Avoid using BinaryWriter where possible

telethon/crypto/auth_key.py

@@ -1,7 +1,8 @@
+import struct
 from hashlib import sha1
 
 from .. import helpers as utils
-from ..extensions import BinaryReader, BinaryWriter
+from ..extensions import BinaryReader
 
 
 class AuthKey:
@@ -17,10 +18,5 @@ class AuthKey:
         """Calculates the new nonce hash based on
            the current class fields' values
         """
-        with BinaryWriter() as writer:
-            writer.write(new_nonce)
-            writer.write_byte(number)
-            writer.write_long(self.aux_hash, signed=False)
-
-            new_nonce_hash = utils.calc_msg_key(writer.get_bytes())
-            return new_nonce_hash
+        data = new_nonce + struct.pack('<BQ', number, self.aux_hash)
+        return utils.calc_msg_key(data)

telethon/crypto/rsa.py

@@ -7,7 +7,7 @@ except ImportError:
     rsa = None
     raise ImportError('Missing module "rsa", please install via pip.')
 
-from ..extensions import BinaryWriter
+from ..tl import TLObject
 
 
 # {fingerprint: Crypto.PublicKey.RSA._RSAobj} dictionary
@@ -34,11 +34,10 @@ def _compute_fingerprint(key):
     """For a given Crypto.RSA key, computes its 8-bytes-long fingerprint
        in the same way that Telegram does.
     """
-    with BinaryWriter() as writer:
-        writer.tgwrite_bytes(get_byte_array(key.n))
-        writer.tgwrite_bytes(get_byte_array(key.e))
-        # Telegram uses the last 8 bytes as the fingerprint
-        return sha1(writer.get_bytes()).digest()[-8:]
+    n = TLObject.serialize_bytes(get_byte_array(key.n))
+    e = TLObject.serialize_bytes(get_byte_array(key.e))
+    # Telegram uses the last 8 bytes as the fingerprint
+    return sha1(n + e).digest()[-8:]
 
 
 def add_key(pub):