fix(vnc): support RA2_256 Raspberry Pi connections

README.md

@@ -100,7 +100,7 @@ NyaTerm is built for people who move between servers, local commands, devices, a
 
 - SSH, Local Terminal, Telnet, Serial, RDP, and VNC session support
 - Multi-tab workspace with horizontal and vertical pane splits, tab drag docking, and layout restoration
-- RDP and VNC remote desktop panes; VNC currently supports direct TCP, None / classic VNC Auth, Raw / ZRLE / Tight / Tight JPEG framebuffer updates, window scaling, bounded reconnects, and text clipboard exchange for Latin-1 text
+- RDP and VNC remote desktop panes; VNC supports direct TCP, None / classic VNC Auth, RA2_256 in Auto mode with server-key TOFU verification, Raw / ZRLE / Tight / Tight JPEG framebuffer updates, window scaling, bounded reconnects, and text clipboard exchange for Latin-1 text
 - Saved connections with folders, icons, metadata, duplication, keyboard copy, reconnect, and import flows
 - Command Palette and session quick switcher for finding actions, open sessions, saved connections, and new-session entry points
 - Main-window `Background Image` customization with `cover` / `contain` / `stretch` / `tile` sizing and adjustable `Background Content Opacity`

src-tauri/Cargo.lock

@@ -950,6 +950,17 @@ dependencies = [
  "error-code",
 ]
 
+[[package]]
+name = "cmac"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8543454e3c3f5126effff9cd44d562af4e31fb8ce1cc0d3dcd8f084515dbc1aa"
+dependencies = [
+ "cipher 0.4.4",
+ "dbl",
+ "digest 0.10.7",
+]
+
 [[package]]
 name = "cmake"
 version = "0.1.58"
@@ -1500,6 +1511,15 @@ version = "2.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4583a4551df46e2792f82ceeac45e850d2e2d5debba0b91f102385cda5b11f06"
 
+[[package]]
+name = "dbl"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd2735a791158376708f9347fe8faba9667589d82427ef3aed6794a8981de3d9"
+dependencies = [
+ "generic-array 0.14.7",
+]
+
 [[package]]
 name = "dbus"
 version = "0.9.12"
@@ -1586,6 +1606,7 @@ dependencies = [
  "const-oid 0.9.6",
  "der_derive 0.7.3",
  "flagset",
+ "pem-rfc7468 0.7.0",
  "zeroize",
 ]
 
@@ -1900,6 +1921,19 @@ version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d0881ea181b1df73ff77ffaaf9c7544ecc11e82fba9b5f27b262a3c73a332555"
 
+[[package]]
+name = "eax"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9954fabd903b82b9d7a68f65f97dc96dd9ad368e40ccc907a7c19d53e6bfac28"
+dependencies = [
+ "aead 0.5.2",
+ "cipher 0.4.4",
+ "cmac",
+ "ctr 0.9.2",
+ "subtle",
+]
+
 [[package]]
 name = "ecdsa"
 version = "0.16.9"
@@ -9507,10 +9541,15 @@ checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
 name = "vnc-rs"
 version = "0.5.3"
 dependencies = [
+ "aes 0.8.4",
  "async_io_stream",
+ "eax",
  "flate2",
  "futures",
  "image",
+ "rand 0.8.8",
+ "rsa 0.9.10",
+ "sha2 0.10.9",
  "thiserror 1.0.69",
  "tokio",
  "tokio-stream",

src-tauri/src/cmd/connection.rs

@@ -899,6 +899,7 @@ e+JpiSq66Z6GIt0801skPh20jxOO3F52SoX1IeO5D5PXfZrfSZlw6S8c7bwyp2FHxDewRx
             config: ConnectionType::Vnc {
                 host: "example.com".to_string(),
                 port: 5900,
+                username: String::new(),
                 security: VncSecuritySettings::default(),
                 display: VncDisplaySettings::default(),
                 clipboard: VncClipboardSettings::default(),

src-tauri/src/cmd/vnc.rs

@@ -60,6 +60,15 @@ pub async fn vnc_reconnect(
     state.inner().clone().reconnect(app, &session_id).await
 }
 
+#[tauri::command]
+pub async fn respond_vnc_server_key(
+    state: tauri::State<'_, Arc<VncSessionManager>>,
+    request_id: String,
+    accepted: bool,
+) -> AppResult<()> {
+    state.respond_server_key(&request_id, accepted).await
+}
+
 #[tauri::command]
 pub async fn close_vnc_session(
     app: tauri::AppHandle,

src-tauri/src/config/connection.rs

@@ -724,6 +724,8 @@ pub enum ConnectionType {
         #[serde(default = "default_vnc_port")]
         port: u16,
         #[serde(default)]
+        username: String,
+        #[serde(default)]
         security: VncSecuritySettings,
         #[serde(default)]
         display: VncDisplaySettings,
@@ -2721,6 +2723,7 @@ mod tests {
 
         let ConnectionType::Vnc {
             port,
+            username,
             security,
             display,
             clipboard,
@@ -2734,6 +2737,7 @@ mod tests {
         };
 
         assert_eq!(port, 5900);
+        assert!(username.is_empty());
         assert_eq!(security.mode, "auto");
         assert_eq!(display.scale_mode, "fit");
         assert!(clipboard.enabled);

src-tauri/src/core/vnc.rs

@@ -2,17 +2,18 @@ use crate::config::{self, ConnectionAuth, ConnectionNetwork, ConnectionType};
 use crate::core::network::open_tcp_transport;
 use crate::error::{AppError, AppResult};
 use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
 use std::collections::{HashMap, VecDeque};
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
 use tauri::async_runtime::JoinHandle;
 use tauri::ipc::{Channel, InvokeResponseBody};
 use tauri::{AppHandle, Emitter};
-use tokio::sync::{Mutex, mpsc, watch};
+use tokio::sync::{Mutex, mpsc, oneshot, watch};
 use tokio::time::{Duration, timeout};
 use vnc::{
     ClientKeyEvent, ClientMouseEvent, PixelFormat, Rect, Screen, VncClient, VncConnector,
-    VncEncoding, VncError, VncEvent, VncLimits, VncSecurityPolicy, X11Event,
+    VncEncoding, VncError, VncEvent, VncLimits, VncSecurityPolicy, VncServerKey, X11Event,
 };
 use zeroize::Zeroizing;
 
@@ -28,6 +29,8 @@ const WORKER_COMMAND_CHANNEL_CAPACITY: usize = 256;
 const MAX_PENDING_FRAMES: usize = 2;
 const CONNECT_TIMEOUT: Duration = Duration::from_secs(15);
 const HANDSHAKE_TIMEOUT: Duration = Duration::from_secs(30);
+const RA2_HANDSHAKE_TIMEOUT: Duration = Duration::from_secs(75);
+const SERVER_KEY_PROMPT_TIMEOUT: Duration = Duration::from_secs(60);
 const WORKER_SHUTDOWN_TIMEOUT: Duration = Duration::from_secs(3);
 const EVENT_POLL_INTERVAL: Duration = Duration::from_millis(8);
 const UPDATE_REQUEST_INTERVAL: Duration = Duration::from_millis(16);
@@ -64,6 +67,18 @@ pub struct VncStateEvent {
     pub error_kind: Option<VncErrorKind>,
 }
 
+#[derive(Debug, Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct VncServerKeyVerifyEvent {
+    pub request_id: String,
+    pub session_id: String,
+    pub host: String,
+    pub port: u16,
+    pub fingerprint: String,
+    pub key_bits: u32,
+    pub known_host_status: String,
+}
+
 #[derive(Debug, Clone, Serialize)]
 #[serde(rename_all = "camelCase")]
 pub struct VncClipboardEvent {
@@ -94,6 +109,12 @@ enum VncWorkerCommand {
     FullRefresh,
 }
 
+struct VncServerKeyPending {
+    session_id: String,
+    generation: u64,
+    responder: oneshot::Sender<bool>,
+}
+
 #[derive(Debug, Clone)]
 pub struct VncConnectConfig {
     pub session_id: String,
@@ -101,6 +122,7 @@ pub struct VncConnectConfig {
     pub name: String,
     pub host: String,
     pub port: u16,
+    pub username: String,
     pub password: Option<String>,
     pub security_mode: String,
     pub scale_mode: String,
@@ -200,16 +222,19 @@ pub struct VncSession {
     cancel_sender: Mutex<Option<watch::Sender<bool>>>,
     worker: Mutex<Option<JoinHandle<()>>>,
     close_requested: AtomicBool,
+    pending_server_keys: Arc<Mutex<HashMap<String, VncServerKeyPending>>>,
 }
 
 pub struct VncSessionManager {
     sessions: Mutex<HashMap<String, Arc<VncSession>>>,
+    pending_server_keys: Arc<Mutex<HashMap<String, VncServerKeyPending>>>,
 }
 
 impl VncSessionManager {
     pub fn new() -> Self {
         Self {
             sessions: Mutex::new(HashMap::new()),
+            pending_server_keys: Arc::new(Mutex::new(HashMap::new())),
         }
     }
 
@@ -234,6 +259,7 @@ impl VncSessionManager {
             cancel_sender: Mutex::new(None),
             worker: Mutex::new(None),
             close_requested: AtomicBool::new(false),
+            pending_server_keys: self.pending_server_keys.clone(),
         });
         self.sessions
             .lock()
@@ -312,6 +338,8 @@ impl VncSessionManager {
 
     pub async fn reconnect(self: &Arc<Self>, app: AppHandle, session_id: &str) -> AppResult<()> {
         let session = self.get(session_id).await?;
+        self.cancel_pending_server_keys_for_session(session_id)
+            .await;
         stop_worker(&session).await;
         session.close_requested.store(false, Ordering::Release);
         *session.framebuffer.lock().await = None;
@@ -327,6 +355,8 @@ impl VncSessionManager {
             return Ok(());
         };
         session.close_requested.store(true, Ordering::Release);
+        self.cancel_pending_server_keys_for_session(session_id)
+            .await;
         stop_worker(&session).await;
         session.frame_attach_id.fetch_add(1, Ordering::AcqRel);
         *session.frame_channel.lock().await = None;
@@ -338,6 +368,36 @@ impl VncSessionManager {
         Ok(())
     }
 
+    pub async fn respond_server_key(&self, request_id: &str, accepted: bool) -> AppResult<()> {
+        let Some(pending) = self.pending_server_keys.lock().await.remove(request_id) else {
+            return Err(AppError::Cancelled(format!(
+                "No pending VNC server key request with id '{request_id}'"
+            )));
+        };
+        if let Ok(session) = self.get(&pending.session_id).await
+            && session.generation.load(Ordering::Acquire) != pending.generation
+        {
+            return Ok(());
+        }
+        let _ = pending.responder.send(accepted);
+        Ok(())
+    }
+
+    async fn cancel_pending_server_keys_for_session(&self, session_id: &str) {
+        let mut pending = self.pending_server_keys.lock().await;
+        let request_ids = pending
+            .iter()
+            .filter_map(|(request_id, request)| {
+                (request.session_id == session_id).then(|| request_id.clone())
+            })
+            .collect::<Vec<_>>();
+        for request_id in request_ids {
+            if let Some(request) = pending.remove(&request_id) {
+                let _ = request.responder.send(false);
+            }
+        }
+    }
+
     pub async fn close_all(&self, app: &AppHandle) {
         let ids = self
             .sessions
@@ -470,7 +530,7 @@ async fn run_protocol_generation(
     set_state(session, VncSessionState::Authenticating, None, None).await;
     emit_state(app, session, VncSessionState::Authenticating, None, None);
     let password = Zeroizing::new(session.config.password.clone().unwrap_or_default());
-    if password.as_bytes().len() > 8 {
+    if session.config.security_mode == "vnc-auth" && password.len() > 8 {
         return Err((
             VncErrorKind::Authentication,
             "Classic VNC authentication passwords must be 8 bytes or fewer".to_string(),
@@ -493,12 +553,24 @@ async fn run_protocol_generation(
         ..VncLimits::default()
     };
     let auth_password = password.to_string();
+    let has_credentials = session.config.password.is_some();
+    let handshake_timeout = if session.config.security_mode == "auto" && has_credentials {
+        RA2_HANDSHAKE_TIMEOUT
+    } else {
+        HANDSHAKE_TIMEOUT
+    };
+    let verifier_app = app.clone();
+    let verifier_session = session.clone();
     let state = VncConnector::new(stream)
         .set_auth_method(async move { Ok(auth_password) })
-        .set_security_policy(security_policy(
-            &session.config.security_mode,
-            session.config.password.is_some(),
-        ))
+        .set_credentials_available(has_credentials)
+        .set_username(session.config.username.clone())
+        .set_server_key_verifier(move |server_key| {
+            let app = verifier_app.clone();
+            let session = verifier_session.clone();
+            async move { verify_vnc_server_key(&app, &session, generation, &server_key).await }
+        })
+        .set_security_policy(security_policy(&session.config.security_mode))
         .set_pixel_format(PixelFormat::rgba())
         .set_limits(limits)
         .add_encoding(VncEncoding::DesktopSizePseudo)
@@ -508,7 +580,7 @@ async fn run_protocol_generation(
         .allow_shared(session.config.shared)
         .build()
         .map_err(classify_vnc_error)?;
-    let client = timeout(HANDSHAKE_TIMEOUT, state.try_start())
+    let client = timeout(handshake_timeout, state.try_start())
         .await
         .map_err(|_| {
             (
@@ -575,15 +647,90 @@ fn vnc_connect_target(config: &VncConnectConfig) -> (&str, u16) {
     (config.host.as_str(), config.port)
 }
 
-fn security_policy(mode: &str, has_password: bool) -> VncSecurityPolicy {
+fn security_policy(mode: &str) -> VncSecurityPolicy {
     match mode {
         "none" => VncSecurityPolicy::NoneOnly,
         "vnc-auth" => VncSecurityPolicy::VncAuthOnly,
-        _ if has_password => VncSecurityPolicy::VncAuthOnly,
-        _ => VncSecurityPolicy::NoneOnly,
+        _ => VncSecurityPolicy::Auto,
     }
 }
 
