Phase 1.3: SMB3 packet encryption handling complete

- Add handle_encrypted_frame() to dispatch.rs
- Detect TRANSFORM_HEADER magic (0x534D4220)
- Decrypt incoming packets using session.encryption_key
- Encrypt outgoing responses
- All encryption tests pass (3 passed)

Phase 1 SMB3 encryption complete: ~380 lines total

vendor/smb-server/src/dispatch.rs

@@ -4,6 +4,7 @@ use std::sync::Arc;
 
 use crate::proto::auth::ntlm::Identity;
 use crate::proto::crypto::{PreauthIntegrity, sign};
+use crate::proto::crypto::encryption::{Smb3Encryption, CipherAlgorithm, TransformHeader};
 use crate::proto::header::{
     Command, HeaderTail, SMB2_FLAGS_ASYNC_COMMAND, SMB2_FLAGS_RELATED_OPERATIONS,
     SMB2_FLAGS_SERVER_TO_REDIR, SMB2_FLAGS_SIGNED, SMB2_HEADER_LEN, Smb2Header,
@@ -82,6 +83,16 @@ pub async fn dispatch_frame(
     if let Some(bytes) = handle_smb1_multi_protocol(server, conn, frame).await {
         return Some(bytes);
     }
+    
+    // SMB3 encryption check: TRANSFORM_HEADER magic (0x534D4220 = "SMB ")
+    if frame.len() >= 4 {
+        let magic = u32::from_be_bytes([frame[0], frame[1], frame[2], frame[3]]);
+        if magic == 0x534D4220 {
+            // Encrypted packet - decrypt and process
+            return handle_encrypted_frame(server, conn, frame).await;
+        }
+    }
+    
     if frame.len() < SMB2_HEADER_LEN {
         warn!(len = frame.len(), "frame too short for SMB2 header");
         return None;
@@ -156,6 +167,94 @@ pub async fn dispatch_frame(
     Some(stitch_responses(conn, responses).await)
 }
 
+/// Handle SMB3 encrypted frame (TRANSFORM_HEADER)
+async fn handle_encrypted_frame(
+    server: &Arc<ServerState>,
+    conn: &Arc<Connection>,
+    encrypted_frame: &[u8],
+) -> Option<Vec<u8>> {
+    // Parse TRANSFORM_HEADER
+    let header = match TransformHeader::read_from_bytes(encrypted_frame) {
+        Ok(h) => h,
+        Err(e) => {
+            warn!(error = %e, "failed to parse TRANSFORM_HEADER");
+            return None;
+        }
+    };
+    
+    // Get session encryption key
+    let sessions = conn.sessions.read().await;
+    let session_arc = match sessions.get(&header.session_id).cloned() {
+        Some(s) => s,
+        None => {
+            warn!(session_id = header.session_id, "session not found for encrypted packet");
+            return None;
+        }
+    };
+    
+    let session = session_arc.read().await;
+    let encryption_enabled = session.encryption_enabled;
+    let encryption_key = session.encryption_key;
+    
+    if !encryption_enabled {
+        warn!("session does not have encryption enabled");
+        return None;
+    }
+    
+    let encryption_key = match encryption_key {
+        Some(k) => k,
+        None => {
+            warn!("session has no encryption key");
+            return None;
+        }
+    };
+    
+    // Decrypt packet
+    let encryption = match Smb3Encryption::new(&encryption_key, CipherAlgorithm::Aes128Gcm) {
+        Ok(e) => e,
+        Err(e) => {
+            warn!(error = %e, "failed to create encryption context");
+            return None;
+        }
+    };
+    
+    let decrypted = match encryption.decrypt_packet(encrypted_frame) {
+        Ok(d) => d,
+        Err(e) => {
+            warn!(error = %e, "failed to decrypt packet");
+            return None;
+        }
+    };
+    
+    debug!(session_id = header.session_id, "decrypted SMB3 packet");
+    
+    // Process decrypted frame (non-recursive: call dispatch_one directly)
+    if decrypted.len() < SMB2_HEADER_LEN {
+        warn!("decrypted frame too short");
+        return None;
+    }
+    
+    let response = dispatch_one(server, conn, &decrypted).await;
+    
+    // Encrypt response if needed
+    if let Some(resp_bytes) = response {
+        if encryption_enabled {
+            let encrypted_response = match encryption.encrypt_packet(&resp_bytes, header.session_id) {
+                Ok(e) => e,
+                Err(e) => {
+                    warn!(error = %e, "failed to encrypt response");
+                    return Some(resp_bytes);
+                }
+            };
+            debug!("encrypted response packet");
+            return Some(encrypted_response);
+        }
+        return Some(resp_bytes);
+    }
+    
+    None
+}
+
 fn inherit_related_context(
     sub_frame: &mut [u8],
     req_hdr: &mut Smb2Header,