[feat] use device keys for server login

apps/desktop/src/gui/application/gui_application.cpp

@@ -2983,6 +2983,7 @@ bool GuiApplication::RequestPasswordChange(const std::string &password) {
     password_change_result_ready_ = false;
     password_change_succeeded_ = false;
     password_change_result_uncertain_ = false;
+    password_change_recovery_ = false;
     password_change_requested_at_ = std::chrono::steady_clock::now();
     pending_password_change_request_id_ = request_id;
     pending_local_password_ = password;
@@ -3062,6 +3063,7 @@ void GuiApplication::HandlePasswordChangeResult() {
     password_change_result_ready_ = false;
     password_change_succeeded_ = false;
     password_change_result_uncertain_ = false;
+    password_change_recovery_ = false;
     pending_password_change_request_id_.clear();
     pending_local_password_.clear();
     password_change_error_.clear();
@@ -3108,23 +3110,53 @@ void GuiApplication::HandlePasswordChangeResult() {
 }
 
 void GuiApplication::HandleCredentialRecovery() {
-  bool retry_active = false;
-  bool promote_pending = false;
-  bool clear_pending = false;
+  CredentialRecoveryAction action;
   {
     std::lock_guard<std::mutex> lock(password_change_mutex_);
-    retry_active = credential_recovery_retry_active_;
-    promote_pending = credential_recovery_promote_pending_;
-    clear_pending = credential_recovery_clear_pending_;
-    credential_recovery_retry_active_ = false;
-    credential_recovery_promote_pending_ = false;
-    credential_recovery_clear_pending_ = false;
-    if (retry_active) {
+    action = std::exchange(credential_recovery_action_, CredentialRecoveryAction::None);
+    if (action == CredentialRecoveryAction::RetryActive) {
       credential_recovery_attempt_pending_ = false;
     }
   }
 
-  if (retry_active) {
+  if (action == CredentialRecoveryAction::ResumePending) {
+    // Key authentication proves device ownership, not which password committed.
+    // Replay the durable request and promote only its successful server reply.
+    const bool self_hosted = config_center_->IsSelfHosted();
+    std::string request_id;
+    const auto identity = settings_.PendingPasswordChangeIdentity(self_hosted,
+        self_hosted ? config_center_->GetSignalServerHost() : config_center_->GetDefaultServerHost(),
+        self_hosted ? config_center_->GetSignalServerPort() : config_center_->GetDefaultSignalServerPort(),
+        &request_id);
+    const auto at = identity.find('@');
+    if (!peer_ || !signal_connected_ || at == std::string::npos || request_id.empty() ||
+        identity.substr(0, at) != client_id_) return;
+    const auto password = identity.substr(at + 1);
+    {
+      std::lock_guard lock(password_change_mutex_);
+      if (password_change_pending_) return;
+      password_change_pending_ = true;
+      password_change_result_ready_ = false;
+      password_change_succeeded_ = false;
+      password_change_result_uncertain_ = false;
+      password_change_recovery_ = true;
+      password_change_requested_at_ = std::chrono::steady_clock::now();
+      pending_password_change_request_id_ = request_id;
+      pending_local_password_ = password;
+      password_change_error_.clear();
+    }
+    const auto message = nlohmann::json{{"type", "change_password"},
+        {"request_id", request_id}, {"new_password", password}}.dump();
+    if (SendSignalMessage(peer_, message.data(), message.size()) != 0) {
+      std::lock_guard lock(password_change_mutex_);
+      password_change_result_ready_ = true;
+      password_change_result_uncertain_ = true;
+      password_change_error_ = "Password recovery connection unavailable";
+    }
+    return;
+  }
+
+  if (action == CredentialRecoveryAction::RetryActive) {
     LOG_INFO("Pending credential was not accepted; retrying active credential");
     if (peer_) {
       CloseConnectionPeer();
@@ -3132,7 +3164,7 @@ void GuiApplication::HandleCredentialRecovery() {
     return;
   }
 