+async fn verify_vnc_server_key(
+    app: &AppHandle,
+    session: &Arc<VncSession>,
+    generation: u64,
+    server_key: &VncServerKey,
+) -> Result<(), VncError> {
+    if session.generation.load(Ordering::Acquire) != generation {
+        return Err(VncError::Ra2ServerKeyRejected(
+            "stale VNC connection generation".to_string(),
+        ));
+    }
+
+    let fingerprint = format!(
+        "SHA256:{}",
+        hex::encode(Sha256::digest(server_key.encoded()))
+    );
+    let known_host_status = crate::storage::check_vnc_known_host(
+        &session.config.host,
+        session.config.port,
+        &fingerprint,
+    )
+    .map_err(|error| VncError::Ra2ServerKeyRejected(error.to_string()))?;
+    if known_host_status == crate::storage::KnownHostCheck::Match {
+        return Ok(());
+    }
+
+    let request_id = uuid::Uuid::new_v4().to_string();
+    let (tx, rx) = oneshot::channel();
+    session.pending_server_keys.lock().await.insert(
+        request_id.clone(),
+        VncServerKeyPending {
+            session_id: session.config.session_id.clone(),
+            generation,
+            responder: tx,
+        },
+    );
+    let payload = VncServerKeyVerifyEvent {
+        request_id: request_id.clone(),
+        session_id: session.config.session_id.clone(),
+        host: session.config.host.clone(),
+        port: session.config.port,
+        fingerprint: fingerprint.clone(),
+        key_bits: server_key.bits(),
+        known_host_status: match known_host_status {
+            crate::storage::KnownHostCheck::Match => "match",
+            crate::storage::KnownHostCheck::HostSeen => "changed",
+            crate::storage::KnownHostCheck::UnknownHost => "unknown",
+        }
+        .to_string(),
+    };
+    let _ = app.emit("vnc-server-key-verify", payload);
+
+    let accepted = match timeout(SERVER_KEY_PROMPT_TIMEOUT, rx).await {
+        Ok(Ok(accepted)) => accepted,
+        _ => {
+            session.pending_server_keys.lock().await.remove(&request_id);
+            return Err(VncError::Ra2ServerKeyRejected(
+                "verification timed out".to_string(),
+            ));
+        }
+    };
+    if session.generation.load(Ordering::Acquire) != generation {
+        return Err(VncError::Ra2ServerKeyRejected(
+            "stale VNC connection generation".to_string(),
+        ));
+    }
+    if !accepted {
+        return Err(VncError::Ra2ServerKeyRejected(
+            "user rejected the server key".to_string(),
+        ));
+    }
+    crate::storage::upsert_vnc_known_host(&session.config.host, session.config.port, &fingerprint)
+        .map_err(|error| VncError::Ra2ServerKeyRejected(error.to_string()))?;
+    Ok(())
+}
+
 async fn handle_vnc_event(
     app: &AppHandle,
     session: &Arc<VncSession>,
@@ -910,18 +1057,24 @@ fn classify_vnc_error(error: VncError) -> (VncErrorKind, String, bool) {
             "VNC authentication failed".to_string(),
             false,
         ),
+        VncError::CredentialTooLong { .. } | VncError::Ra2ServerKeyRejected(_) => {
+            (VncErrorKind::Authentication, error.to_string(), false)
+        }
         VncError::UnsupportedSecurityType
         | VncError::RequiredSecurityTypeUnavailable(_)
         | VncError::InvalidSecurityType(_) => (
             VncErrorKind::Authentication,
             format!(
-                "The VNC server requires an unsupported security type. Currently supported: None and VNC Authentication. Details: {error}"
+                "The VNC server requires an unsupported security type. Currently supported: None, VNC Authentication, and RA2_256 in Auto mode. Details: {error}"
             ),
             false,
         ),
         VncError::InvalidEncoding(_) | VncError::InvalidImageData => {
             (VncErrorKind::Encoding, error.to_string(), false)
         }
+        VncError::IoError(ref source) if source.kind() == std::io::ErrorKind::InvalidData => {
+            (VncErrorKind::Protocol, error.to_string(), false)
+        }
         VncError::IoError(_) => (VncErrorKind::Transport, error.to_string(), true),
         VncError::LimitExceeded { .. }
         | VncError::InvalidDimensions
@@ -929,7 +1082,16 @@ fn classify_vnc_error(error: VncError) -> (VncErrorKind, String, bool) {
         | VncError::WrongPixelFormat
         | VncError::WrongServerMessage
         | VncError::InvalidSecurityResult(_)
-        | VncError::SecurityFailure(_) => (VncErrorKind::Protocol, error.to_string(), false),
+        | VncError::SecurityFailure(_)
+        | VncError::InvalidRa2KeyLength { .. }
+        | VncError::InvalidRa2PublicKey
+        | VncError::InvalidRa2EncryptedRandomLength { .. }
+        | VncError::InvalidRa2RandomLength(_)
+        | VncError::Ra2ServerHashMismatch
+        | VncError::InvalidRa2Subtype(_)
+        | VncError::Ra2ServerKeyVerifierRequired
+        | VncError::InvalidRa2RecordLimit(_)
+        | VncError::Ra2Crypto(_) => (VncErrorKind::Protocol, error.to_string(), false),
         _ => (VncErrorKind::Internal, error.to_string(), true),
     }
 }
@@ -979,6 +1141,7 @@ pub fn load_saved_vnc_config(app: &AppHandle, connection_id: &str) -> AppResult<
     let ConnectionType::Vnc {
         host,
         port,
+        username,
         security,
         display,
         clipboard,
@@ -996,8 +1159,9 @@ pub fn load_saved_vnc_config(app: &AppHandle, connection_id: &str) -> AppResult<
             "VNC Authentication requires a password".to_string(),
         ));
     }
-    if let Some(password) = password.as_ref()
-        && password.as_bytes().len() > 8
+    if security.mode == "vnc-auth"
+        && let Some(password) = password.as_ref()
+        && password.len() > 8
     {
         return Err(AppError::Config(
             "Classic VNC authentication passwords must be 8 bytes or fewer".to_string(),
@@ -1010,6 +1174,7 @@ pub fn load_saved_vnc_config(app: &AppHandle, connection_id: &str) -> AppResult<
         name: connection.name,
         host,
         port,
+        username,
         password,
         security_mode: security.mode,
         scale_mode: display.scale_mode,
@@ -1090,16 +1255,9 @@ mod tests {
 
     #[test]
     fn security_mode_maps_to_fail_closed_policy() {
-        assert_eq!(security_policy("none", true), VncSecurityPolicy::NoneOnly);
-        assert_eq!(
-            security_policy("vnc-auth", false),
-            VncSecurityPolicy::VncAuthOnly
-        );
-        assert_eq!(
-            security_policy("auto", true),
-            VncSecurityPolicy::VncAuthOnly
-        );
-        assert_eq!(security_policy("auto", false), VncSecurityPolicy::NoneOnly);
+        assert_eq!(security_policy("none"), VncSecurityPolicy::NoneOnly);
+        assert_eq!(security_policy("vnc-auth"), VncSecurityPolicy::VncAuthOnly);
+        assert_eq!(security_policy("auto"), VncSecurityPolicy::Auto);
     }
 
     #[test]
@@ -1110,6 +1268,7 @@ mod tests {
             name: "IPv6 VNC".to_string(),
             host: "::1".to_string(),
             port: 5900,
+            username: String::new(),
             password: None,
             security_mode: "none".to_string(),
             scale_mode: "fit".to_string(),
@@ -1133,6 +1292,7 @@ mod tests {
                 name: "Test VNC".to_string(),
                 host: "127.0.0.1".to_string(),
                 port: 5900,
+                username: String::new(),
                 password: None,
                 security_mode: "none".to_string(),
                 scale_mode: "fit".to_string(),
@@ -1156,6 +1316,7 @@ mod tests {
             cancel_sender: Mutex::new(None),
             worker: Mutex::new(None),
             close_requested: AtomicBool::new(false),
+            pending_server_keys: Arc::new(Mutex::new(HashMap::new())),
         });
 
         queue_or_send_frame(&session, vec![1]).await;

src-tauri/src/lib.rs

@@ -236,6 +236,7 @@ pub fn run() {
             cmd::vnc::vnc_input_batch,
             cmd::vnc::vnc_set_clipboard_text,
             cmd::vnc::vnc_reconnect,
+            cmd::vnc::respond_vnc_server_key,
             cmd::vnc::close_vnc_session,
             cmd::session::cancel_session_creation,
             cmd::session::list_serial_ports,

src-tauri/src/storage/migration.rs

@@ -166,6 +166,8 @@ impl Storage {
         txn.open_table(KNOWN_HOSTS_TABLE).map_err(storage_error)?;
         txn.open_table(RDP_KNOWN_HOSTS_TABLE)
             .map_err(storage_error)?;
+        txn.open_table(VNC_KNOWN_HOSTS_TABLE)
+            .map_err(storage_error)?;
         txn.open_table(NOTE_FOLDERS_TABLE).map_err(storage_error)?;
         txn.open_table(NOTES_TABLE).map_err(storage_error)?;
         txn.open_table(NOTE_SUMMARIES_TABLE)
@@ -193,6 +195,8 @@ pub(super) fn open_all_v3_tables(txn: &redb::WriteTransaction) -> AppResult<()>
     txn.open_table(KNOWN_HOSTS_TABLE).map_err(storage_error)?;
     txn.open_table(RDP_KNOWN_HOSTS_TABLE)
         .map_err(storage_error)?;
+    txn.open_table(VNC_KNOWN_HOSTS_TABLE)
+        .map_err(storage_error)?;
     txn.open_table(COMMAND_HISTORY_TABLE)
         .map_err(storage_error)?;
     txn.open_table(NOTE_FOLDERS_TABLE).map_err(storage_error)?;

src-tauri/src/storage/mod.rs

@@ -13,6 +13,7 @@ mod sessions;
 mod settings_impl;
 mod tables;
 mod util;
+mod vnc_known_hosts;
 
 #[cfg(test)]
 mod tests;
@@ -26,7 +27,7 @@ pub use tables::{
     IDX_CONNECTIONS_BY_GROUP_TABLE, IDX_CONNECTIONS_BY_LAST_USED_TABLE,
     IDX_CONNECTIONS_BY_PROTOCOL_TABLE, KNOWN_HOSTS_TABLE, META_TABLE, NOTE_FOLDERS_TABLE,
     NOTES_TABLE, OTP_ACCOUNTS_TABLE, PROXIES_TABLE, RDP_KNOWN_HOSTS_TABLE, SETTINGS_TABLE,
-    TUNNELS_TABLE,
+    TUNNELS_TABLE, VNC_KNOWN_HOSTS_TABLE,
 };
 
 use crate::error::{AppError, AppResult};
@@ -341,6 +342,22 @@ pub(crate) fn upsert_rdp_known_host(
     storage()?.upsert_rdp_known_host(host, port, sha256_fingerprint, certificate)
 }
 
+pub(crate) fn check_vnc_known_host(
+    host: &str,
+    port: u16,
+    sha256_fingerprint: &str,
+) -> AppResult<KnownHostCheck> {
+    storage()?.check_vnc_known_host(host, port, sha256_fingerprint)
+}
+
+pub(crate) fn upsert_vnc_known_host(
+    host: &str,
+    port: u16,
+    sha256_fingerprint: &str,
+) -> AppResult<()> {
+    storage()?.upsert_vnc_known_host(host, port, sha256_fingerprint)
+}
+
 pub(crate) fn load_master_key_token() -> AppResult<Option<String>> {
     storage()?.load_master_key_token()
 }

src-tauri/src/storage/tables.rs

@@ -26,6 +26,7 @@ pub(super) const TUNNEL_PREFIX: &str = "tunnels/";
 pub(super) const KNOWN_HOST_PREFIX: &str = "known_hosts/";
 pub(super) const KNOWN_HOST_RAW_PREFIX: &str = "known_hosts/raw/";
 pub(super) const RDP_KNOWN_HOST_PREFIX: &str = "rdp_known_hosts/";
+pub(super) const VNC_KNOWN_HOST_PREFIX: &str = "vnc_known_hosts/";
 pub(super) const COMMAND_HISTORY_PREFIX: &str = "command_history/";
 pub(super) const NOTE_FOLDER_PREFIX: &str = "note_folders/";
 pub(super) const NOTE_DOCUMENT_PREFIX: &str = "notes/";
@@ -45,6 +46,8 @@ pub const TUNNELS_TABLE: TableDefinition<&str, &[u8]> = TableDefinition::new("tu
 pub const KNOWN_HOSTS_TABLE: TableDefinition<&str, &[u8]> = TableDefinition::new("known_hosts");
 pub const RDP_KNOWN_HOSTS_TABLE: TableDefinition<&str, &[u8]> =
     TableDefinition::new("rdp_known_hosts");
+pub const VNC_KNOWN_HOSTS_TABLE: TableDefinition<&str, &[u8]> =
+    TableDefinition::new("vnc_known_hosts");
 pub const COMMAND_HISTORY_TABLE: TableDefinition<&str, &[u8]> =
     TableDefinition::new("command_history");
 pub const NOTE_FOLDERS_TABLE: TableDefinition<&str, &[u8]> = TableDefinition::new("note_folders");
@@ -127,6 +130,15 @@ pub(super) struct RdpKnownHostRecord {
     pub(super) updated_at_ms: u64,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub(super) struct VncKnownHostRecord {
+    pub(super) host: String,
+    pub(super) port: u16,
+    pub(super) sha256_fingerprint: String,
+    pub(super) created_at_ms: u64,
+    pub(super) updated_at_ms: u64,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub(super) struct HistoryStoreFileV2 {
     pub(super) version: u32,

