diff --git a/markbase-core/src/ssh_server/cipher.rs b/markbase-core/src/ssh_server/cipher.rs
index af5d632..e9dd2fb 100644
--- a/markbase-core/src/ssh_server/cipher.rs
+++ b/markbase-core/src/ssh_server/cipher.rs
@@ -513,9 +513,13 @@ impl EncryptedPacket {
             info!("  sequence_number: {}", sequence_number);
             info!("  mac_key length: {}", mac_key.len());
             info!("  plaintext_packet length: {}", plaintext_packet.len());
+            info!("  plaintext_packet first 8 bytes: {:?}", &plaintext_packet.ptr()[..std::cmp::min(8, plaintext_packet.len())]);
+            info!("  mac_key first 8 bytes: {:?}", &mac_key[..std::cmp::min(8, mac_key.len())]);
 
             // MAC計算：HMAC(sequence_number || plaintext_packet)
             let mac = encryption_ctx.compute_mac(sequence_number, plaintext_packet.ptr(), mac_key)?;
+            
+            info!("  Calculated MAC first 8 bytes: {:?}", &mac[..std::cmp::min(8, mac.len())]);
 
             // 然後加密plaintext packet（AES-CTR加密整個packet）
             let cipher = if is_server_to_client {