6;
+    NodeAddress backup_arbitrator = 6;
 }
 
 message RefreshOfferMessage {
@@ -853,7 +853,7 @@ message OfferPayload {
     map<string, string> extra_data = 34;
     int32 protocol_version = 35;
 
-    NodeAddress arbitrator_node_address = 1001;
+    NodeAddress arbitrator_signer = 1001;
     string arbitrator_signature = 1002;
     repeated string reserve_tx_key_images = 1003;
 }
@@ -1472,9 +1472,11 @@ message OpenOffer {
 
     Offer offer = 1;
     State state = 2;
-    NodeAddress arbitrator_node_address = 3;
+    NodeAddress backup_arbitrator = 3;
     int64 trigger_price = 4;
-    repeated string frozen_key_images = 5;
+    string reserve_tx_hash = 5;
+    string reserve_tx_hex = 6;
+    string reserve_tx_key = 7;
 }
 
 message Tradable {
@@ -1644,18 +1646,16 @@ message ProcessModel {
     int64 seller_payout_amount_from_mediation = 20;
 
     string maker_signature = 1001;
-    NodeAddress arbitrator_node_address = 1002;
+    NodeAddress backup_arbitrator = 1002;
     TradingPeer maker = 1003;
     TradingPeer taker = 1004;
     TradingPeer arbitrator = 1005;
     NodeAddress temp_trading_peer_node_address = 1006;
-    string reserve_tx_hash = 1007;
+    string prepared_multisig_hex = 1007;
-    repeated string frozen_key_images = 1008;
+    string made_multisig_hex = 1008;
-    string prepared_multisig_hex = 1009;
+    bool multisig_setup_complete = 1009;
-    string made_multisig_hex = 1010;
+    bool maker_ready_to_fund_multisig = 1010;
-    bool multisig_setup_complete = 1011;
+    bool multisig_deposit_initiated = 1011;
-    bool maker_ready_to_fund_multisig = 1012;
-    bool multisig_deposit_initiated = 1013;
 }
 
 message TradingPeer {
@@ -1681,12 +1681,13 @@ message TradingPeer {
     string reserve_tx_hash = 1001;
     string reserve_tx_hex = 1002;
     string reserve_tx_key = 1003;
-    string prepared_multisig_hex = 1004;
+    repeated string reserve_tx_key_images = 1004;
-    string made_multisig_hex = 1005;
+    string prepared_multisig_hex = 1005;
-    string signed_payout_tx_hex = 1006;
+    string made_multisig_hex = 1006;
-    string deposit_tx_hash = 1007;
+    string signed_payout_tx_hex = 1007;
-    string deposit_tx_hex = 1008;
+    string deposit_tx_hash = 1008;
-    string deposit_tx_key = 1009;
+    string deposit_tx_hex = 1009;
+    string deposit_tx_key = 1010;
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////