-  if (promote_pending) {
+  if (action == CredentialRecoveryAction::PromotePending) {
 #if defined(__linux__) && !defined(__OHOS__)
     HeadlessConsole::Instance().NotifyKey("console_password_recovered");
 #endif
@@ -3141,7 +3173,7 @@ void GuiApplication::HandleCredentialRecovery() {
     } else {
       LOG_INFO("Recovered password change with pending credential");
     }
-  } else if (clear_pending) {
+  } else if (action == CredentialRecoveryAction::ClearPending) {
 #if defined(__linux__) && !defined(__OHOS__)
     HeadlessConsole::Instance().NotifyKey("console_password_retained");
 #endif

apps/desktop/src/gui/features/settings/settings_manager.cpp

@@ -593,14 +593,17 @@ bool SettingsManager::StagePendingPasswordChange(
 }
 
 std::string SettingsManager::PendingPasswordChangeIdentity(
-    bool self_hosted, const std::string &server_host, int server_port) const {
+    bool self_hosted, const std::string &server_host, int server_port,
+    std::string* request_id) const {
   std::lock_guard<std::mutex> lock(cache_mutex_);
+  if (request_id) request_id->clear();
   if (cache_v3_.pending_identity[0] == '\0' ||
       cache_v3_.pending_self_hosted != self_hosted ||
       cache_v3_.pending_server_port != server_port ||
       server_host != cache_v3_.pending_server_host) {
     return {};
   }
+  if (request_id) *request_id = cache_v3_.pending_request_id;
   return cache_v3_.pending_identity;
 }
 

apps/desktop/src/gui/features/settings/settings_manager.h

@@ -51,7 +51,7 @@ public:
                                   const std::string &request_id);
   std::string PendingPasswordChangeIdentity(
       bool self_hosted, const std::string &server_host,
-      int server_port) const;
+      int server_port, std::string* request_id = nullptr) const;
   bool PromotePendingPasswordChange();
   bool ClearPendingPasswordChange();
 

apps/desktop/src/gui/runtime/connection_runtime.cpp

@@ -709,6 +709,7 @@ int GuiRuntime::ConnectTo(const std::string& remote_id, const char* password,
         props->audio_capture_button_pressed_ = !background;
         memcpy(&props->params_, &params_, sizeof(Params));
         props->params_.user_id = props->local_id_.c_str();
+        props->params_.on_signal_exchange = nullptr;
         props->peer_events_ = std::make_shared<PeerEventHandler>(*this);
         props->params_.user_data = props->peer_events_.get();
         props->peer_ = CreatePeer(&props->params_);

apps/desktop/src/gui/runtime/device_identity_store.h

@@ -13,7 +13,7 @@
 
 namespace crossdesk::device_identity_store {
 
-// The trusted-device pairing key lives in cache/identity.json. Read the latest
+// The shared device signing key lives in cache/identity.json. Read the latest
 // document under a process lock, apply an update, then atomically persist it.
 // Throw on corruption, unsafe permissions, lock contention or persistence error.
 void Update(const std::filesystem::path& cache,

