X-Git-Url: http://www.git.cypherpunks.ru/?a=blobdiff_plain;f=pygost%2Fgost3410.py;h=58a20e0fe7c6a06020dc90c34e80c76ca78b0150;hb=9ab3b1d03f734f4aae28364f7a6c7c7c223b30a9;hp=a2cc7cef015507d4db84955cd4a9b9ea392adf29;hpb=f3a3246bc9da027e0527b89204e1b95ed52af5c6;p=pygost.git

diff --git a/pygost/gost3410.py b/pygost/gost3410.py
index a2cc7ce..58a20e0 100644
--- a/pygost/gost3410.py
+++ b/pygost/gost3410.py
@@ -1,6 +1,6 @@
 # coding: utf-8
 # PyGOST -- Pure Python GOST cryptographic functions library
-# Copyright (C) 2015-2020 Sergey Matveev <stargrave@stargrave.org>
+# Copyright (C) 2015-2021 Sergey Matveev <stargrave@stargrave.org>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -120,7 +120,7 @@ class GOST3410Curve(object):
         """Compute s/t parameters for twisted Edwards curve points conversion
         """
         if self.e is None or self.d is None:
-            raise ValueError("non twisted Edwards curve")
+            raise ValueError("Non twisted Edwards curve")
         if self._st is not None:
             return self._st
         self._st = (
@@ -324,10 +324,26 @@ def prv_unmarshal(prv):
 
     :param bytes prv: serialized private key
     :rtype: long
+
+    It is advisable to use :py:func:`pygost.gost3410.prv_marshal` to
+    assure that key i in curve's Q field for better compatibility with
+    some implementations.
     """
     return bytes2long(prv[::-1])
 
 
+def prv_marshal(curve, prv):
+    """Marshal little-endian private key
+
+    :param GOST3410Curve curve: curve to use
+    :param long prv: serialized private key
+    :rtype: bytes
+
+    Key is in curve's Q field.
+    """
+    return long2bytes(prv % curve.q, point_size(prv))[::-1]
+
+
 def pub_marshal(pub):
     """Marshal public key