src-tauri/src/storage/tests.rs

@@ -492,3 +492,30 @@ fn known_hosts_management_clear_removes_ssh_records_without_touching_rdp() {
     );
     let _ = fs::remove_dir_all(dir);
 }
+
+#[test]
+fn vnc_known_hosts_distinguish_unknown_match_and_changed_keys() {
+    let (dir, storage) = test_storage("vnc-known-hosts");
+    assert_eq!(
+        storage
+            .check_vnc_known_host("pi.local", 5900, "SHA256:first")
+            .expect("check unknown"),
+        KnownHostCheck::UnknownHost
+    );
+    storage
+        .upsert_vnc_known_host("pi.local", 5900, "SHA256:first")
+        .expect("save fingerprint");
+    assert_eq!(
+        storage
+            .check_vnc_known_host("PI.LOCAL", 5900, "sha256:FIRST")
+            .expect("check match"),
+        KnownHostCheck::Match
+    );
+    assert_eq!(
+        storage
+            .check_vnc_known_host("pi.local", 5900, "SHA256:changed")
+            .expect("check changed"),
+        KnownHostCheck::HostSeen
+    );
+    let _ = fs::remove_dir_all(dir);
+}

src-tauri/src/storage/vnc_known_hosts.rs

@@ -0,0 +1,56 @@
+use crate::error::AppResult;
+
+use super::history::history_id;
+use super::tables::*;
+use super::util::*;
+use super::{KnownHostCheck, Storage};
+
+impl Storage {
+    pub fn check_vnc_known_host(
+        &self,
+        host: &str,
+        port: u16,
+        sha256_fingerprint: &str,
+    ) -> AppResult<KnownHostCheck> {
+        let Some(record) = self.read_json::<VncKnownHostRecord>(
+            VNC_KNOWN_HOSTS_TABLE,
+            &vnc_known_host_key(host, port),
+        )?
+        else {
+            return Ok(KnownHostCheck::UnknownHost);
+        };
+
+        if record
+            .sha256_fingerprint
+            .eq_ignore_ascii_case(sha256_fingerprint)
+        {
+            Ok(KnownHostCheck::Match)
+        } else {
+            Ok(KnownHostCheck::HostSeen)
+        }
+    }
+
+    pub fn upsert_vnc_known_host(
+        &self,
+        host: &str,
+        port: u16,
+        sha256_fingerprint: &str,
+    ) -> AppResult<()> {
+        let now = current_time_ms();
+        let key = vnc_known_host_key(host, port);
+        let existing: Option<VncKnownHostRecord> = self.read_json(VNC_KNOWN_HOSTS_TABLE, &key)?;
+        let record = VncKnownHostRecord {
+            host: host.to_string(),
+            port,
+            sha256_fingerprint: sha256_fingerprint.to_string(),
+            created_at_ms: existing.map_or(now, |record| record.created_at_ms),
+            updated_at_ms: now,
+        };
+        self.write_json(VNC_KNOWN_HOSTS_TABLE, &key, &record)
+    }
+}
+
+pub(super) fn vnc_known_host_key(host: &str, port: u16) -> String {
+    let host_identifier = format!("{}:{}", host.trim().to_ascii_lowercase(), port);
+    format!("{VNC_KNOWN_HOST_PREFIX}{}", history_id(&host_identifier))
+}

src-tauri/vendor/README.md

@@ -47,6 +47,7 @@ This directory contains local copies of upstream crates used by NyaTerm's RDP st
   - Adds configurable limits for strings, dimensions, rectangles, encoded/decoded payloads, clipboard data, and channels.
   - Reduces internal channel capacity and adds deterministic protocol/parser regression tests.
   - Adds an explicit security policy so NyaTerm can fail closed for `none`, `vnc-auth`, or password-aware `auto`.
+  - Adds RA2_256 (security type 129) with bounded RSA key exchange, AES-EAX encrypted records, username/password subtypes, and a pre-credential server-key verification callback used by NyaTerm's TOFU flow.
 - Integration status: used by NyaTerm's VNC direct-TCP manager and React pane. Raw is the required fallback; compressed encodings must remain gated by fork tests and interoperability checks before being advertised.
 
 ## Update Method

src-tauri/vendor/vnc-rs/Cargo.toml

@@ -18,6 +18,11 @@ name = "vnc"
 path = "src/lib.rs"
 
 [dependencies]
+aes = "0.8"
+eax = "0.5"
+rand = "0.8"
+rsa = "0.9"
+sha2 = "0.10"
 #error
 thiserror = "^1"
 flate2 = "^1"

src-tauri/vendor/vnc-rs/VENDOR.md

@@ -12,7 +12,10 @@ NyaTerm vendors this crate to harden its network parser before application
 integration. Local changes forbid unsafe Rust, replace network-controlled panic
 and undefined-behavior paths with typed errors, add bounded protocol limits,
 reduce queue sizes, add explicit security-selection policy, and add
-deterministic handshake/parser regression tests.
+deterministic handshake/parser regression tests. The fork also implements
+RA2_256 (security type 129) with RSA key exchange, AES-EAX records, bounded
+credentials, and an application-provided server-key verifier that runs before
+credentials are sent.
 
 This fork is used by NyaTerm's direct-TCP VNC manager and React pane. Raw must
 remain the required fallback. ZRLE/Tight support should only be advertised after

src-tauri/vendor/vnc-rs/src/client/auth.rs

@@ -11,6 +11,7 @@ pub(super) enum SecurityType {
     VncAuth = 2,
     RA2 = 5,
     RA2ne = 6,
+    RA2_256 = 129,
     Tight = 16,
     Ultra = 17,
     Tls = 18,
@@ -30,6 +31,7 @@ impl TryFrom<u8> for SecurityType {
             2 => Ok(Self::VncAuth),
             5 => Ok(Self::RA2),
             6 => Ok(Self::RA2ne),
+            129 => Ok(Self::RA2_256),
             16 => Ok(Self::Tight),
             17 => Ok(Self::Ultra),
             18 => Ok(Self::Tls),
@@ -108,7 +110,17 @@ impl SecurityType {
                 }
                 let mut sec_types = Vec::with_capacity(num as usize);
                 for _ in 0..num {
-                    sec_types.push(reader.read_u8().await?.try_into()?);
+                    let raw = reader.read_u8().await?;
+                    match raw.try_into() {
+                        Ok(security_type) => sec_types.push(security_type),
+                        Err(VncError::InvalidSecurityType(_)) => {
+                            tracing::trace!(
+                                raw,
+                                "Ignoring unsupported advertised VNC security type"
+                            );
+                        }
+                        Err(error) => return Err(error),
+                    }
                 }
                 tracing::trace!("Server supported security type: {:?}", sec_types);
                 Ok(sec_types)
@@ -235,15 +247,24 @@ mod tests {
     }
 
     #[tokio::test]
-    async fn rejects_unknown_security_type_and_result() {
-        let mut security = &[1_u8, 99][..];
-        let error = SecurityType::read(&mut security, &VncVersion::RFB38, &VncLimits::default())
+    async fn ignores_unknown_security_types_in_rfb38_lists_but_rejects_unknown_results() {
+        let mut security = &[3_u8, 99, 129, 2][..];
+        let types = SecurityType::read(&mut security, &VncVersion::RFB38, &VncLimits::default())
             .await
-            .unwrap_err();
-        assert!(matches!(error, VncError::InvalidSecurityType(99)));
+            .unwrap();
+        assert_eq!(types, vec![SecurityType::RA2_256, SecurityType::VncAuth]);
         assert!(matches!(
             AuthResult::try_from(7),
             Err(VncError::InvalidSecurityResult(7))
         ));
     }
+
+    #[tokio::test]
+    async fn rfb33_keeps_unknown_single_security_type_fail_closed() {
+        let mut security = &99_u32.to_be_bytes()[..];
+        let error = SecurityType::read(&mut security, &VncVersion::RFB33, &VncLimits::default())
+            .await
+            .unwrap_err();
+        assert!(matches!(error, VncError::InvalidSecurityType(99)));
+    }
 }

src-tauri/vendor/vnc-rs/src/client/connector.rs

@@ -1,9 +1,11 @@
 use super::{
     auth::{read_security_failure, AuthHelper, AuthResult, SecurityType},
     connection::VncClient,
+    security::ra2::{self, ServerKeyVerifier, VncServerKey},
 };
 use std::future::Future;
 use std::pin::Pin;
+use std::sync::Arc;
 use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite};
 use tracing::{info, trace};
 
@@ -33,7 +35,7 @@ where
 {
     pub fn try_start(
         self,
-    ) -> Pin<Box<dyn Future<Output = Result<Self, VncError>> + Send + Sync + 'static>> {
+    ) -> Pin<Box<dyn Future<Output = Result<Self, VncError>> + Send + 'static>> {
         Box::pin(async move {
             match self {
                 VncState::Handshake(mut connector) => {
@@ -64,43 +66,52 @@ where
                     )
                     .await?;
 
-                    if connector.security_policy == VncSecurityPolicy::NoneOnly
-                        && !security_types.contains(&SecurityType::None)
-                    {
+                    let selected = match connector.security_policy {
+                        VncSecurityPolicy::NoneOnly => {
+                            if !security_types.contains(&SecurityType::None) {
                                 return Err(VncError::RequiredSecurityTypeUnavailable("none"));
                             }
-                    if connector.security_policy == VncSecurityPolicy::VncAuthOnly
-                        && !security_types.contains(&SecurityType::VncAuth)
-                    {
+                            SecurityType::None
+                        }
+                        VncSecurityPolicy::VncAuthOnly => {
+                            if !security_types.contains(&SecurityType::VncAuth) {
                                 return Err(VncError::RequiredSecurityTypeUnavailable("vnc-auth"));
                             }
-
-                    let prefer_none = match connector.security_policy {
-                        VncSecurityPolicy::Auto => connector.auth_methond.is_none(),
-                        VncSecurityPolicy::NoneOnly => true,
-                        VncSecurityPolicy::VncAuthOnly => false,
+                            SecurityType::VncAuth
+                        }
+                        VncSecurityPolicy::Auto if connector.credentials_available => {
+                            if connector.rfb_version != VncVersion::RFB33
+                                && security_types.contains(&SecurityType::RA2_256)
+                            {
+                                SecurityType::RA2_256
+                            } else if security_types.contains(&SecurityType::VncAuth) {
+                                SecurityType::VncAuth
+                            } else {
+                                return Err(VncError::UnsupportedSecurityType);
+                            }
+                        }
+                        VncSecurityPolicy::Auto => {
+                            if security_types.contains(&SecurityType::None) {
+                                SecurityType::None
+                            } else {
+                                return Err(VncError::UnsupportedSecurityType);
+                            }
+                        }
                     };
 