apps/desktop/src/gui/runtime/device_login.cpp

@@ -0,0 +1,71 @@
+#include "runtime/device_login.h"
+
+#include <algorithm>
+#include <cstring>
+
+#include "runtime/trusted_devices.h"
+
+namespace crossdesk {
+int DeviceLogin::Exchange(SignalExchangeStage stage, const nlohmann::json& message,
+    const TrustedDevices* identity, char* response, size_t capacity) {
+  auto output = [&](const nlohmann::json& reply) {
+    const auto text = reply.dump();
+    if (text.empty() || text.size() > capacity) return -1;
+    std::memcpy(response, text.data(), text.size());
+    return static_cast<int>(text.size());
+  };
+  if (stage == SignalExchangeStage::PrepareLogin) {
+    phase_ = Phase::Idle;
+    used_password_ = false;
+    password_.clear();
+    request_ = message;
+    const auto login = message.at("user_id").get<std::string>();
+    if (login.rfind("C-", 0) == 0) return 0;
+    if (!identity) return -1;  // Never fall back when local key storage fails.
+    const auto at = login.find('@');
+    request_["user_id"] = login.substr(0, at);
+    if (at != std::string::npos) password_ = login.substr(at + 1);
+    request_["device_key"] = {{"version", 1}, {"public_key", identity->PublicKey()}};
+    request_.erase("reconnect_token");
+    request_.erase("reconnect_version");
+    phase_ = Phase::AwaitingChallenge;
+    return output(request_);
+  }
+  if (!Pending()) return 0;
+  const auto type = message.value("type", "");
+  if (type == "login_challenge") {
+    if (!identity || phase_ != Phase::AwaitingChallenge || message.at("device_key_version") != 1 ||
+        message.at("user_id") != request_.at("user_id")) return -1;
+    const auto nonce = message.at("nonce").get<std::string>();
+    if (nonce.size() != 64 || !std::all_of(nonce.begin(), nonce.end(),
+        [](char c) { return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f'); }))
+      return -1;
+    const auto id = request_.at("user_id").get<std::string>();
+    auto reply = request_;
+    used_password_ = message.at("password_required").get<bool>();
+    if (used_password_) {
+      if (id.empty() || password_.empty()) return -1;
+      reply["user_id"] = id + "@" + password_;
+    }
+    const auto transcript = nlohmann::json::array(
+        {"crossdesk.device-login.v1", id, identity->PublicKey(), nonce}).dump();
+    reply["device_key"]["nonce"] = nonce;
+    reply["device_key"]["signature"] = identity->Sign(transcript);
+    phase_ = Phase::AwaitingResult;
+    password_.clear();
+    return output(reply);
+  }
+  if (type == "login") {
+    if (message.at("status") == "success") {
+      if (phase_ != Phase::AwaitingResult || message.value("device_key_version", 0) != 1) return -1;
+      const auto assigned = message.at("user_id").get<std::string>();
+      const auto expected = request_.at("user_id").get<std::string>();
+      if (assigned.empty() || (!expected.empty() && assigned != expected)) return -1;
+    }
+    password_.clear();
+    request_.clear();
+    phase_ = Phase::Idle;
+  }
+  return 0;
+}
+}  // namespace crossdesk

apps/desktop/src/gui/runtime/device_login.h

@@ -0,0 +1,35 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-11-02
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _DEVICE_LOGIN_H_
+#define _DEVICE_LOGIN_H_
+
+#include <nlohmann/json.hpp>
+#include <string>
+
+#include "minirtc.h"
+
+namespace crossdesk {
+class TrustedDevices;
+
+// One signaling connection's application authentication, owned by its callbacks.
+class DeviceLogin {
+ public:
+  int Exchange(SignalExchangeStage stage, const nlohmann::json& message,
+               const TrustedDevices* identity, char* response, size_t capacity);
+  bool Pending() const { return phase_ != Phase::Idle; }
+  bool UsedPassword() const { return used_password_; }
+
+ private:
+  enum class Phase { Idle, AwaitingChallenge, AwaitingResult };
+  nlohmann::json request_;
+  std::string password_;
+  Phase phase_ = Phase::Idle;
+  bool used_password_ = false;
+};
+}  // namespace crossdesk
+
+#endif

apps/desktop/src/gui/runtime/gui_runtime.cpp

@@ -190,9 +190,7 @@ int GuiRuntime::CreateConnectionPeer() {
     if (pending_identity.empty()) {
       credential_recovery_in_progress_ = false;
       credential_recovery_attempt_pending_ = false;
-      credential_recovery_retry_active_ = false;
-      credential_recovery_promote_pending_ = false;
-      credential_recovery_clear_pending_ = false;
+      credential_recovery_action_ = CredentialRecoveryAction::None;
     } else if (!credential_recovery_in_progress_) {
       credential_recovery_in_progress_ = true;
       credential_recovery_attempt_pending_ = true;
@@ -270,6 +268,7 @@ int GuiRuntime::CreateConnectionPeer() {
 
   params_.on_signal_status = PeerEventHandler::OnSignalStatus;
   params_.on_signal_message = PeerEventHandler::OnSignalMessage;
+  params_.on_signal_exchange = PeerEventHandler::OnSignalExchange;
   params_.on_connection_status = PeerEventHandler::OnConnectionStatus;
   params_.on_net_status_report = PeerEventHandler::OnNetStatusReport;
 

apps/desktop/src/gui/runtime/peer_event_handler.cpp

@@ -84,6 +84,24 @@ PeerEventHandler::PeerEventHandler(GuiRuntime& owner) : owner_(owner) {
   owner_.transfers_.Connected(this, "");
 }
 
