From: Dmitry Belyavskiy <beldmit@gmail.com>
Date: Thu, 27 Dec 2018 23:34:46 +0000 (+0300)
Subject: Bugfix of seq decrement
X-Git-Tag: v3.0.0~319
X-Git-Url: http://www.wagner.pp.ru/gitweb/?a=commitdiff_plain;h=2b79bbba6aed4e69b1d2d0c04da00f121c69799d;p=openssl-gost%2Fengine.git

Bugfix of seq decrement
---

diff --git a/gost_grasshopper_cipher.c b/gost_grasshopper_cipher.c
index 050ec7a..b6d044f 100644
--- a/gost_grasshopper_cipher.c
+++ b/gost_grasshopper_cipher.c
@@ -785,7 +785,7 @@ int gost_grasshopper_cipher_ctl(EVP_CIPHER_CTX *ctx, int type, int arg,
               memcpy(seq, ptr, 8);
               if (EVP_CIPHER_CTX_encrypting(ctx)) {
               /*
-               * OpenSSL increments seq on after mac calculation
+               * OpenSSL increments seq after mac calculation.
                * As we have Mac-Then-Encrypt, we need decrement it here on encryption
                * to derive the key correctly.
                * */
@@ -793,7 +793,8 @@ int gost_grasshopper_cipher_ctl(EVP_CIPHER_CTX *ctx, int type, int arg,
                 {
                   for(j=7; j>=0; j--)
                   {
-                    if (seq[j] != 0) {seq[j]--; break;};
+                    if (seq[j] != 0) {seq[j]--; break;}
+                    else seq[j]  = 0xFF;
                   }
                 }
               }