-                    if prefer_none && security_types.contains(&SecurityType::None) {
+                    let client = match selected {
+                        SecurityType::None => {
                             match connector.rfb_version {
                                 VncVersion::RFB33 => {
-                                // If the security-type is 1, for no authentication, the server does not
-                                // send the SecurityResult message but proceeds directly to the
-                                // initialization messages (Section 7.3).
                                     info!("No auth needed in vnc3.3");
                                 }
                                 VncVersion::RFB37 => {
-                                // After the security handshake, if the security-type is 1, for no
-                                // authentication, the server does not send the SecurityResult message
-                                // but proceeds directly to the initialization messages (Section 7.3).
                                     info!("No auth needed in vnc3.7");
-                                SecurityType::write(&SecurityType::None, &mut connector.stream)
-                                    .await?;
+                                    SecurityType::write(&selected, &mut connector.stream).await?;
                                 }
                                 VncVersion::RFB38 => {
                                     info!("No auth needed in vnc3.8");
-                                SecurityType::write(&SecurityType::None, &mut connector.stream)
-                                    .await?;
+                                    SecurityType::write(&selected, &mut connector.stream).await?;
                                     let result: AuthResult =
                                         connector.stream.read_u32().await?.try_into()?;
                                     if result == AuthResult::Failed {
@@ -113,62 +124,6 @@ where
                                     }
                                 }
                             }
-                    } else {
-                        // choose a auth method
-                        if security_types.contains(&SecurityType::VncAuth) {
-                            if connector.rfb_version != VncVersion::RFB33 {
-                                // In the security handshake (Section 7.1.2), rather than a two-way
-                                // negotiation, the server decides the security type and sends a single
-                                // word:
-
-                                //            +--------------+--------------+---------------+
-                                //            | No. of bytes | Type [Value] | Description   |
-                                //            +--------------+--------------+---------------+
-                                //            | 4            | U32          | security-type |
-                                //            +--------------+--------------+---------------+
-
-                                // The security-type may only take the value 0, 1, or 2.  A value of 0
-                                // means that the connection has failed and is followed by a string
-                                // giving the reason, as described in Section 7.1.2.
-                                SecurityType::write(&SecurityType::VncAuth, &mut connector.stream)
-                                    .await?;
-                            }
-                        } else {
-                            return Err(VncError::UnsupportedSecurityType);
-                        }
-
-                        // get password
-                        if connector.auth_methond.is_none() {
-                            return Err(VncError::NoPassword);
-                        }
-
-                        let credential = connector
-                            .auth_methond
-                            .take()
-                            .ok_or(VncError::NoPassword)?
-                            .await?;
-
-                        // auth
-                        let auth = AuthHelper::read(&mut connector.stream, &credential).await?;
-                        auth.write(&mut connector.stream).await?;
-                        let result = auth.finish(&mut connector.stream).await?;
-                        if let AuthResult::Failed = result {
-                            if let VncVersion::RFB37 = connector.rfb_version {
-                                // In VNC Authentication (Section 7.2.2), if the authentication fails,
-                                // the server sends the SecurityResult message, but does not send an
-                                // error message before closing the connection.
-                                return Err(VncError::WrongPassword);
-                            } else {
-                                let reason =
-                                    read_security_failure(&mut connector.stream, &connector.limits)
-                                        .await?;
-                                return Err(VncError::SecurityFailure(reason));
-                            }
-                        }
-                    }
-                    info!("auth done, client connected");
-
-                    Ok(VncState::Connected(
                             VncClient::new(
                                 connector.stream,
                                 connector.allow_shared,
@@ -176,8 +131,80 @@ where
                                 connector.encodings,
                                 connector.limits,
                             )
-                        .await?,
-                    ))
+                            .await?
+                        }
+                        SecurityType::VncAuth => {
+                            let credential = connector
+                                .auth_methond
+                                .take()
+                                .ok_or(VncError::NoPassword)?
+                                .await?;
+                            if credential.len() > 8 {
+                                return Err(VncError::CredentialTooLong {
+                                    field: "classic VNC password",
+                                    actual: credential.len(),
+                                    limit: 8,
+                                });
+                            }
+                            if connector.rfb_version != VncVersion::RFB33 {
+                                SecurityType::write(&selected, &mut connector.stream).await?;
+                            }
+                            let auth = AuthHelper::read(&mut connector.stream, &credential).await?;
+                            auth.write(&mut connector.stream).await?;
+                            let result = auth.finish(&mut connector.stream).await?;
+                            if let AuthResult::Failed = result {
+                                if let VncVersion::RFB37 = connector.rfb_version {
+                                    return Err(VncError::WrongPassword);
+                                }
+                                let reason =
+                                    read_security_failure(&mut connector.stream, &connector.limits)
+                                        .await?;
+                                return Err(VncError::SecurityFailure(reason));
+                            }
+                            VncClient::new(
+                                connector.stream,
+                                connector.allow_shared,
+                                connector.pixel_format,
+                                connector.encodings,
+                                connector.limits,
+                            )
+                            .await?
+                        }
+                        SecurityType::RA2_256 => {
+                            let verifier = connector
+                                .server_key_verifier
+                                .clone()
+                                .ok_or(VncError::Ra2ServerKeyVerifierRequired)?;
+                            let credential = connector
+                                .auth_methond
+                                .take()
+                                .ok_or(VncError::NoPassword)?
+                                .await?;
+                            let username = connector.username.take().unwrap_or_default();
+                            ra2::validate_credentials(&username, &credential)?;
+                            SecurityType::write(&selected, &mut connector.stream).await?;
+                            let stream = ra2::authenticate(
+                                connector.stream,
+                                username,
+                                credential,
+                                verifier,
+                                connector.limits,
+                                connector.rfb_version,
+                            )
+                            .await?;
+                            VncClient::new(
+                                stream,
+                                connector.allow_shared,
+                                connector.pixel_format,
+                                connector.encodings,
+                                connector.limits,
+                            )
+                            .await?
+                        }
+                        _ => return Err(VncError::UnsupportedSecurityType),
+                    };
+                    info!("auth done, client connected");
+                    Ok(VncState::Connected(client))
                 }
                 VncState::Connected(_) => Err(VncError::ConnectError),
             }
@@ -201,6 +228,9 @@ where
 {
     stream: S,
     auth_methond: Option<F>,
+    credentials_available: bool,
+    username: Option<String>,
+    server_key_verifier: Option<ServerKeyVerifier>,
     security_policy: VncSecurityPolicy,
     rfb_version: VncVersion,
     allow_shared: bool,
@@ -245,6 +275,9 @@ where
         Self {
             stream,
             auth_methond: None,
+            credentials_available: false,
+            username: None,
+            server_key_verifier: None,
             security_policy: VncSecurityPolicy::Auto,
             allow_shared: true,
             rfb_version: VncVersion::RFB38,
@@ -295,6 +328,26 @@ where
     ///
     pub fn set_auth_method(mut self, auth_callback: F) -> Self {
         self.auth_methond = Some(auth_callback);
+        self.credentials_available = true;
+        self
+    }
+
+    pub fn set_credentials_available(mut self, available: bool) -> Self {
+        self.credentials_available = available;
+        self
+    }
+
+    pub fn set_username(mut self, username: impl Into<String>) -> Self {
+        self.username = Some(username.into());
+        self
+    }
+
+    pub fn set_server_key_verifier<V, Fut>(mut self, verifier: V) -> Self
+    where
+        V: Fn(VncServerKey) -> Fut + Send + Sync + 'static,
+        Fut: Future<Output = Result<(), VncError>> + Send + 'static,
+    {
+        self.server_key_verifier = Some(Arc::new(move |key| Box::pin(verifier(key))));
         self
     }
 
@@ -406,7 +459,10 @@ mod tests {
             .unwrap()
     }
 
-    async fn write_server_init(server: &mut DuplexStream) {
+    async fn write_server_init<S>(server: &mut S)
+    where
+        S: AsyncRead + AsyncWrite + Unpin,
+    {
         server.write_all(&2_u16.to_be_bytes()).await.unwrap();
         server.write_all(&2_u16.to_be_bytes()).await.unwrap();
         server
@@ -615,6 +671,49 @@ mod tests {
         server_task.await.unwrap();
     }
 
+    async fn run_ra2_handshake(subtype: u8, expected_username: &'static str) {
+        let (client, mut server) = tokio::io::duplex(16 * 1024);
+        let limits = VncLimits::default();
+        let server_task = tokio::spawn(async move {
+            server.write_all(b"RFB 003.008\n").await.unwrap();
+            let mut version = [0_u8; 12];
+            server.read_exact(&mut version).await.unwrap();
+            assert_eq!(&version, b"RFB 003.008\n");
+            server.write_all(&[4, 99, 1, 2, 129]).await.unwrap();
+            assert_eq!(server.read_u8().await.unwrap(), 129);
+
+            let mut encrypted = crate::client::security::ra2::accept_test_handshake(
+                server,
+                subtype,
+                expected_username,
+                "raspberry",
+                limits,
+            )
+            .await;
+            assert_eq!(encrypted.read_u8().await.unwrap(), 1);
+            write_server_init(&mut encrypted).await;
+        });
+
+        let state = VncConnector::new(client)
+            .set_auth_method(async { Ok("raspberry".to_owned()) })
+            .set_credentials_available(true)
+            .set_username("pi")
+            .set_server_key_verifier(|key| async move {
+                assert!(key.bits() >= 2048);
+                assert!(!key.encoded().is_empty());
+                Ok(())
+            })
+            .set_security_policy(VncSecurityPolicy::Auto)
+            .add_encoding(VncEncoding::Raw)
+            .build()
+            .unwrap()
+            .try_start()
+            .await
+            .unwrap();
+        state.finish().unwrap().close().await.unwrap();
+        server_task.await.unwrap();
+    }
+
     #[tokio::test]
     async fn none_security_33_37_38() {
         run_none_handshake(VncVersion::RFB33).await;
@@ -622,6 +721,63 @@ mod tests {
         run_none_handshake(VncVersion::RFB38).await;
     }
 
+    #[tokio::test]
+    async fn ra2_256_auto_prefers_encrypted_auth_and_supports_both_subtypes() {
+        run_ra2_handshake(1, "pi").await;
+        run_ra2_handshake(2, "").await;
+    }
+
+    #[tokio::test]
+    async fn auto_with_credentials_never_downgrades_to_none() {
+        let (client, mut server) = tokio::io::duplex(128);
+        tokio::spawn(async move {
+            server.write_all(b"RFB 003.008\n").await.unwrap();
+            let mut version = [0_u8; 12];
+            server.read_exact(&mut version).await.unwrap();
+            server.write_all(&[1, 1]).await.unwrap();
+        });
+
+        let result = VncConnector::new(client)
+            .set_auth_method(async { Ok("password".to_owned()) })
+            .set_credentials_available(true)
+            .set_security_policy(VncSecurityPolicy::Auto)
+            .add_encoding(VncEncoding::Raw)
+            .build()
+            .unwrap()
+            .try_start()
+            .await;
+        assert!(matches!(result, Err(VncError::UnsupportedSecurityType)));
+    }
+
+    #[tokio::test]
+    async fn classic_vnc_auth_keeps_the_eight_byte_limit() {
+        let (client, mut server) = tokio::io::duplex(128);
+        tokio::spawn(async move {
+            server.write_all(b"RFB 003.008\n").await.unwrap();
+            let mut version = [0_u8; 12];
+            server.read_exact(&mut version).await.unwrap();
+            server.write_all(&[1, 2]).await.unwrap();
+        });
+
+        let result = VncConnector::new(client)
+            .set_auth_method(async { Ok("123456789".to_owned()) })
+            .set_credentials_available(true)
+            .set_security_policy(VncSecurityPolicy::Auto)
+            .add_encoding(VncEncoding::Raw)
+            .build()
+            .unwrap()
+            .try_start()
+            .await;
+        assert!(matches!(
+            result,
+            Err(VncError::CredentialTooLong {
+                field: "classic VNC password",
+                actual: 9,
+                limit: 8
+            })
+        ));
+    }
+
     #[tokio::test]
     async fn scripted_rfb_none_decodes_zrle_tight_and_jpeg_as_raw() {
         let zrle = run_scripted_framebuffer(

src-tauri/vendor/vnc-rs/src/client/mod.rs

@@ -6,3 +6,4 @@ mod security;
 
 pub use connection::VncClient;
 pub use connector::{VncConnector, VncSecurityPolicy};
+pub use security::ra2::VncServerKey;

src-tauri/vendor/vnc-rs/src/client/security/mod.rs

@@ -1 +1,3 @@
 pub(crate) mod des;
+
+pub(crate) mod ra2;

