05/16 Enhanced codes

app/routes/vault.py

@@ -14,7 +14,7 @@ VALID_TYPES = {t.value for t in ItemType}
 @require_jwt
 def list_items():
     items = VaultItem.query.filter_by(user_id=g.current_user_id).order_by(
-        VaultItem.name.asc()
+        VaultItem.created_at.desc()
     ).all()
     return jsonify([item.to_dict() for item in items]), 200
 
@@ -164,7 +164,7 @@ def export_items():
                    created_at, updated_at }
     """
     items = VaultItem.query.filter_by(user_id=g.current_user_id).order_by(
-        VaultItem.name.asc()
+        VaultItem.created_at.desc()
     ).all()
     AuditLog.log(
         user_id=g.current_user_id,

app/services/auth_service.py

@@ -177,42 +177,11 @@ def generate_recovery_nonce() -> str:
     return os.urandom(32).hex()
 
 
-def compute_recovery_proof(recovery_enc_salt_b64: str, recovery_iv_b64: str, nonce: str) -> str:
-    """
-    Derive the expected HMAC-SHA256 proof tag that the client must produce.
-
-    The client-side proof is:
-        key_material  = AES-GCM-decrypt(recovery_key, recovery_enc_salt_ciphertext)
-                      = enc_key_salt (plaintext bytes)
-        proof         = HMAC-SHA256(key=enc_key_salt_bytes, msg=nonce_bytes)
-
-    The server replicates this using the stored ciphertext + its TOTP encryption
-    key is NOT involved here — the recovery blob was encrypted with the *client*
-    recovery key.  The server cannot decrypt it, so instead the server stores the
-    expected HMAC in flask.session alongside the nonce at challenge time and
-    compares on submission.
-
-    Because the server cannot decrypt the recovery blob, the proof is stored in
-    session at challenge issue time as a constant-time secret:
-        session['recovery_expected_proof'] = HMAC-SHA256(server_secret, nonce)
-    That binding is verified on submission without ever seeing enc_key_salt.
-
-    Concretely:
-        expected_tag = HMAC-SHA256(key=SECRET_KEY_bytes, msg=nonce_hex_bytes)
-
-    The client sends:
-        client_tag   = HMAC-SHA256(key=enc_key_salt_bytes, msg=nonce_hex_bytes)
-
-    These are different keys — so the server never validates client_tag directly.
-    Instead, the server trusts GCM authentication: if the client can decrypt
-    recovery_enc_salt (GCM will throw on wrong key), the decrypted value IS
-    enc_key_salt. The server then computes:
-        expected = HMAC-SHA256(key=user.enc_key_salt.encode(), msg=nonce.encode())
-    and compares it to client_tag in constant time.
-    """
-    key = base64.b64decode(recovery_enc_salt_b64)  # unused — see docstring
-    msg = nonce.encode()
-    return hmac.new(key, msg, hashlib.sha256).hexdigest()
+# NOTE: compute_recovery_proof() is intentionally absent.
+# The server cannot decrypt the recovery blob (it was encrypted client-side with
+# the user's recovery key). Instead, the expected HMAC is computed inline in
+# the /recovery/data route using user.enc_key_salt as the HMAC key, stored in
+# flask.session, and compared on submission via verify_recovery_proof() below.
 
 
 def verify_recovery_proof(expected_hmac: str, client_hmac: str) -> bool:
@@ -235,20 +204,12 @@ def generate_backup_codes() -> tuple[list[str], list[str]]:
     The plaintext list is shown to the user ONCE and never stored.
     Only the hashed list is persisted in user.mfa_backup_codes (JSON array).
     """
+    import secrets
     ph = PasswordHasher(
         time_cost=1,          # backup codes can afford lighter params than master password
         memory_cost=16384,
         parallelism=2,
     )
-    plaintext = [
-        ''.join(os.urandom(1)[0] % len(_BACKUP_ALPHABET)
-                and _BACKUP_ALPHABET[os.urandom(1)[0] % len(_BACKUP_ALPHABET)]
-                or _BACKUP_ALPHABET[os.urandom(1)[0] % len(_BACKUP_ALPHABET)]
-                for _ in range(BACKUP_CODE_LENGTH))
-        for _ in range(BACKUP_CODE_COUNT)
-    ]
-    # Simpler generation using secrets module for clarity and correctness:
-    import secrets
     plaintext = [
         ''.join(secrets.choice(_BACKUP_ALPHABET) for _ in range(BACKUP_CODE_LENGTH))
         for _ in range(BACKUP_CODE_COUNT)