X-Git-Url: http://www.git.cypherpunks.ru/?a=blobdiff_plain;f=pygost%2Fgost3413.py;h=27f0c30dc79a75de4e66f8e284455221474fa215;hb=a9f7e3dfc59a987c3d6cce4108f18d9f6b72867b;hp=32be5a33f33f6a628bf2aac239f15e160f6e1df7;hpb=31b08d5a78505f0ae1a144e58d023d84eda2cc6e;p=pygost.git

diff --git a/pygost/gost3413.py b/pygost/gost3413.py
index 32be5a3..27f0c30 100644
--- a/pygost/gost3413.py
+++ b/pygost/gost3413.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) 2015-2022 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
@@ -18,6 +18,8 @@
 This module currently includes only padding methods.
 """
 
+from os import urandom
+
 from pygost.utils import bytes2long
 from pygost.utils import long2bytes
 from pygost.utils import strxor
@@ -365,3 +367,26 @@ def mac_acpkm_master(algo_class, encrypter, key_section_size, section_size, bs,
         strxor(pad3(tail, bs), prev),
         k1 if len(tail) == bs else k2,
     ))
+
+
+def pad_iso10126(data, blocksize):
+    """ISO 10126 padding
+
+    Does not exist in 34.13, but added for convenience.
+    It uses urandom call for getting the randomness.
+    """
+    pad_len = blocksize - len(data) % blocksize
+    if pad_len == 0:
+        pad_len = blocksize
+    return b"".join((data, urandom(pad_len - 1), bytes((pad_len,))))
+
+
+def unpad_iso10126(data, blocksize):
+    """Unpad :py:func:`pygost.gost3413.pad_iso10126`
+    """
+    if len(data) % blocksize != 0:
+        raise ValueError("Data length is not multiple of blocksize")
+    pad_len = bytearray(data)[-1]
+    if pad_len > blocksize:
+        raise ValueError("Padding length is bigger than blocksize")
+    return data[:-pad_len]