src-tauri/vendor/vnc-rs/src/client/security/ra2.rs

@@ -0,0 +1,854 @@
+use std::{
+    future::Future,
+    io,
+    pin::Pin,
+    sync::Arc,
+    task::{Context, Poll},
+};
+
+use aes::Aes256;
+use eax::{
+    aead::{generic_array::GenericArray, AeadInPlace, KeyInit},
+    Eax,
+};
+use rand::{rngs::OsRng, RngCore};
+use rsa::{traits::PublicKeyParts, BigUint, Pkcs1v15Encrypt, RsaPrivateKey, RsaPublicKey};
+use sha2::{Digest, Sha256};
+use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt, ReadBuf};
+
+use crate::{VncError, VncLimits, VncVersion};
+
+use super::super::auth::read_security_failure;
+
+type Aes256Eax = Eax<Aes256>;
+const RA2_RANDOM_BYTES: usize = 16;
+const RA2_HASH_BYTES: usize = 32;
+const RA2_MAC_BYTES: usize = 16;
+const CLIENT_RSA_BITS: usize = 2048;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct VncServerKey {
+    bits: u32,
+    encoded: Vec<u8>,
+}
+
+impl VncServerKey {
+    pub fn bits(&self) -> u32 {
+        self.bits
+    }
+
+    pub fn encoded(&self) -> &[u8] {
+        &self.encoded
+    }
+}
+
+pub(crate) type ServerKeyVerifyFuture =
+    Pin<Box<dyn Future<Output = Result<(), VncError>> + Send + 'static>>;
+pub(crate) type ServerKeyVerifier =
+    Arc<dyn Fn(VncServerKey) -> ServerKeyVerifyFuture + Send + Sync + 'static>;
+
+pub(crate) fn validate_credentials(username: &str, password: &str) -> Result<(), VncError> {
+    validate_credential("RA2 username", username)?;
+    validate_credential("RA2 password", password)
+}
+
+fn validate_credential(field: &'static str, value: &str) -> Result<(), VncError> {
+    let len = value.len();
+    if len > usize::from(u8::MAX) {
+        return Err(VncError::CredentialTooLong {
+            field,
+            actual: len,
+            limit: usize::from(u8::MAX),
+        });
+    }
+    Ok(())
+}
+
+pub(crate) async fn authenticate<S>(
+    mut stream: S,
+    username: String,
+    password: String,
+    verifier: ServerKeyVerifier,
+    limits: VncLimits,
+    version: VncVersion,
+) -> Result<Ra2Stream<S>, VncError>
+where
+    S: AsyncRead + AsyncWrite + Unpin,
+{
+    validate_credentials(&username, &password)?;
+
+    let (server_public_key, server_wire) = read_public_key(&mut stream, &limits).await?;
+    verifier(VncServerKey {
+        bits: u32::try_from(server_public_key.n().bits()).unwrap_or(u32::MAX),
+        encoded: server_wire.clone(),
+    })
+    .await?;
+
+    let mut rng = OsRng;
+    let client_private_key = RsaPrivateKey::new(&mut rng, CLIENT_RSA_BITS)
+        .map_err(|_| VncError::Ra2Crypto("failed to generate client RSA key"))?;
+    let client_public_key = RsaPublicKey::from(&client_private_key);
+    let client_wire = encode_public_key(&client_public_key)?;
+    stream.write_all(&client_wire).await?;
+
+    let encrypted_server_random_len = usize::from(stream.read_u16().await?);
+    let expected_server_random_len = client_private_key.size();
+    if encrypted_server_random_len != expected_server_random_len {
+        return Err(VncError::InvalidRa2EncryptedRandomLength {
+            actual: encrypted_server_random_len,
+            expected: expected_server_random_len,
+        });
+    }
+    let mut encrypted_server_random = vec![0; encrypted_server_random_len];
+    stream.read_exact(&mut encrypted_server_random).await?;
+    let server_random = client_private_key
+        .decrypt(Pkcs1v15Encrypt, &encrypted_server_random)
+        .map_err(|_| VncError::Ra2Crypto("failed to decrypt server random"))?;
+    if server_random.len() != RA2_RANDOM_BYTES {
+        return Err(VncError::InvalidRa2RandomLength(server_random.len()));
+    }
+
+    let mut client_random = [0_u8; RA2_RANDOM_BYTES];
+    rng.fill_bytes(&mut client_random);
+    let encrypted_client_random = server_public_key
+        .encrypt(&mut rng, Pkcs1v15Encrypt, &client_random)
+        .map_err(|_| VncError::Ra2Crypto("failed to encrypt client random"))?;
+    let encrypted_client_random_len =
+        u16::try_from(encrypted_client_random.len()).map_err(|_| VncError::LimitExceeded {
+            field: "RA2 encrypted client random",
+            actual: encrypted_client_random.len() as u64,
+            limit: u64::from(u16::MAX),
+        })?;
+    stream.write_u16(encrypted_client_random_len).await?;
+    stream.write_all(&encrypted_client_random).await?;
+
+    let client_session_key = sha256_concat(&server_random, &client_random);
+    let server_session_key = sha256_concat(&client_random, &server_random);
+    let expected_server_hash = sha256_concat(&server_wire, &client_wire);
+    let client_hash = sha256_concat(&client_wire, &server_wire);
+
+    let mut encrypted = Ra2Stream::new(
+        stream,
+        client_session_key,
+        server_session_key,
+        limits.max_ra2_record_bytes,
+    )?;
+
+    let mut server_hash = [0_u8; RA2_HASH_BYTES];
+    encrypted.read_exact(&mut server_hash).await?;
+    if server_hash != expected_server_hash {
+        return Err(VncError::Ra2ServerHashMismatch);
+    }
+    encrypted.write_all(&client_hash).await?;
+
+    let subtype = encrypted.read_u8().await?;
+    let mut credentials = Vec::with_capacity(username.len() + password.len() + 2);
+    match subtype {
+        1 => {
+            credentials.push(username.len() as u8);
+            credentials.extend_from_slice(username.as_bytes());
+        }
+        2 => credentials.push(0),
+        invalid => return Err(VncError::InvalidRa2Subtype(invalid)),
+    }
+    credentials.push(password.len() as u8);
+    credentials.extend_from_slice(password.as_bytes());
+    encrypted.write_all(&credentials).await?;
+
+    let result = encrypted.read_u32().await?;
+    match result {
+        0 => Ok(encrypted),
+        1 => {
+            if version == VncVersion::RFB38 {
+                let reason = read_security_failure(&mut encrypted, &limits).await?;
+                Err(VncError::SecurityFailure(reason))
+            } else {
+                Err(VncError::WrongPassword)
+            }
+        }
+        invalid => Err(VncError::InvalidSecurityResult(invalid)),
+    }
+}
+
+async fn read_public_key<S>(
+    stream: &mut S,
+    limits: &VncLimits,
+) -> Result<(RsaPublicKey, Vec<u8>), VncError>
+where
+    S: AsyncRead + Unpin,
+{
+    let bits = stream.read_u32().await?;
+    if bits < limits.min_ra2_key_bits || bits > limits.max_ra2_key_bits {
+        return Err(VncError::InvalidRa2KeyLength {
+            actual: bits,
+            min: limits.min_ra2_key_bits,
+            max: limits.max_ra2_key_bits,
+        });
+    }
+    let key_bytes_u32 = bits
+        .checked_add(7)
+        .ok_or(VncError::IntegerOverflow("RA2 key byte length"))?
+        / 8;
+    let key_bytes = usize::try_from(key_bytes_u32)
+        .map_err(|_| VncError::IntegerOverflow("RA2 key byte length"))?;
+    let mut modulus = vec![0_u8; key_bytes];
+    let mut exponent = vec![0_u8; key_bytes];
+    stream.read_exact(&mut modulus).await?;
+    stream.read_exact(&mut exponent).await?;
+
+    let public_key = RsaPublicKey::new(
+        BigUint::from_bytes_be(&modulus),
+        BigUint::from_bytes_be(&exponent),
+    )
+    .map_err(|_| VncError::InvalidRa2PublicKey)?;
+
+    let mut wire = Vec::with_capacity(4 + key_bytes * 2);
+    wire.extend_from_slice(&bits.to_be_bytes());
+    wire.extend_from_slice(&modulus);
+    wire.extend_from_slice(&exponent);
+    Ok((public_key, wire))
+}
+
+fn encode_public_key(key: &RsaPublicKey) -> Result<Vec<u8>, VncError> {
+    let bits = u32::try_from(key.n().bits()).map_err(|_| VncError::InvalidRa2PublicKey)?;
+    let key_bytes = usize::try_from(
+        bits.checked_add(7)
+            .ok_or(VncError::IntegerOverflow("RA2 key byte length"))?
+            / 8,
+    )
+    .map_err(|_| VncError::IntegerOverflow("RA2 key byte length"))?;
+    let modulus = key.n().to_bytes_be();
+    let exponent = key.e().to_bytes_be();
+    if modulus.len() > key_bytes || exponent.len() > key_bytes {
+        return Err(VncError::InvalidRa2PublicKey);
+    }
+
+    let mut wire = Vec::with_capacity(4 + key_bytes * 2);
+    wire.extend_from_slice(&bits.to_be_bytes());
+    wire.resize(4 + key_bytes - modulus.len(), 0);
+    wire.extend_from_slice(&modulus);
+    wire.resize(4 + key_bytes * 2 - exponent.len(), 0);
+    wire.extend_from_slice(&exponent);
+    Ok(wire)
+}
+
+fn sha256_concat(left: &[u8], right: &[u8]) -> [u8; RA2_HASH_BYTES] {
+    let mut hasher = Sha256::new();
+    hasher.update(left);
+    hasher.update(right);
+    hasher.finalize().into()
+}
+
+pub(crate) struct Ra2Stream<S> {
+    stream: S,
+    write_cipher: Aes256Eax,
+    read_cipher: Aes256Eax,
+    write_counter: [u8; 16],
+    read_counter: [u8; 16],
+    max_record_bytes: usize,
+    read_header: [u8; 2],
+    read_header_pos: usize,
+    read_body: Vec<u8>,
+    read_body_pos: usize,
+    read_plain: Vec<u8>,
+    read_plain_pos: usize,
+    write_pending: Vec<u8>,
+    write_pending_pos: usize,
+}
+
+impl<S> Ra2Stream<S> {
+    fn new(
+        stream: S,
+        write_key: [u8; 32],
+        read_key: [u8; 32],
+        max_record_bytes: usize,
+    ) -> Result<Self, VncError> {
+        if max_record_bytes == 0 || max_record_bytes > usize::from(u16::MAX) {
+            return Err(VncError::InvalidRa2RecordLimit(max_record_bytes));
+        }
+        let write_cipher = Aes256Eax::new_from_slice(&write_key)
+            .map_err(|_| VncError::Ra2Crypto("invalid client session key"))?;
+        let read_cipher = Aes256Eax::new_from_slice(&read_key)
+            .map_err(|_| VncError::Ra2Crypto("invalid server session key"))?;
+        Ok(Self {
+            stream,
+            write_cipher,
+            read_cipher,
+            write_counter: [0; 16],
+            read_counter: [0; 16],
+            max_record_bytes,
+            read_header: [0; 2],
+            read_header_pos: 0,
+            read_body: Vec::new(),
+            read_body_pos: 0,
+            read_plain: Vec::new(),
+            read_plain_pos: 0,
+            write_pending: Vec::new(),
+            write_pending_pos: 0,
+        })
+    }
+
+    fn decrypt_ready_record(&mut self) -> io::Result<()> {
+        let ciphertext_len = usize::from(u16::from_be_bytes(self.read_header));
+        let (ciphertext, tag_bytes) = self.read_body.split_at_mut(ciphertext_len);
+        let tag = GenericArray::clone_from_slice(tag_bytes);
+        self.read_cipher
+            .decrypt_in_place_detached(
+                GenericArray::from_slice(&self.read_counter),
+                &self.read_header,
+                ciphertext,
+                &tag,
+            )
+            .map_err(|_| {
+                io::Error::new(
+                    io::ErrorKind::InvalidData,
+                    "RA2 AES-EAX authentication failed",
+                )
+            })?;
+        increment_counter(&mut self.read_counter);
+        self.read_plain.clear();
+        self.read_plain.extend_from_slice(ciphertext);
+        self.read_plain_pos = 0;
+        self.read_header_pos = 0;
+        self.read_body.clear();
+        self.read_body_pos = 0;
+        Ok(())
+    }
+
+    fn prepare_write_record(&mut self, plaintext: &[u8]) -> io::Result<usize> {
+        let len = plaintext.len().min(self.max_record_bytes);
+        let header = (len as u16).to_be_bytes();
+        let mut ciphertext = plaintext[..len].to_vec();
+        let tag = self
+            .write_cipher
+            .encrypt_in_place_detached(
+                GenericArray::from_slice(&self.write_counter),
+                &header,
+                &mut ciphertext,
+            )
+            .map_err(|_| io::Error::other("RA2 AES-EAX encryption failed"))?;
+        increment_counter(&mut self.write_counter);
+
+        self.write_pending.clear();
+        self.write_pending.reserve(2 + len + RA2_MAC_BYTES);
+        self.write_pending.extend_from_slice(&header);
+        self.write_pending.extend_from_slice(&ciphertext);
+        self.write_pending.extend_from_slice(&tag);
+        self.write_pending_pos = 0;
+        Ok(len)
+    }
+
+    fn poll_drain_write_pending(&mut self, cx: &mut Context<'_>) -> Poll<io::Result<()>>
+    where
+        S: AsyncWrite + Unpin,
+    {
+        while self.write_pending_pos < self.write_pending.len() {
+            let written = match Pin::new(&mut self.stream)
+                .poll_write(cx, &self.write_pending[self.write_pending_pos..])
+            {
+                Poll::Pending => return Poll::Pending,
+                Poll::Ready(Ok(0)) => {
+                    return Poll::Ready(Err(io::Error::new(
+                        io::ErrorKind::WriteZero,
+                        "failed to write RA2 record",
+                    )));
+                }
+                Poll::Ready(Ok(written)) => written,
+                Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+            };
+            self.write_pending_pos += written;
+        }
+        self.write_pending.clear();
+        self.write_pending_pos = 0;
+        Poll::Ready(Ok(()))
+    }
+}
+
+impl<S> AsyncRead for Ra2Stream<S>
+where
+    S: AsyncRead + AsyncWrite + Unpin,
+{
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        output: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        let this = self.get_mut();
+        loop {
+            if this.read_plain_pos < this.read_plain.len() {
+                let remaining = &this.read_plain[this.read_plain_pos..];
+                let count = remaining.len().min(output.remaining());
+                output.put_slice(&remaining[..count]);
+                this.read_plain_pos += count;
+                if this.read_plain_pos == this.read_plain.len() {
+                    this.read_plain.clear();
+                    this.read_plain_pos = 0;
+                }
+                return Poll::Ready(Ok(()));
+            }
+            if output.remaining() == 0 {
+                return Poll::Ready(Ok(()));
+            }
+            if !this.write_pending.is_empty() {
+                match this.poll_drain_write_pending(cx) {
+                    Poll::Pending => return Poll::Pending,
+                    Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+                    Poll::Ready(Ok(())) => {}
+                }
+            }
+
+            if this.read_header_pos < this.read_header.len() {
+                let start = this.read_header_pos;
+                let mut buffer = ReadBuf::new(&mut this.read_header[start..]);
+                match Pin::new(&mut this.stream).poll_read(cx, &mut buffer) {
+                    Poll::Pending => return Poll::Pending,
+                    Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+                    Poll::Ready(Ok(())) => {
+                        let read = buffer.filled().len();
+                        if read == 0 {
+                            if this.read_header_pos == 0 {
+                                return Poll::Ready(Ok(()));
+                            }
+                            return Poll::Ready(Err(io::Error::new(
+                                io::ErrorKind::UnexpectedEof,
+                                "truncated RA2 record header",
+                            )));
+                        }
+                        this.read_header_pos += read;
+                        if this.read_header_pos < this.read_header.len() {
+                            continue;
+                        }
+                        let ciphertext_len = usize::from(u16::from_be_bytes(this.read_header));
+                        if ciphertext_len > this.max_record_bytes {
+                            return Poll::Ready(Err(io::Error::new(
+                                io::ErrorKind::InvalidData,
+                                format!(
+                                    "RA2 record exceeds configured limit: {ciphertext_len} > {}",
+                                    this.max_record_bytes
+                                ),
+                            )));
+                        }
+                        this.read_body.resize(ciphertext_len + RA2_MAC_BYTES, 0);
+                        this.read_body_pos = 0;
+                    }
+                }
+            }
+
+            if this.read_body_pos < this.read_body.len() {
+                let start = this.read_body_pos;
+                let mut buffer = ReadBuf::new(&mut this.read_body[start..]);
+                match Pin::new(&mut this.stream).poll_read(cx, &mut buffer) {
+                    Poll::Pending => return Poll::Pending,
+                    Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+                    Poll::Ready(Ok(())) => {
+                        let read = buffer.filled().len();
+                        if read == 0 {
+                            return Poll::Ready(Err(io::Error::new(
+                                io::ErrorKind::UnexpectedEof,
+                                "truncated RA2 encrypted record",
+                            )));
+                        }
+                        this.read_body_pos += read;
+                        if this.read_body_pos < this.read_body.len() {
+                            continue;
+                        }
+                    }
+                }
+            }
+
+            if let Err(error) = this.decrypt_ready_record() {
+                return Poll::Ready(Err(error));
+            }
+        }
+    }
+}
+
+impl<S> AsyncWrite for Ra2Stream<S>
+where
+    S: AsyncWrite + Unpin,
+{
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        input: &[u8],
+    ) -> Poll<io::Result<usize>> {
+        let this = self.get_mut();
+        if !this.write_pending.is_empty() {
+            match this.poll_drain_write_pending(cx) {
+                Poll::Pending => return Poll::Pending,
+                Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+                Poll::Ready(Ok(())) => {}
+            }
+        }
+        if input.is_empty() {
+            return Poll::Ready(Ok(0));
+        }
+        let consumed = match this.prepare_write_record(input) {
+            Ok(consumed) => consumed,
+            Err(error) => return Poll::Ready(Err(error)),
+        };
+        let written = match Pin::new(&mut this.stream)
+            .poll_write(cx, &this.write_pending[this.write_pending_pos..])
+        {
+            Poll::Pending => return Poll::Ready(Ok(consumed)),
+            Poll::Ready(Ok(0)) => {
+                return Poll::Ready(Err(io::Error::new(
+                    io::ErrorKind::WriteZero,
+                    "failed to write RA2 record",
+                )));
+            }
+            Poll::Ready(Ok(written)) => written,
+            Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+        };
+        this.write_pending_pos += written;
+        if this.write_pending_pos == this.write_pending.len() {
+            this.write_pending.clear();
+            this.write_pending_pos = 0;
+        }
+        Poll::Ready(Ok(consumed))
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        let this = self.get_mut();
+        if !this.write_pending.is_empty() {
+            match this.poll_drain_write_pending(cx) {
+                Poll::Pending => return Poll::Pending,
+                Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+                Poll::Ready(Ok(())) => {}
+            }
+        }
+        Pin::new(&mut this.stream).poll_flush(cx)
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+        let this = self.get_mut();
+        if !this.write_pending.is_empty() {
+            match this.poll_drain_write_pending(cx) {
+                Poll::Pending => return Poll::Pending,
+                Poll::Ready(Err(error)) => return Poll::Ready(Err(error)),
+                Poll::Ready(Ok(())) => {}
+            }
+        }
+        Pin::new(&mut this.stream).poll_shutdown(cx)
+    }
+}
+
+fn increment_counter(counter: &mut [u8; 16]) {
+    for byte in counter {
+        let (next, overflow) = byte.overflowing_add(1);
+        *byte = next;
+        if !overflow {
+            break;
+        }
+    }
+}
+
+#[cfg(test)]
+async fn establish_test_encryption<S>(
+    mut stream: S,
+    limits: VncLimits,
+    corrupt_server_hash: bool,
+) -> Ra2Stream<S>
+where
+    S: AsyncRead + AsyncWrite + Unpin,
+{
+    let mut rng = OsRng;
+    let server_private_key = RsaPrivateKey::new(&mut rng, CLIENT_RSA_BITS).unwrap();
+    let server_public_key = RsaPublicKey::from(&server_private_key);
+    let server_wire = encode_public_key(&server_public_key).unwrap();
+    stream.write_all(&server_wire).await.unwrap();
+
+    let (client_public_key, client_wire) = read_public_key(&mut stream, &limits).await.unwrap();
+    let server_random = [0x31_u8; RA2_RANDOM_BYTES];
+    let encrypted_server_random = client_public_key
+        .encrypt(&mut rng, Pkcs1v15Encrypt, &server_random)
+        .unwrap();
+    stream
+        .write_u16(encrypted_server_random.len() as u16)
+        .await
+        .unwrap();
+    stream.write_all(&encrypted_server_random).await.unwrap();
+
+    let encrypted_client_random_len = usize::from(stream.read_u16().await.unwrap());
+    let mut encrypted_client_random = vec![0_u8; encrypted_client_random_len];
+    stream
+        .read_exact(&mut encrypted_client_random)
+        .await
+        .unwrap();
+    let client_random = server_private_key
+        .decrypt(Pkcs1v15Encrypt, &encrypted_client_random)
+        .unwrap();
+    assert_eq!(client_random.len(), RA2_RANDOM_BYTES);
+
+    let client_session_key = sha256_concat(&server_random, &client_random);
+    let server_session_key = sha256_concat(&client_random, &server_random);
+    let mut server_hash = sha256_concat(&server_wire, &client_wire);
+    let expected_client_hash = sha256_concat(&client_wire, &server_wire);
+    let mut encrypted = Ra2Stream::new(
+        stream,
+        server_session_key,
+        client_session_key,
+        limits.max_ra2_record_bytes,
+    )
+    .unwrap();
+
+    if corrupt_server_hash {
+        server_hash[0] ^= 0x80;
+    }
+    encrypted.write_all(&server_hash).await.unwrap();
+    if corrupt_server_hash {
+        return encrypted;
+    }
+    let mut client_hash = [0_u8; RA2_HASH_BYTES];
+    encrypted.read_exact(&mut client_hash).await.unwrap();
+    assert_eq!(client_hash, expected_client_hash);
+    encrypted
+}
+
+#[cfg(test)]
+pub(crate) async fn accept_test_handshake<S>(
+    stream: S,
+    subtype: u8,
+    expected_username: &str,
+    expected_password: &str,
+    limits: VncLimits,
+) -> Ra2Stream<S>
+where
+    S: AsyncRead + AsyncWrite + Unpin,
+{
+    let mut encrypted = establish_test_encryption(stream, limits, false).await;
+
+    encrypted.write_u8(subtype).await.unwrap();
+    let username_len = usize::from(encrypted.read_u8().await.unwrap());
+    let mut username = vec![0_u8; username_len];
+    encrypted.read_exact(&mut username).await.unwrap();
+    let password_len = usize::from(encrypted.read_u8().await.unwrap());
+    let mut password = vec![0_u8; password_len];
+    encrypted.read_exact(&mut password).await.unwrap();
+    assert_eq!(username, expected_username.as_bytes());
+    assert_eq!(password, expected_password.as_bytes());
+    encrypted.write_u32(0).await.unwrap();
+    encrypted
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[derive(Default)]
+    struct PartialThenPendingWriter {
+        bytes: Vec<u8>,
+        write_polls: usize,
+    }
+
+    impl AsyncWrite for PartialThenPendingWriter {
+        fn poll_write(
+            mut self: Pin<&mut Self>,
+            cx: &mut Context<'_>,
+            input: &[u8],
+        ) -> Poll<io::Result<usize>> {
+            self.write_polls += 1;
+            match self.write_polls {
+                1 => {
+                    let written = input.len().min(3);
+                    self.bytes.extend_from_slice(&input[..written]);
+                    Poll::Ready(Ok(written))
+                }
+                2 => {
+                    cx.waker().wake_by_ref();
+                    Poll::Pending
+                }
+                _ => {
+                    self.bytes.extend_from_slice(input);
+                    Poll::Ready(Ok(input.len()))
+                }
+            }
+        }
+
+        fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+            Poll::Ready(Ok(()))
+        }
+
+        fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<()>> {
+            Poll::Ready(Ok(()))
+        }
+    }
+
+    fn paired_streams<S1, S2>(
+        left: S1,
+        right: S2,
+        max_record_bytes: usize,
+    ) -> (Ra2Stream<S1>, Ra2Stream<S2>) {
+        let left_to_right = [0x11; 32];
+        let right_to_left = [0x22; 32];
+        (
+            Ra2Stream::new(left, left_to_right, right_to_left, max_record_bytes).unwrap(),
+            Ra2Stream::new(right, right_to_left, left_to_right, max_record_bytes).unwrap(),
+        )
+    }
+
+    #[test]
+    fn credentials_use_utf8_byte_limits() {
+        assert!(validate_credentials("用户", "密码").is_ok());
+        let error = validate_credentials(&"é".repeat(128), "password").unwrap_err();
+        assert!(matches!(
+            error,
+            VncError::CredentialTooLong {
+                field: "RA2 username",
+                actual: 256,
+                limit: 255
+            }
+        ));
+    }
+
+    #[test]
+    fn encrypted_stream_backpressure_does_not_consume_replacement_input() {
+        let writer = PartialThenPendingWriter::default();
+        let mut stream = Ra2Stream::new(writer, [0x55; 32], [0x66; 32], 64).unwrap();
+        let waker = futures::task::noop_waker_ref();
+        let mut cx = Context::from_waker(waker);
+
+        assert!(matches!(
+            Pin::new(&mut stream).poll_write(&mut cx, b"first"),
+            Poll::Ready(Ok(5))
+        ));
+        assert!(matches!(
+            Pin::new(&mut stream).poll_write(&mut cx, b"cancelled"),
+            Poll::Pending
+        ));
+        assert!(matches!(
+            Pin::new(&mut stream).poll_write(&mut cx, b"x"),
+            Poll::Ready(Ok(1))
+        ));
+        assert!(matches!(
+            Pin::new(&mut stream).poll_flush(&mut cx),
+            Poll::Ready(Ok(()))
+        ));
+
+        let first_record_len = 2 + 5 + RA2_MAC_BYTES;
+        let bytes = &stream.stream.bytes;
+        assert_eq!(bytes.len(), first_record_len + 2 + 1 + RA2_MAC_BYTES);
+        assert_eq!(&bytes[..2], &5_u16.to_be_bytes());
+        assert_eq!(
+            &bytes[first_record_len..first_record_len + 2],
+            &1_u16.to_be_bytes()
+        );
+    }
+
+    #[tokio::test]
+    async fn rejects_out_of_range_server_rsa_key_before_allocation() {
+        let mut input = &9_000_u32.to_be_bytes()[..];
+        let error = read_public_key(&mut input, &VncLimits::default())
+            .await
+            .unwrap_err();
+        assert!(matches!(
+            error,
+            VncError::InvalidRa2KeyLength {
+                actual: 9_000,
+                min: 1_024,
+                max: 8_192
+            }
+        ));
+    }
+
+    #[tokio::test]
+    async fn authenticate_rejects_server_hash_mismatch() {
+        let (client, server) = tokio::io::duplex(16 * 1024);
+        let limits = VncLimits::default();
+        let server_task = tokio::spawn(async move {
+            let _encrypted = establish_test_encryption(server, limits, true).await;
+        });
+        let verifier: ServerKeyVerifier = Arc::new(|_| Box::pin(async { Ok(()) }));
+
+        let error = match authenticate(
+            client,
+            "pi".to_string(),
+            "raspberry".to_string(),
+            verifier,
+            limits,
+            VncVersion::RFB38,
+        )
+        .await
+        {
+            Ok(_) => panic!("corrupted server key hash must fail closed"),
+            Err(error) => error,
+        };
+        assert!(matches!(error, VncError::Ra2ServerHashMismatch));
+        server_task.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn authenticate_rejects_unknown_subtype() {
+        let (client, server) = tokio::io::duplex(16 * 1024);
+        let limits = VncLimits::default();
+        let server_task = tokio::spawn(async move {
+            let mut encrypted = establish_test_encryption(server, limits, false).await;
+            encrypted.write_u8(3).await.unwrap();
+        });
+        let verifier: ServerKeyVerifier = Arc::new(|_| Box::pin(async { Ok(()) }));
+
+        let error = match authenticate(
+            client,
+            "pi".to_string(),
+            "raspberry".to_string(),
+            verifier,
+            limits,
+            VncVersion::RFB38,
+        )
+        .await
+        {
+            Ok(_) => panic!("unknown RA2 subtype must fail closed"),
+            Err(error) => error,
+        };
+        assert!(matches!(error, VncError::InvalidRa2Subtype(3)));
+        server_task.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn encrypted_stream_splits_and_coalesces_independently_of_rfb_reads() {
+        let (left_io, right_io) = tokio::io::duplex(4096);
+        let (mut left, mut right) = paired_streams(left_io, right_io, 5);
+
+        let sender = tokio::spawn(async move {
+            left.write_all(b"abcdefgh").await.unwrap();
+            left.write_all(b"ijklmnop").await.unwrap();
+            left
+        });
+
+        let mut first = [0_u8; 3];
+        right.read_exact(&mut first).await.unwrap();
+        assert_eq!(&first, b"abc");
+        let mut rest = [0_u8; 13];
+        right.read_exact(&mut rest).await.unwrap();
+        assert_eq!(&rest, b"defghijklmnop");
+
+        let mut left = sender.await.unwrap();
+        right.write_all(b"reply-one").await.unwrap();
+        right.write_all(b"reply-two").await.unwrap();
+        let mut reply = [0_u8; 18];
+        left.read_exact(&mut reply).await.unwrap();
+        assert_eq!(&reply, b"reply-onereply-two");
+    }
+
+    #[tokio::test]
+    async fn encrypted_stream_rejects_bad_mac() {
+        let (mut raw_writer, raw_reader) = tokio::io::duplex(128);
+        let key = [0x44; 32];
+        let mut reader = Ra2Stream::new(raw_reader, [0x33; 32], key, 64).unwrap();
+        let cipher = Aes256Eax::new_from_slice(&key).unwrap();
+        let header = 3_u16.to_be_bytes();
+        let mut ciphertext = b"bad".to_vec();
+        let tag = cipher
+            .encrypt_in_place_detached(GenericArray::from_slice(&[0; 16]), &header, &mut ciphertext)
+            .unwrap();
+        raw_writer.write_all(&header).await.unwrap();
+        raw_writer.write_all(&ciphertext).await.unwrap();
+        let mut bad_tag = tag.to_vec();
+        bad_tag[0] ^= 0x80;
+        raw_writer.write_all(&bad_tag).await.unwrap();
+
+        let mut output = [0_u8; 3];
+        let error = reader.read_exact(&mut output).await.unwrap_err();
+        assert_eq!(error.kind(), io::ErrorKind::InvalidData);
+    }
+}

