From d7cf18d77f96e9a69cde610523e7a84efc8bc76a Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Tue, 31 May 2022 16:16:04 +0300
Subject: [PATCH] Simpler and slightly faster 512-bit-addition code

---
 pygost/gost34112012.py | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/pygost/gost34112012.py b/pygost/gost34112012.py
index f1a7acc..48d7ae2 100644
--- a/pygost/gost34112012.py
+++ b/pygost/gost34112012.py
@@ -184,16 +184,10 @@ LCache = _lcache()
 
 
 def add512bit(a, b):
-    """Add two 512 integers
-    """
-    a = bytearray(a)
-    b = bytearray(b)
-    cb = 0
-    res = bytearray(64)
-    for i in range(64):
-        cb = a[i] + b[i] + (cb >> 8)
-        res[i] = cb & 0xff
-    return res
+    a = int.from_bytes(a, "little")
+    b = int.from_bytes(b, "little")
+    r = (a + b) % (1 << 512)
+    return r.to_bytes(512 // 8, "little")
 
 
 def g(n, hsh, msg):
-- 
2.44.0