+int PeerEventHandler::OnSignalExchange(SignalExchangeStage stage, const char* message,
+    size_t size, char* response, size_t capacity, void* user_data) {
+  auto* handler = static_cast<PeerEventHandler*>(user_data);
+  if (!handler || !message) return -1;
+  auto callback = handler->EnterCallback();
+  if (!callback) return -1;
+  if (stage == SignalExchangeStage::IncomingMessage &&
+      !handler->device_login_.Pending()) return 0;
+  try {
+    return handler->device_login_.Exchange(stage,
+        nlohmann::json::parse(message, message + size),
+        handler->owner_.trusted_devices_.get(), response, capacity);
+  } catch (const std::exception&) {
+    LOG_ERROR("Device login protocol or identity unavailable");
+    return -1;
+  }
+}
+
 void PeerEventHandler::OnSignalMessage(const char* message, size_t size,
                                        void* user_data) {
   auto* handler = static_cast<PeerEventHandler*>(user_data);
@@ -184,13 +202,16 @@ void PeerEventHandler::OnSignalMessage(const char* message, size_t size,
         j.contains("reason") && j["reason"].is_string()
             ? j["reason"].get<std::string>()
             : "Password change failed";
-    runtime->password_change_result_uncertain_ = false;
+    // A rejected replay cannot tell us whether the original request committed.
+    runtime->password_change_result_uncertain_ = runtime->password_change_recovery_ &&
+                                                !runtime->password_change_succeeded_;
     runtime->password_change_result_ready_ = true;
   }
 }
 
 void PeerEventHandler::OnSignalStatus(SignalStatus status, const char* user_id,
                                       size_t user_id_size, void* user_data) {
+  using RecoveryAction = GuiRuntime::CredentialRecoveryAction;
   auto* handler = static_cast<PeerEventHandler*>(user_data);
   if (!handler) return;
   auto callback = handler->EnterCallback();
@@ -212,10 +233,12 @@ void PeerEventHandler::OnSignalStatus(SignalStatus status, const char* user_id,
       SendClientInfo(runtime->peer_, client_id);
       std::lock_guard<std::mutex> lock(runtime->password_change_mutex_);
       if (runtime->credential_recovery_in_progress_) {
-        if (runtime->credential_recovery_attempt_pending_) {
-          runtime->credential_recovery_promote_pending_ = true;
+        if (!handler->device_login_.UsedPassword()) {
+          runtime->credential_recovery_action_ = RecoveryAction::ResumePending;
+        } else if (runtime->credential_recovery_attempt_pending_) {
+          runtime->credential_recovery_action_ = RecoveryAction::PromotePending;
         } else {
-          runtime->credential_recovery_clear_pending_ = true;
+          runtime->credential_recovery_action_ = RecoveryAction::ClearPending;
         }
       }
     } else if (SignalStatus::SignalFailed == status) {
@@ -223,7 +246,7 @@ void PeerEventHandler::OnSignalStatus(SignalStatus status, const char* user_id,
       std::lock_guard<std::mutex> lock(runtime->password_change_mutex_);
       if (runtime->credential_recovery_in_progress_ &&
           runtime->credential_recovery_attempt_pending_) {
-        runtime->credential_recovery_retry_active_ = true;
+        runtime->credential_recovery_action_ = RecoveryAction::RetryActive;
       }
     } else if (SignalStatus::SignalClosed == status) {
       runtime->signal_connected_ = false;

apps/desktop/src/gui/runtime/peer_event_handler.h

@@ -15,6 +15,7 @@
 
 #include "minirtc.h"
 #include "runtime/session_lifecycle.h"
+#include "runtime/device_login.h"
 