src-tauri/vendor/vnc-rs/src/error.rs

@@ -19,6 +19,32 @@ pub enum VncError {
     RequiredSecurityTypeUnavailable(&'static str),
     #[error("Wrong password")]
     WrongPassword,
+    #[error("VNC credential is too long for {field}: {actual} > {limit} bytes")]
+    CredentialTooLong {
+        field: &'static str,
+        actual: usize,
+        limit: usize,
+    },
+    #[error("RA2 server key length is outside the supported range: {actual} bits (expected {min}..={max})")]
+    InvalidRa2KeyLength { actual: u32, min: u32, max: u32 },
+    #[error("Invalid RA2 RSA public key")]
+    InvalidRa2PublicKey,
+    #[error("Invalid RA2 encrypted random length: {actual} bytes, expected {expected}")]
+    InvalidRa2EncryptedRandomLength { actual: usize, expected: usize },
+    #[error("Invalid RA2 decrypted random length: {0} bytes")]
+    InvalidRa2RandomLength(usize),
+    #[error("RA2 server public-key hash verification failed")]
+    Ra2ServerHashMismatch,
+    #[error("Unknown RA2 authentication subtype: {0}")]
+    InvalidRa2Subtype(u8),
+    #[error("RA2 server key verification callback is required")]
+    Ra2ServerKeyVerifierRequired,
+    #[error("RA2 server key was rejected: {0}")]
+    Ra2ServerKeyRejected(String),
+    #[error("Invalid RA2 record size limit: {0}")]
+    InvalidRa2RecordLimit(usize),
+    #[error("RA2 cryptographic operation failed: {0}")]
+    Ra2Crypto(&'static str),
     #[error("Server rejected the connection: {0}")]
     SecurityFailure(String),
     #[error("Protocol limit exceeded for {field}: {actual} > {limit}")]

src-tauri/vendor/vnc-rs/src/lib.rs

@@ -217,7 +217,7 @@ pub mod event;
 pub mod limits;
 
