diff --git a/mtproto.py b/mtproto.py
index 651a88bb..966f3bb5 100644
--- a/mtproto.py
+++ b/mtproto.py
@@ -139,11 +139,11 @@ def deserialize(bytes_io, type_=None, subtype=None):
     elif type_ == 'int128': x = bytes_io.read(16)
     elif type_ == 'int256': x = bytes_io.read(32)
     elif type_ == 'string' or type_ == 'bytes':
-        l = struct.unpack('<b', bytes_io.read(1))[0]
+        l = struct.unpack('<B', bytes_io.read(1))[0]
         assert l <= 254  # In general, 0xFF byte is not allowed here
         if l == 254:
             # We have a long string
-            long_len = struct.unpack('<i', bytes_io.read(3))[0]
+            long_len = struct.unpack('<I', bytes_io.read(3)+b'\x00')[0]
             x = bytes_io.read(long_len)
             bytes_io.read(-long_len % 4)  # skip padding bytes
         else:
diff --git a/testing.py b/testing.py
index fbf6ff4a..fbf46eb0 100644
--- a/testing.py
+++ b/testing.py
@@ -11,6 +11,7 @@ except ImportError:
     import ConfigParser as configparser
 from Crypto.Hash import SHA
 from Crypto.PublicKey import RSA
+from Crypto.Cipher import AES
 
 config = configparser.ConfigParser()
 # Check if credentials is correctly loaded (when it doesn't read anything it returns [])
@@ -73,5 +74,12 @@ z = Session.method_call('req_DH_params',
                         public_key_fingerprint=public_key_fingerprint,
                         encrypted_data=encrypted_data)
 
-print(z)
+encrypted_answer = z['encrypted_answer']
+tmp_aes_key = SHA.new(new_nonce + server_nonce).digest() + SHA.new(server_nonce + new_nonce).digest()[0:12]
+tmp_aes_iv = SHA.new(server_nonce + new_nonce).digest()[12:20] + SHA.new(new_nonce + new_nonce).digest() + new_nonce[0:4]
 
+print("\ntmp_aes_key:")
+mtproto.vis(tmp_aes_key)
+
+print("\ntmp_aes_iv:")
+mtproto.vis(tmp_aes_iv)