Refactors Cryptographer to remove logs and avoid multi return types

Cryptographer now uses exceptions to report errors and does not use the log anymore

teos/gatekeeper.py

@@ -1,5 +1,6 @@
 from common.tools import is_compressed_pk
 from common.cryptographer import Cryptographer
+from common.exceptions import InvalidParameter, InvalidKey, SignatureError
 
 
 class NotEnoughSlots(ValueError):
@@ -71,7 +72,7 @@ class Gatekeeper:
             :obj:`IdentificationFailure`: if the user cannot be identified.
         """
 
-        if isinstance(message, bytes) and isinstance(signature, str):
+        try:
             rpk = Cryptographer.recover_pk(message, signature)
             compressed_pk = Cryptographer.get_compressed_pk(rpk)
 
@@ -80,7 +81,7 @@ class Gatekeeper:
             else:
                 raise IdentificationFailure("User not found.")
 
-        else:
+        except (InvalidParameter, InvalidKey, SignatureError):
             raise IdentificationFailure("Wrong message or signature.")
 
     def fill_slots(self, user_pk, n):

teos/inspector.py

@@ -1,6 +1,5 @@
 import re
 
-import common.cryptographer
 from common.logger import Logger
 from common.tools import is_locator
 from common.constants import LOCATOR_LEN_HEX
@@ -9,7 +8,6 @@ from common.appointment import Appointment
 from teos import errors, LOG_PREFIX
 
 logger = Logger(actor="Inspector", log_name_prefix=LOG_PREFIX)
-common.cryptographer.logger = Logger(actor="Cryptographer", log_name_prefix=LOG_PREFIX)
 
 # FIXME: The inspector logs the wrong messages sent form the users. A possible attack surface would be to send a really
 #        long field that, even if not accepted by TEOS, would be stored in the logs. This is a possible DoS surface

teos/teosd.py

@@ -3,7 +3,6 @@ from sys import argv, exit
 from getopt import getopt, GetoptError
 from signal import signal, SIGINT, SIGQUIT, SIGTERM
 
-import common.cryptographer
 from common.logger import Logger
 from common.config_loader import ConfigLoader
 from common.cryptographer import Cryptographer
@@ -25,7 +24,6 @@ from teos.tools import can_connect_to_bitcoind, in_correct_network
 from teos import LOG_PREFIX, DATA_DIR, DEFAULT_CONF, CONF_FILE_NAME
 
 logger = Logger(actor="Daemon", log_name_prefix=LOG_PREFIX)
-common.cryptographer.logger = Logger(actor="Cryptographer", log_name_prefix=LOG_PREFIX)
 
 
 def handle_signals(signal_received, frame):

teos/watcher.py

@@ -1,17 +1,17 @@
 from queue import Queue
 from threading import Thread
 
-import common.cryptographer
 from common.logger import Logger
 from common.tools import compute_locator
 from common.appointment import Appointment
+from common.exceptions import EncryptionError
 from common.cryptographer import Cryptographer, hash_160
+from common.exceptions import InvalidParameter, SignatureError
 
 from teos import LOG_PREFIX
 from teos.cleaner import Cleaner
 
 logger = Logger(actor="Watcher", log_name_prefix=LOG_PREFIX)
-common.cryptographer.logger = Logger(actor="Cryptographer", log_name_prefix=LOG_PREFIX)
 
 
 class Watcher:
@@ -57,7 +57,7 @@ class Watcher:
         last_known_block (:obj:`str`): the last block known by the ``Watcher``.
 
     Raises:
-        ValueError: if `teos_sk_file` is not found.
+        :obj:`InvalidKey <common.exceptions.InvalidKey>`: if teos sk cannot be loaded.
 
     """
 
@@ -147,7 +147,14 @@ class Watcher:
             self.db_manager.create_append_locator_map(appointment.locator, uuid)
 
             appointment_added = True
-            signature = Cryptographer.sign(appointment.serialize(), self.signing_key)
+
+            try:
+                signature = Cryptographer.sign(appointment.serialize(), self.signing_key)
+
+            except (InvalidParameter, SignatureError):
+                # This should never happen since data is sanitized, just in case to avoid a crash
+                logger.error("Data couldn't be signed", appointment=appointment.to_dict())
+                signature = None
 
             logger.info("New appointment accepted", locator=appointment.locator)
 
@@ -297,7 +304,7 @@ class Watcher:
                     try:
                         penalty_rawtx = Cryptographer.decrypt(appointment.encrypted_blob, dispute_txid)
 
-                    except ValueError:
+                    except EncryptionError:
                         penalty_rawtx = None
 
                     penalty_tx = self.block_processor.decode_raw_transaction(penalty_rawtx)