 pub use client::VncClient;
-pub use client::{VncConnector, VncSecurityPolicy};
+pub use client::{VncConnector, VncSecurityPolicy, VncServerKey};
 pub use config::*;
 pub use error::*;
 pub use event::*;

src-tauri/vendor/vnc-rs/src/limits.rs

@@ -3,6 +3,9 @@
 pub struct VncLimits {
     pub max_server_name_bytes: usize,
     pub max_failure_reason_bytes: usize,
+    pub min_ra2_key_bits: u32,
+    pub max_ra2_key_bits: u32,
+    pub max_ra2_record_bytes: usize,
     pub max_clipboard_bytes: usize,
     pub max_framebuffer_width: u16,
     pub max_framebuffer_height: u16,
@@ -18,6 +21,9 @@ impl Default for VncLimits {
         Self {
             max_server_name_bytes: 64 * 1024,
             max_failure_reason_bytes: 64 * 1024,
+            min_ra2_key_bits: 1_024,
+            max_ra2_key_bits: 8_192,
+            max_ra2_record_bytes: usize::from(u16::MAX),
             max_clipboard_bytes: 16 * 1024 * 1024,
             max_framebuffer_width: 16_384,
             max_framebuffer_height: 16_384,

src/App.tsx

@@ -7,6 +7,7 @@ import AppPanelContent from "./components/app/AppPanelContent";
 import ActivityBarResetDialog from "./components/dialog/app/ActivityBarResetDialog";
 import AppOverlayDialogs from "./components/dialog/app/AppOverlayDialogs";
 import { McpApprovalHost } from "./components/dialog/app/McpApprovalHost";
+import type { VncServerKeyVerifyRequest } from "./components/dialog/connections/VncServerKeyVerifyDialog";
 import type { RdpCertificateVerifyRequest } from "./components/dialog/connections/RdpCertificateVerifyDialog";
 import type { DockerSudoPasswordRequest } from "./components/dialog/docker/DockerSudoPasswordDialog";
 import type { QuickSwitcherSession } from "./components/dialog/terminal/SessionQuickSwitcherDialog";
@@ -312,6 +313,7 @@ function App() {
   const [rdpCertificateRequests, setRdpCertificateRequests] = useState<
     RdpCertificateVerifyRequest[]
   >([]);
+  const [vncServerKeyRequests, setVncServerKeyRequests] = useState<VncServerKeyVerifyRequest[]>([]);
   const modalChildWindowCount = useModalChildWindows();
 
   // Idle auto-lock
@@ -486,6 +488,7 @@ function App() {
     removeSecurityPrompt,
     setDockerSudoPasswordRequest,
     setRdpCertificateRequests,
+    setVncServerKeyRequests,
     handleConnectAfterEdit,
     handleOpenPanel,
   });
@@ -2953,7 +2956,8 @@ function App() {
         Boolean(activeOtpRequest) ||
         Boolean(activeSshAuthRequest) ||
         Boolean(dockerSudoPasswordRequest) ||
-        rdpCertificateRequests.length > 0
+        rdpCertificateRequests.length > 0 ||
+        vncServerKeyRequests.length > 0
       ) {
         return;
       }
@@ -2989,6 +2993,7 @@ function App() {
     pendingFileDocumentClose,
     postLoginConfirm,
     rdpCertificateRequests.length,
+    vncServerKeyRequests.length,
     showAbout,
     showActivityBarResetConfirm,
     showQuitConfirm,
@@ -3369,6 +3374,11 @@ function App() {
             setRdpCertificateRequests((current) =>
               current.filter((item) => item.requestId !== requestId),
             ),
+          vncServerKeyVerifyRequest: vncServerKeyRequests[0] ?? null,
+          onVncServerKeyVerifyDone: (requestId) =>
+            setVncServerKeyRequests((current) =>
+              current.filter((item) => item.requestId !== requestId),
+            ),
           modalChildWindowCount,
           locked: isLocked,
           hasMasterPassword: !!appSettings.security.master_password,

src/components/app/AppLayout.tsx

@@ -21,6 +21,8 @@ import type { OtpRequest } from "@/components/dialog/connections/OtpDialog";
 import { OtpDialog } from "@/components/dialog/connections/OtpDialog";
 import type { RdpCertificateVerifyRequest } from "@/components/dialog/connections/RdpCertificateVerifyDialog";
 import { RdpCertificateVerifyDialog } from "@/components/dialog/connections/RdpCertificateVerifyDialog";
+import type { VncServerKeyVerifyRequest } from "@/components/dialog/connections/VncServerKeyVerifyDialog";
+import { VncServerKeyVerifyDialog } from "@/components/dialog/connections/VncServerKeyVerifyDialog";
 import type { SshAuthRequest } from "@/components/dialog/connections/SshAuthDialog";
 import { SshAuthDialog } from "@/components/dialog/connections/SshAuthDialog";
 import type { SshAgentAuthRequest } from "@/components/dialog/connections/SshAgentAuthDialog";
@@ -166,6 +168,8 @@ interface AppLayoutProps {
     onHostKeyVerifyDone: (requestId: string) => void;
     rdpCertificateVerifyRequest: RdpCertificateVerifyRequest | null;
     onRdpCertificateVerifyDone: (requestId: string) => void;
+    vncServerKeyVerifyRequest: VncServerKeyVerifyRequest | null;
+    onVncServerKeyVerifyDone: (requestId: string) => void;
     modalChildWindowCount: number;
     locked: boolean;
     hasMasterPassword: boolean;
@@ -680,6 +684,10 @@ export default function AppLayout({
           request={dialogs.rdpCertificateVerifyRequest}
           onDone={dialogs.onRdpCertificateVerifyDone}
         />
+        <VncServerKeyVerifyDialog
+          request={dialogs.vncServerKeyVerifyRequest}
+          onDone={dialogs.onVncServerKeyVerifyDone}
+        />
         <TransferDuplicateDialog />
 
         {dialogs.modalChildWindowCount > 0 && (

src/components/dialog/connections/VncServerKeyVerifyDialog.tsx

@@ -0,0 +1,149 @@
+import { ShieldAlert, ShieldQuestion } from "lucide-react";
+import { useState } from "react";
+import { useTranslation } from "react-i18next";
+import { Button } from "@/components/ui/button";
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from "@/components/ui/dialog";
+import { invoke } from "@/lib/invoke";
+import { logger } from "@/lib/logger";
+
+export interface VncServerKeyVerifyRequest {
+  requestId: string;
+  sessionId: string;
+  host: string;
+  port: number;
+  fingerprint: string;
+  keyBits: number;
+  knownHostStatus: "match" | "changed" | "unknown" | string;
+  targetWindowLabel?: string | null;
+}
+
+interface VncServerKeyVerifyDialogProps {
+  request: VncServerKeyVerifyRequest | null;
+  onDone: (requestId: string) => void;
+}
+
+export function VncServerKeyVerifyDialog({
+  request,
+  onDone,
+}: VncServerKeyVerifyDialogProps) {
+  const { t } = useTranslation();
+  const [submitting, setSubmitting] = useState(false);
+  const changed = request?.knownHostStatus === "changed";
+
+  const respond = async (accepted: boolean) => {
+    if (!request || submitting) return;
+    setSubmitting(true);
+    try {
+      await invoke("respond_vnc_server_key", {
+        requestId: request.requestId,
+        accepted,
+      });
+      logger.info({
+        domain: "security.flow",
+        event: accepted
+          ? "vnc_server_key.user_accepted"
+          : "vnc_server_key.user_rejected",
+        message: accepted
+          ? "User accepted VNC server key"
+          : "User rejected VNC server key",
+        ids: { request_id: request.requestId, session_id: request.sessionId },
+      });
+    } catch (error) {
+      logger.error({
+        domain: "security.flow",
+        event: "vnc_server_key.response_failed",
+        message: "Failed to send VNC server key response",
+        ids: { request_id: request.requestId, session_id: request.sessionId },
+        error,
+      });
+    }
+    setSubmitting(false);
+    onDone(request.requestId);
+  };
+
+  return (
+    <Dialog
+      disablePointerDismissal
+      open={!!request}
+      onOpenChange={(open) => {
+        if (!open) void respond(false);
+      }}
+    >
+      <DialogContent className="max-w-md">
+        <DialogHeader>
+          <DialogTitle className="flex items-center gap-2 text-sm">
+            {changed ? (
+              <ShieldAlert className="h-4 w-4 text-destructive" />
+            ) : (
+              <ShieldQuestion className="h-4 w-4 text-yellow-500" />
+            )}
+            {t("settings.vncServerKeyVerifyTitle")}
+          </DialogTitle>
+          <DialogDescription className="text-xs">
+            {changed
+              ? t("settings.vncServerKeyVerifyChanged")
+              : t("settings.vncServerKeyVerifyNew")}
+          </DialogDescription>
+        </DialogHeader>
+
+        <div className="space-y-2 overflow-hidden py-2 text-xs">
+          <div className="grid grid-cols-[auto_minmax(0,1fr)] gap-x-3 gap-y-1">
+            <span className="text-muted-foreground">
+              {t("settings.hostKeyVerifyHost")}
+            </span>
+            <span
+              className="truncate font-mono"
+              title={`${request?.host}:${request?.port}`}
+            >
+              {request?.host}:{request?.port}
+            </span>
+            <span className="text-muted-foreground">
+              {t("settings.hostKeyVerifyFingerprint")}
+            </span>
+            <span className="break-all font-mono select-all">
+              {request?.fingerprint}
+            </span>
+            <span className="text-muted-foreground">
+              {t("settings.vncServerKeyBits")}
+            </span>
+            <span className="font-mono">{request?.keyBits}</span>
+          </div>
+
+          {changed && (
+            <div className="rounded-md border border-destructive/50 bg-destructive/10 p-2 text-[0.6875rem] text-destructive">
+              {t("settings.vncServerKeyVerifyWarning")}
+            </div>
+          )}
+        </div>
+
+        <DialogFooter className="gap-2 sm:gap-0">
+          <Button
+            variant="ghost"
+            size="sm"
+            className="text-xs"
+            onClick={() => void respond(false)}
+            disabled={submitting}
+          >
+            {t("settings.hostKeyVerifyReject")}
+          </Button>
+          <Button
+            size="sm"
+            className="text-xs"
+            variant={changed ? "destructive" : "default"}
+            onClick={() => void respond(true)}
+            disabled={submitting}
+          >
+            {t("settings.vncServerKeyAccept")}
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}

src/components/sessions/VncForm.test.tsx

@@ -15,6 +15,8 @@ function props() {
     setHost: vi.fn(),
     port: 5900,
     setPort: vi.fn(),
+    username: "pi",
+    setUsername: vi.fn(),
     passwordId: "",
     setPasswordId: vi.fn(),
     password: "",
@@ -50,10 +52,18 @@ describe("VncForm", () => {
     invokeMock.mockResolvedValue([]);
   });
 
-  it("uses the standard VNC port and explains the classic password limit", () => {
+  it("shows the RA2 username in auto mode without applying the classic password hint", () => {
     render(<VncForm {...props()} />);
 
     expect(screen.getByDisplayValue("5900")).not.toBeNull();
+    expect(screen.getByDisplayValue("pi")).not.toBeNull();
+    expect(screen.getByText("dialog.vncUsernameHint")).not.toBeNull();
+    expect(screen.queryByText("dialog.vncPasswordLimit")).toBeNull();
+  });
+
+  it("shows the 8-byte password hint only for classic VNC authentication", () => {
+    render(<VncForm {...props()} securityMode="vnc-auth" />);
+
     expect(screen.getByText("dialog.vncPasswordLimit")).not.toBeNull();
   });
 

src/components/sessions/VncForm.tsx

@@ -28,6 +28,8 @@ interface VncFormProps {
   setHost: (value: string) => void;
   port: number;
   setPort: (value: number) => void;
+  username: string;
+  setUsername: (value: string) => void;
   passwordId: string;
   setPasswordId: (value: string) => void;
   password: string;
@@ -69,6 +71,8 @@ export function VncForm({
   setHost,
   port,
   setPort,
+  username,
+  setUsername,
   passwordId,
   setPasswordId,
   password,
@@ -181,6 +185,21 @@ export function VncForm({
         <Label className="text-xs font-medium text-foreground/80">
           {t("dialog.authentication")}
         </Label>
+        <div className="mt-1">
+          <Label className="text-xs font-medium text-foreground/80">{t("dialog.username")}</Label>
+          <Input
+            className="mt-1 h-8 text-xs"
+            value={username}
+            disabled={securityMode === "none"}
+            onChange={(event) => setUsername(event.target.value)}
+            placeholder={t("dialog.vncUsernamePlaceholder")}
+          />
+          {securityMode === "auto" ? (
+            <p className="mt-1 text-[0.6875rem] text-muted-foreground">
+              {t("dialog.vncUsernameHint")}
+            </p>
+          ) : null}
+        </div>
         <Tabs
           value={passwordSource}
           onValueChange={(value) => {
@@ -253,9 +272,11 @@ export function VncForm({
                 </>
               ) : null}
             </div>
+            {securityMode === "vnc-auth" ? (
               <p className="mt-1 text-[0.6875rem] text-muted-foreground">
                 {t("dialog.vncPasswordLimit")}
               </p>
+            ) : null}
           </TabsContent>
           <TabsContent value="saved" className="mt-3 border-0 outline-none">
             <Select

src/hooks/useAppWindowEvents.ts

@@ -3,6 +3,7 @@ import { type Dispatch, type SetStateAction, useEffect, useRef } from "react";
 import { toast } from "sonner";
 import type { HostKeyVerifyRequest } from "@/components/dialog/connections/HostKeyVerifyDialog";
 import type { OtpRequest } from "@/components/dialog/connections/OtpDialog";
+import type { VncServerKeyVerifyRequest } from "@/components/dialog/connections/VncServerKeyVerifyDialog";
 import type { RdpCertificateVerifyRequest } from "@/components/dialog/connections/RdpCertificateVerifyDialog";
 import type { SshAgentAuthRequest } from "@/components/dialog/connections/SshAgentAuthDialog";
 import type { SshAuthRequest } from "@/components/dialog/connections/SshAuthDialog";
@@ -25,6 +26,7 @@ interface AppWindowEventsOptions
     > {
   setTerminalWindows: Dispatch<SetStateAction<TerminalWindowNode | null>>;
   setDockerSudoPasswordRequest: Dispatch<SetStateAction<DockerSudoPasswordRequest | null>>;
+  setVncServerKeyRequests: Dispatch<SetStateAction<VncServerKeyVerifyRequest[]>>;
   setRdpCertificateRequests: Dispatch<SetStateAction<RdpCertificateVerifyRequest[]>>;
   handleConnectAfterEdit: (payload: SessionConnectAfterEditPayload) => Promise<void>;
   handleOpenPanel: (panelId: "syncBackupHistory") => void;
@@ -38,6 +40,7 @@ export function useAppWindowEvents({
   removeSecurityPrompt,
   setDockerSudoPasswordRequest,
   setRdpCertificateRequests,
+  setVncServerKeyRequests,
   handleConnectAfterEdit,
   handleOpenPanel,
 }: AppWindowEventsOptions) {
@@ -176,6 +179,16 @@ export function useAppWindowEvents({
       }),
     );
 
