From 6061d170c7993f943a7ee5443ed9ddc544459b9e Mon Sep 17 00:00:00 2001
From: Nikolay Morozov <nmorozoff77@yandex.ru>
Date: Wed, 12 Feb 2020 14:21:59 +0300
Subject: [PATCH] Destroy GOST key data with OPENSSL_cleanse()

---
 CMakeLists.txt |  2 +-
 gost89.c       | 12 ++++++++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8036d34..4c06970 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -245,7 +245,7 @@ set(GOST_SUM_SOURCE_FILES
         )
 
 add_executable(gostsum ${GOST_SUM_SOURCE_FILES})
-target_link_libraries(gostsum gost_core)
+target_link_libraries(gostsum gost_core ${OPENSSL_CRYPTO_LIBRARY})
 
 set(GOST_12_SUM_SOURCE_FILES
         gost12sum.c
diff --git a/gost89.c b/gost89.c
index 593bc23..e84ec91 100644
--- a/gost89.c
+++ b/gost89.c
@@ -8,6 +8,7 @@
  *                              this code                             *
  **********************************************************************/
 #include <string.h>
+#include <openssl/crypto.h>
 #include "gost89.h"
 /*-
    Substitution blocks from RFC 4357
@@ -503,9 +504,7 @@ void gost_init(gost_ctx * c, const gost_subst_block * b)
 /* Cleans up key from context */
 void gost_destroy(gost_ctx * c)
 {
-    int i;
-    for (i = 0; i < 8; i++)
-        c->k[i] = 0;
+    OPENSSL_cleanse(c->k, sizeof(c->k));
 }
 
 /*
@@ -627,11 +626,13 @@ void cryptopro_key_meshing(gost_ctx * ctx, unsigned char *iv)
     gost_dec(ctx, CryptoProKeyMeshingKey, newkey, 4);
     /* set new key */
     gost_key(ctx, newkey);
+    OPENSSL_cleanse(newkey, sizeof(newkey));
     /* Encrypt iv with new key */
     if (iv != NULL ) {
         unsigned char newiv[8];
         gostcrypt(ctx, iv, newiv);
         memcpy(iv, newiv, 8);
+        OPENSSL_cleanse(newiv, sizeof(newiv));
     }
 }
 
@@ -639,16 +640,19 @@ void acpkm_magma_key_meshing(gost_ctx * ctx)
 {
     unsigned char newkey[32];
     int i, j;
-    unsigned char buf[8], keybuf[8];
 
     for (i = 0; i < 4; i++) {
+        unsigned char buf[8], keybuf[8];
         for (j = 0; j < 8; j++) {
             buf[j] = ACPKM_D_const[8 * i + 7 - j];
         }
         gostcrypt(ctx, buf, keybuf);
         memcpy(newkey + 8 * i, keybuf + 4, 4);
         memcpy(newkey + 8 * i + 4, keybuf, 4);
+        OPENSSL_cleanse(keybuf, sizeof(keybuf));
+        OPENSSL_cleanse(buf, sizeof(buf));
     }
     /* set new key */
     gost_key(ctx, newkey);
+    OPENSSL_cleanse(newkey, sizeof(newkey));
 }
-- 
2.39.2