diff --git a/src/password_manager/encryption.py b/src/password_manager/encryption.py
index 40f3b31..db42c6b 100644
--- a/src/password_manager/encryption.py
+++ b/src/password_manager/encryption.py
@@ -339,11 +339,13 @@ class EncryptionManager:
             relative_path = Path("seedpass_passwords_db.json.enc")
         try:
             file_path = self.fingerprint_dir / relative_path
-            decrypted_data = self.decrypt_file(relative_path)
-            content = decrypted_data.decode("utf-8")
-            logger.debug("Calculating checksum of the updated file content.")
+            logger.debug("Calculating checksum of the encrypted file bytes.")
 
-            checksum = hashlib.sha256(content.encode("utf-8")).hexdigest()
+            with exclusive_lock(file_path):
+                with open(file_path, "rb") as f:
+                    encrypted_bytes = f.read()
+
+            checksum = hashlib.sha256(encrypted_bytes).hexdigest()
             logger.debug(f"New checksum: {checksum}")
 
             checksum_file = file_path.parent / f"{file_path.stem}_checksum.txt"
diff --git a/src/tests/test_encryption_checksum.py b/src/tests/test_encryption_checksum.py
new file mode 100644
index 0000000..0922e8d
--- /dev/null
+++ b/src/tests/test_encryption_checksum.py
@@ -0,0 +1,34 @@
+import re
+import sys
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+from cryptography.fernet import Fernet
+
+sys.path.append(str(Path(__file__).resolve().parents[1]))
+
+from password_manager.encryption import EncryptionManager
+from utils.checksum import verify_and_update_checksum
+
+
+def test_encryption_checksum_workflow():
+    with TemporaryDirectory() as tmpdir:
+        tmp_path = Path(tmpdir)
+        key = Fernet.generate_key()
+        manager = EncryptionManager(key, tmp_path)
+
+        data = {"value": 1}
+        manager.save_json_data(data)
+        manager.update_checksum()
+
+        enc_file = tmp_path / "seedpass_passwords_db.json.enc"
+        chk_file = tmp_path / "seedpass_passwords_db.json_checksum.txt"
+
+        checksum = chk_file.read_text().strip()
+        assert re.fullmatch(r"[0-9a-f]{64}", checksum)
+
+        manager.save_json_data({"value": 2})
+        assert not verify_and_update_checksum(str(enc_file), str(chk_file))
+
+        manager.update_checksum()
+        assert verify_and_update_checksum(str(enc_file), str(chk_file))