+    unsubs.push(
+      listen<VncServerKeyVerifyRequest>("vnc-server-key-verify", (event) => {
+        if (!eventTargetsCurrentWindow(event.payload.targetWindowLabel)) return;
+        setVncServerKeyRequests((current) => {
+          if (current.some((item) => item.requestId === event.payload.requestId)) return current;
+          return [...current, event.payload];
+        });
+      }),
+    );
+
     unsubs.push(
       listen<{
         requestId: string;
@@ -218,6 +231,7 @@ export function useAppWindowEvents({
     removeSecurityPrompt,
     setDockerSudoPasswordRequest,
     setRdpCertificateRequests,
+  setVncServerKeyRequests,
     handleConnectAfterEdit,
   ]);
 

src/i18n/locales/en.json

@@ -871,6 +871,8 @@
     "vncSecurityNone": "None",
     "vncShared": "Shared session",
     "vncUnencryptedWarning": "Classic VNC does not encrypt the desktop, keyboard, or clipboard traffic. Use a trusted network, VPN, or SSH tunnel.",
+    "vncUsernameHint": "Auto uses this username with RA2_256 servers. Classic VNC Authentication ignores it.",
+    "vncUsernamePlaceholder": "Username (for RA2_256)",
     "vncViewOnly": "View only",
     "workingDir": "Work Dir",
     "workingDirPlaceholder": "e.g. C:\\Projects or ~/workspace",
@@ -2713,6 +2715,12 @@
     "useOsKeyring": "Use OS Keyring",
     "useOsKeyringDesc": "Securely store credentials in the system's native keychain (macOS Keychain, Windows Credential Manager, Secret Service).",
     "viewPrivateKey": "View private key",
+    "vncServerKeyAccept": "Accept and remember",
+    "vncServerKeyBits": "RSA key",
+    "vncServerKeyVerifyChanged": "The saved VNC server key has changed. Verify the new key before reconnecting.",
+    "vncServerKeyVerifyNew": "The VNC server uses RA2_256 encryption. Verify this key before sending credentials.",
+    "vncServerKeyVerifyTitle": "VNC Server Key Verification",
+    "vncServerKeyVerifyWarning": "The VNC server key changed since the last trusted connection. Accept only if you expect this change.",
     "webdavEndpoint": "WebDAV Endpoint",
     "webdavEndpointRequired": "WebDAV endpoint is required.",
     "windowBehavior": "Window",

src/i18n/locales/ko.json

@@ -870,6 +870,8 @@
     "vncSecurityNone": "없음",
     "vncShared": "공유 세션",
     "vncUnencryptedWarning": "클래식 VNC는 데스크톱, 키보드 또는 클립보드 트래픽을 암호화하지 않습니다. 신뢰할 수 있는 네트워크, VPN 또는 SSH 터널을 사용하세요.",
+    "vncUsernameHint": "자동 모드는 RA2_256 서버에 이 사용자 이름을 사용합니다. 클래식 VNC 인증에서는 사용하지 않습니다.",
+    "vncUsernamePlaceholder": "사용자 이름(RA2_256용)",
     "vncViewOnly": "보기 전용",
     "workingDir": "작업 디렉터리",
     "workingDirPlaceholder": "예: C:\\Projects 또는 ~/workspace",
@@ -2711,6 +2713,12 @@
     "useOsKeyring": "OS 키체인 사용",
     "useOsKeyringDesc": "시스템 기본 키체인(macOS 키체인, Windows 자격 증명 관리자, Secret Service)에 자격 증명을 안전하게 저장합니다.",
     "viewPrivateKey": "개인 키 보기",
+    "vncServerKeyAccept": "수락하고 기억",
+    "vncServerKeyBits": "RSA 키",
+    "vncServerKeyVerifyChanged": "저장된 VNC 서버 키가 변경되었습니다. 다시 연결하기 전에 새 키를 확인하세요.",
+    "vncServerKeyVerifyNew": "VNC 서버가 RA2_256 암호화를 사용합니다. 자격 증명을 보내기 전에 이 키를 확인하세요.",
+    "vncServerKeyVerifyTitle": "VNC 서버 키 검증",
+    "vncServerKeyVerifyWarning": "VNC 서버 키가 마지막으로 신뢰한 연결과 다릅니다. 이 변경이 예상된 경우에만 수락하세요.",
     "webdavEndpoint": "WebDAV 엔드포인트",
     "webdavEndpointRequired": "WebDAV 엔드포인트가 필요합니다.",
     "windowBehavior": "창",

src/i18n/locales/zh-CN.json

@@ -870,6 +870,8 @@
     "vncSecurityNone": "无",
     "vncShared": "共享会话",
     "vncUnencryptedWarning": "经典 VNC 不会加密桌面、键盘或剪贴板流量。请使用可信网络、VPN 或 SSH 隧道。",
+    "vncUsernameHint": "自动模式会在 RA2_256 服务器上使用此用户名；经典 VNC 身份验证会忽略它。",
+    "vncUsernamePlaceholder": "用户名（用于 RA2_256）",
     "vncViewOnly": "仅查看",
     "workingDir": "工作目录",
     "workingDirPlaceholder": "例如：C:\\Projects 或 ~/workspace",
@@ -2711,6 +2713,12 @@
     "useOsKeyring": "使用系统凭据管理器（OS Keyring）",
     "useOsKeyringDesc": "将凭据安全地存储在系统原生钥匙串中 (macOS Keychain, Windows Credential Manager, Secret Service)。",
     "viewPrivateKey": "查看私钥",
+    "vncServerKeyAccept": "接受并记住",
+    "vncServerKeyBits": "RSA 密钥",
+    "vncServerKeyVerifyChanged": "已保存的 VNC 服务器密钥已更改。重新连接前请核对新密钥。",
+    "vncServerKeyVerifyNew": "VNC 服务器正在使用 RA2_256 加密。发送凭据前请核对此密钥。",
+    "vncServerKeyVerifyTitle": "VNC 服务器密钥验证",
+    "vncServerKeyVerifyWarning": "VNC 服务器密钥与上次信任的连接不同。仅在确认此次更改符合预期时接受。",
     "webdavEndpoint": "WebDAV 地址",
     "webdavEndpointRequired": "必须填写 WebDAV 地址。",
     "windowBehavior": "窗口行为",

src/i18n/locales/zh-TW.json

@@ -870,6 +870,8 @@
     "vncSecurityNone": "無",
     "vncShared": "共享工作階段",
     "vncUnencryptedWarning": "傳統 VNC 不會加密桌面、鍵盤或剪貼簿流量。請使用可信任網路、VPN 或 SSH 通道。",
+    "vncUsernameHint": "自動模式會在 RA2_256 伺服器上使用此使用者名稱；傳統 VNC 驗證會忽略它。",
+    "vncUsernamePlaceholder": "使用者名稱（用於 RA2_256）",
     "vncViewOnly": "僅檢視",
     "workingDir": "工作目錄",
     "workingDirPlaceholder": "例如：C:\\Projects 或 ~/workspace",
@@ -2706,6 +2708,12 @@
     "useOsKeyring": "使用系統認證管理器（OS Keyring）",
     "useOsKeyringDesc": "將認證資訊安全地儲存在系統原生鑰匙串中 (macOS Keychain, Windows Credential Manager, Secret Service)。",
     "viewPrivateKey": "檢視私鑰",
+    "vncServerKeyAccept": "接受並記住",
+    "vncServerKeyBits": "RSA 金鑰",
+    "vncServerKeyVerifyChanged": "已儲存的 VNC 伺服器金鑰已變更。重新連線前請核對新金鑰。",
+    "vncServerKeyVerifyNew": "VNC 伺服器正在使用 RA2_256 加密。傳送憑證前請核對此金鑰。",
+    "vncServerKeyVerifyTitle": "VNC 伺服器金鑰驗證",
+    "vncServerKeyVerifyWarning": "VNC 伺服器金鑰與上次信任的連線不同。僅在確認此次變更符合預期時接受。",
     "webdavEndpoint": "WebDAV 位址",
     "webdavEndpointRequired": "必須填寫 WebDAV 位址。",
     "windowBehavior": "視窗行為",

src/pages/NewSessionPage.test.tsx

@@ -9,6 +9,7 @@ const {
   invokeMock,
   localTerminalMock,
   rdpFormMock,
+  vncFormMock,
   serialFormMock,
   sshFormMock,
   telnetFormMock,
@@ -19,6 +20,7 @@ const {
   invokeMock: vi.fn(),
   localTerminalMock: vi.fn(),
   rdpFormMock: vi.fn(),
+  vncFormMock: vi.fn(),
   serialFormMock: vi.fn(),
   sshFormMock: vi.fn(),
   telnetFormMock: vi.fn(),
@@ -127,7 +129,12 @@ vi.mock("@/components/sessions/TelnetForm", () => ({
     );
   },
 }));
-vi.mock("@/components/sessions/VncForm", () => ({ VncForm: () => null }));
+vi.mock("@/components/sessions/VncForm", () => ({
+  VncForm: (props: Record<string, unknown>) => {
+    vncFormMock(props);
+    return null;
+  },
+}));
 vi.mock("@/components/sessions/RdpForm", () => ({
   RdpForm: (props: Record<string, unknown>) => {
     rdpFormMock(props);
@@ -230,6 +237,22 @@ const serialConnection: SavedConnection = {
   modem_upload_protocol: "ymodem",
 };
 
+const vncConnection: SavedConnection = {
+  id: "vnc-1",
+  name: "Raspberry Pi",
+  type: "vnc",
+  host: "pi.local",
+  port: 5900,
+  username: "pi",
+  auth: { mode: "password", has_password: true },
+  security: { mode: "auto" },
+  display: { scale_mode: "fit" },
+  clipboard: { enabled: true },
+  reconnect: { enabled: true, max_attempts: 5 },
+  shared: true,
+  view_only: false,
+};
+
 describe("NewSessionPage", () => {
   beforeEach(() => {
     window.history.replaceState({}, "", `/?edit=${rdpConnection.id}`);
@@ -269,6 +292,7 @@ describe("NewSessionPage", () => {
     });
     localTerminalMock.mockReset();
     rdpFormMock.mockReset();
+    vncFormMock.mockReset();
     serialFormMock.mockReset();
     sshFormMock.mockReset();
     telnetFormMock.mockReset();
@@ -568,4 +592,27 @@ describe("NewSessionPage", () => {
     expect(invokeMock).not.toHaveBeenCalledWith("save_connection", expect.anything());
     expect(closeMock).not.toHaveBeenCalled();
   });
+  it("restores and saves the optional VNC username", async () => {
+    window.history.replaceState({}, "", `/?edit=${vncConnection.id}`);
+    render(<NewSessionPage />);
+
+    await waitFor(() => {
+      expect(vncFormMock).toHaveBeenLastCalledWith(
+        expect.objectContaining({ username: "pi", securityMode: "auto" }),
+      );
+    });
+
+    fireEvent.click(screen.getByRole("button", { name: "dialog.save" }));
+    await waitFor(() => {
+      expect(invokeMock).toHaveBeenCalledWith(
+        "save_connection",
+        expect.objectContaining({
+          connection: expect.objectContaining({
+            type: "vnc",
+            username: "pi",
+          }),
+        }),
+      );
+    });
+  });
 });

src/pages/NewSessionPage.tsx

@@ -196,6 +196,7 @@ export default function NewSessionPage() {
   const [rdpPort, setRdpPort] = useState(3389);
   const [vncPort, setVncPort] = useState(5900);
   const [username, setUsername] = useState("root");
+  const [vncUsername, setVncUsername] = useState("");
   const [rdpDomain, setRdpDomain] = useState("");
   const [authType, setAuthType] = useState<SshAuthMode>("password");
   const [accountId, setAccountId] = useState("");
@@ -436,6 +437,7 @@ export default function NewSessionPage() {
         } else if (found.type === "vnc") {
           setHost(found.host || "");
           setVncPort(found.port || 5900);
+          setVncUsername(found.username || "");
           setPasswordId(found.auth?.password_id || "");
           setHasPassword(found.auth?.has_password || false);
           setVncSecurityMode(found.security?.mode ?? "auto");
@@ -493,6 +495,7 @@ export default function NewSessionPage() {
     setRdpPort(3389);
     setVncPort(5900);
     setUsername(currentTab === "rdp" ? DEFAULT_RDP_USERNAME : "root");
+    setVncUsername("");
     setRdpDomain("");
     setAuthType("password");
     setAccountId("");
@@ -1188,6 +1191,7 @@ export default function NewSessionPage() {
           ? {
               host: normalizedHost,
               port: vncPort,
+              username: vncUsername,
               auth,
               network,
               security: { mode: vncSecurityMode },
@@ -1818,6 +1822,8 @@ export default function NewSessionPage() {
               setHost={setHost}
               port={vncPort}
               setPort={setVncPort}
+              username={vncUsername}
+              setUsername={setVncUsername}
               passwordId={passwordId}
               setPasswordId={setPasswordId}
               password={password}