 namespace crossdesk {
 
@@ -63,6 +64,9 @@ public:
                              size_t user_id_size, void *user_data);
   static void OnSignalMessage(const char *message, size_t size,
                               void *user_data);
+  static int OnSignalExchange(SignalExchangeStage stage, const char* message,
+                              size_t size, char* response, size_t capacity,
+                              void* user_data);
   static void OnConnectionStatus(ConnectionStatus status, const char *user_id,
                                  size_t user_id_size, void *user_data);
   static void OnNetStatusReport(const char *client_id, size_t client_id_size,
@@ -85,6 +89,7 @@ private:
   size_t early_data_bytes_ = 0;
 
   GuiRuntime& owner_;
+  DeviceLogin device_login_;
   gui_detail::SessionCallbackGate callbacks_;
 };
 

apps/desktop/src/gui/runtime/runtime_state.h

@@ -167,21 +167,23 @@ struct UserSettingsState {
 };
 
 struct PasswordChangeState {
+  enum class CredentialRecoveryAction {
+    None, RetryActive, PromotePending, ClearPending, ResumePending
+  };
   std::mutex password_change_mutex_;
   uint64_t next_password_change_request_id_ = 0;
   bool password_change_pending_ = false;
   bool password_change_result_ready_ = false;
   bool password_change_succeeded_ = false;
   bool password_change_result_uncertain_ = false;
+  bool password_change_recovery_ = false;
   std::chrono::steady_clock::time_point password_change_requested_at_;
   std::string pending_password_change_request_id_;
   std::string pending_local_password_;
   std::string password_change_error_;
   bool credential_recovery_in_progress_ = false;
   bool credential_recovery_attempt_pending_ = false;
-  bool credential_recovery_retry_active_ = false;
-  bool credential_recovery_promote_pending_ = false;
-  bool credential_recovery_clear_pending_ = false;
+  CredentialRecoveryAction credential_recovery_action_ = CredentialRecoveryAction::None;
 };
 
 struct ConnectionState {

apps/desktop/src/gui/runtime/trusted_devices.cpp

@@ -156,15 +156,19 @@ nlohmann::json TrustedDevices::Prove(const std::string& nonce,
   Require(IsHex(nonce, 32) && Label(device_id) && Label(name));
   const Device device{public_key_, name, device_id};
   const auto text = Transcript(nonce, device);
+  return {{"type", "device_trust_proof"}, {"version", 1}, {"nonce", nonce},
+          {"public_key", public_key_}, {"device_id", device_id}, {"name", name},
+          {"signature", Sign(text)}};
+}
+
+std::string TrustedDevices::Sign(std::string_view text) const {
   Context context(EVP_MD_CTX_new(), EVP_MD_CTX_free);
   std::array<uint8_t, 64> signature{};
   size_t size = signature.size();
   Require(context && EVP_DigestSignInit(context.get(), nullptr, nullptr, nullptr, key_.get()) == 1 &&
           EVP_DigestSign(context.get(), signature.data(), &size,
                          reinterpret_cast<const uint8_t*>(text.data()), text.size()) == 1 && size == 64);
-  return {{"type", "device_trust_proof"}, {"version", 1}, {"nonce", nonce},
-          {"public_key", public_key_}, {"device_id", device_id}, {"name", name},
-          {"signature", Hex(signature.data(), signature.size())}};
+  return Hex(signature.data(), signature.size());
 }
 
 std::optional<TrustedDevices::Device> TrustedDevices::Verify(

apps/desktop/src/gui/runtime/trusted_devices.h

@@ -31,6 +31,9 @@ class TrustedDevices {
   TrustedDevices(const std::filesystem::path& directory,
                  const std::filesystem::path& cache);
   std::string Fingerprint() const;
+  const std::string& PublicKey() const { return public_key_; }
+  // Callers supply a canonical, purpose-specific transcript.
+  std::string Sign(std::string_view transcript) const;
   static std::string Fingerprint(const std::string& public_key);
   static std::string Nonce();
   nlohmann::json Prove(const std::string& nonce,