diff --git a/.gitignore b/.gitignore
index b836702..af6d8c8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,5 +5,7 @@ __pycache__
 Pipfile.lock
 /*bin
 *log
-*pyc
-.tox
\ No newline at end of file
+*.pyc
+.vscode
+.idea/
+.tox
diff --git a/exonum/transactions.py b/exonum/transactions.py
index 4f73bea..18c6ee3 100644
--- a/exonum/transactions.py
+++ b/exonum/transactions.py
@@ -5,7 +5,7 @@
 from itertools import chain
 
 from pysodium import crypto_sign_BYTES as SIGNATURE_SZ
-from pysodium import crypto_sign_detached
+from pysodium import crypto_sign_detached, crypto_hash_sha256
 
 from .datatypes import EncodingStruct, ExonumBase, TxHeader
 from .error import IllegalServiceId, NotEncodingStruct
@@ -24,7 +24,7 @@ def tx(self, secret_key, hex=False):
             header_fmt,
             buf,
             0,
-            kwargs["network_id"],
+            0,  # network_id field doesn't use anymore but place is reserved with value 0
             kwargs["protocol_version"],
             kwargs["message_id"],
             kwargs["service_id"],
@@ -43,13 +43,12 @@ def tx(self, secret_key, hex=False):
 
 
 class transactions(object):
-    def __init__(self, service_id=-1, protocol_version=0, network_id=0):
+    def __init__(self, service_id=-1, protocol_version=0):
         if service_id < 0:
             raise IllegalServiceId()
 
         self.service_id = service_id
         self.protocol_version = protocol_version
-        self.network_id = network_id
         self.tx = []
 
     @staticmethod
@@ -69,7 +68,11 @@ def __call__(self, cls):
         class Tx(tx_cls):
             def __init__(tx_self, *args, **kwargs):
                 if "message_id" not in kwargs:
-                    kwargs["network_id"] = self.network_id
+                    kwargs[
+                        "network_id"
+                    ] = (
+                        0
+                    )  # network_id field doesn't use anymore but place is reserved with value 0
                     kwargs["protocol_version"] = self.protocol_version
                     kwargs["message_id"] = message_id
                     kwargs["service_id"] = self.service_id
@@ -96,7 +99,15 @@ def tx(self, secret_key, hex=False):
                     k: v for k, v in plain.items() if k not in meta_fields
                 }
                 del message["payload_sz"]
+                del message[
+                    "network_id"
+                ]  # network_id field doesn't use anymore in JSON
                 return message
 
+            def hash(self, secret_key):
+                tx_bytes = self.tx(secret_key, hex=True)
+                tx_hash = crypto_hash_sha256(tx_bytes)
+                return codecs.encode(tx_hash, "hex").decode("utf-8")
+
         self.tx.append(cls.__name__)
         return Tx
diff --git a/tests/test_serde.py b/tests/test_serde.py
index c8ff4a4..67b4baa 100644
--- a/tests/test_serde.py
+++ b/tests/test_serde.py
@@ -1,8 +1,6 @@
 # coding: utf-8
 from uuid import uuid4
-
 from six import with_metaclass
-
 from exonum.datatypes import (
     Decimal,
     EncodingStruct,
@@ -76,14 +74,14 @@ class X(with_metaclass(EncodingStruct)):
     assert raw == z
 
 
-# def test_segment_vector():
-#     class X(with_metaclass(EncodingStruct)):
-#         f = Vec(Str)
+def test_segment_vector():
+    class X(with_metaclass(EncodingStruct)):
+        f = Vec(Str)
 
-#     x = X(f=[u"am", u"i", u"working", u"or", u"what?"])
-#     raw = x.to_bytes()
-#     xx = X.read_buffer(raw)
-#     assert xx.f.val == x.f.val
+    x = X(f=[u"am", u"i", u"working", u"or", u"what?"])
+    raw = x.to_bytes()
+    xx = X.read_buffer(raw)
+    assert xx.f.val == x.f.val
 
 
 def test_inner():
diff --git a/tests/test_tx.py b/tests/test_tx.py
index e13de65..612f267 100644
--- a/tests/test_tx.py
+++ b/tests/test_tx.py
@@ -11,6 +11,7 @@
 
 transactions = tx.transactions(service_id=250)
 
+
 # py3
 # class Policy(metaclass=exonum.EncodingStruct):
 #    ...
diff --git a/work.py b/work.py
index 9f08f24..5026fbf 100644
--- a/work.py
+++ b/work.py
@@ -1,8 +1,8 @@
-from uuid import uuid4
-
+import json
 import exonum.transactions as tx
 import exonum.datatypes as exonum
 
+from uuid import uuid4
 from pysodium import crypto_sign_keypair
 
 from importlib import reload
@@ -33,12 +33,11 @@
 
 @transactions
 class CreateUser(metaclass=exonum.EncodingStruct):
-    public_key = exonum.PublicKey
-    name = exonum.Str
+    public_key = exonum.PublicKey()
+    name = exonum.Str()
 
 
 a = CreateUser(public_key=public_key, name="Me")
 
-import json
-
 print(json.dumps(a.tx(secret_key), indent=2))
+print("tx hash:", a.hash(secret_key))