diff --git a/backend/coffre_crypto.py b/backend/coffre_crypto.py
index 438773b..ff92dde 100644
--- a/backend/coffre_crypto.py
+++ b/backend/coffre_crypto.py
@@ -177,7 +177,7 @@ def unwrap_dek(wrapped: dict, kek: bytes, coffre_id: str) -> bytes:
 
 def encrypt_secret_value(dek: bytes, secret_id: str, version: int, valeur: str) -> dict:
     """Chiffre une valeur de secret (AAD = secret_id:version)."""
-    aad = f"{secret_id}:{version}".encode("utf-8")
+    aad = f"{secret_id}:{version}".encode()
     return encrypt_with_key(dek, valeur.encode("utf-8"), aad)
 
 
@@ -185,7 +185,7 @@ def decrypt_secret_value(
     dek: bytes, secret_id: str, version: int, nonce_b64: str, ciphertext_b64: str
 ) -> str:
     """Déchiffre une valeur de secret."""
-    aad = f"{secret_id}:{version}".encode("utf-8")
+    aad = f"{secret_id}:{version}".encode()
     return decrypt_with_key(dek, nonce_b64, ciphertext_b64, aad).decode("utf-8")