From 0f8a6477825fbaad0d37233bdd3011d748f607ab Mon Sep 17 00:00:00 2001
From: Philip Kaufmann <phil.kaufmann@t-online.de>
Date: Thu, 8 Nov 2012 19:38:49 +0100
Subject: [PATCH 1/2] don't use memset() in privacy/security relevant code
 parts

As memset() can be optimized out by a compiler it should not be used in
privacy/security relevant code parts. OpenSSL provides the safe
OPENSSL_cleanse() function in crypto.h, which perfectly does the job of
clean and overwrite data.

For details see: http://www.viva64.com/en/b/0178/

- change memset() to OPENSSL_cleanse() where appropriate
- change a hard-coded number from netbase.cpp into a sizeof()
---
 src/allocators.h | 5 +++--
 src/base58.h     | 6 ++++--
 src/crypter.cpp  | 4 ++--
 src/crypter.h    | 4 ++--
 src/netbase.cpp  | 2 +-
 src/util.cpp     | 2 +-
 6 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/allocators.h b/src/allocators.h
index 99afa10c2..eb2aed672 100644
--- a/src/allocators.h
+++ b/src/allocators.h
@@ -9,6 +9,7 @@
 #include <string>
 #include <boost/thread/mutex.hpp>
 #include <map>
+#include <openssl/crypto.h> // for OPENSSL_cleanse()
 
 #ifdef WIN32
 #ifdef _WIN32_WINNT
@@ -212,7 +213,7 @@ struct secure_allocator : public std::allocator<T>
     {
         if (p != NULL)
         {
-            memset(p, 0, sizeof(T) * n);
+            OPENSSL_cleanse(p, sizeof(T) * n);
             LockedPageManager::instance.UnlockRange(p, sizeof(T) * n);
         }
         std::allocator<T>::deallocate(p, n);
@@ -246,7 +247,7 @@ struct zero_after_free_allocator : public std::allocator<T>
     void deallocate(T* p, std::size_t n)
     {
         if (p != NULL)
-            memset(p, 0, sizeof(T) * n);
+            OPENSSL_cleanse(p, sizeof(T) * n);
         std::allocator<T>::deallocate(p, n);
     }
 };
diff --git a/src/base58.h b/src/base58.h
index 9dfea86ff..309d35f5d 100644
--- a/src/base58.h
+++ b/src/base58.h
@@ -17,6 +17,8 @@
 
 #include <string>
 #include <vector>
+#include <openssl/crypto.h> // for OPENSSL_cleanse()
+
 #include "bignum.h"
 #include "key.h"
 #include "script.h"
@@ -190,7 +192,7 @@ protected:
     {
         // zero the memory, as it may contain sensitive data
         if (!vchData.empty())
-            memset(&vchData[0], 0, vchData.size());
+            OPENSSL_cleanse(&vchData[0], vchData.size());
     }
 
     void SetData(int nVersionIn, const void* pdata, size_t nSize)
@@ -221,7 +223,7 @@ public:
         vchData.resize(vchTemp.size() - 1);
         if (!vchData.empty())
             memcpy(&vchData[0], &vchTemp[1], vchData.size());
-        memset(&vchTemp[0], 0, vchTemp.size());
+        OPENSSL_cleanse(&vchTemp[0], vchData.size());
         return true;
     }
 
diff --git a/src/crypter.cpp b/src/crypter.cpp
index 181b8fa00..a2b62a87c 100644
--- a/src/crypter.cpp
+++ b/src/crypter.cpp
@@ -24,8 +24,8 @@ bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::v
 
     if (i != (int)WALLET_CRYPTO_KEY_SIZE)
     {
-        memset(&chKey, 0, sizeof chKey);
-        memset(&chIV, 0, sizeof chIV);
+        OPENSSL_cleanse(chKey, sizeof(chKey));
+        OPENSSL_cleanse(chIV, sizeof(chIV));
         return false;
     }
 
diff --git a/src/crypter.h b/src/crypter.h
index 04538a3fa..6f75170ba 100644
--- a/src/crypter.h
+++ b/src/crypter.h
@@ -76,8 +76,8 @@ public:
 
     void CleanKey()
     {
-        memset(&chKey, 0, sizeof chKey);
-        memset(&chIV, 0, sizeof chIV);
+        OPENSSL_cleanse(chKey, sizeof(chKey));
+        OPENSSL_cleanse(chIV, sizeof(chIV));
         fKeySet = false;
     }
 
diff --git a/src/netbase.cpp b/src/netbase.cpp
index 7b28e7f1b..9e7307204 100644
--- a/src/netbase.cpp
+++ b/src/netbase.cpp
@@ -545,7 +545,7 @@ bool ConnectSocketByName(CService &addr, SOCKET& hSocketRet, const char *pszDest
 
 void CNetAddr::Init()
 {
-    memset(ip, 0, 16);
+    memset(ip, 0, sizeof(ip));
 }
 
 void CNetAddr::SetIP(const CNetAddr& ipIn)
diff --git a/src/util.cpp b/src/util.cpp
index 916288645..03014a5da 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -156,7 +156,7 @@ void RandAddSeedPerfmon()
     if (ret == ERROR_SUCCESS)
     {
         RAND_add(pdata, nSize, nSize/100.0);
-        memset(pdata, 0, nSize);
+        OPENSSL_cleanse(pdata, nSize);
         printf("RandAddSeed() %lu bytes\n", nSize);
     }
 #endif

From d0b0925be9f94068deb98940103a7b8a8c56f027 Mon Sep 17 00:00:00 2001
From: Philip Kaufmann <phil.kaufmann@t-online.de>
Date: Fri, 9 Nov 2012 12:50:59 +0100
Subject: [PATCH 2/2] make CBase58Data class use zero_after_free_allocator

- this way there is no need for an explicit destructor, who does the same
  thing anyway
---
 src/base58.h | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/src/base58.h b/src/base58.h
index 309d35f5d..be8a541f6 100644
--- a/src/base58.h
+++ b/src/base58.h
@@ -17,11 +17,11 @@
 
 #include <string>
 #include <vector>
-#include <openssl/crypto.h> // for OPENSSL_cleanse()
 
 #include "bignum.h"
 #include "key.h"
 #include "script.h"
+#include "allocators.h"
 
 static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
 
@@ -180,7 +180,8 @@ protected:
     unsigned char nVersion;
 
     // the actually encoded data
-    std::vector<unsigned char> vchData;
+    typedef std::vector<unsigned char, zero_after_free_allocator<unsigned char> > vector_uchar;
+    vector_uchar vchData;
 
     CBase58Data()
     {
@@ -188,13 +189,6 @@ protected:
         vchData.clear();
     }
 
-    ~CBase58Data()
-    {
-        // zero the memory, as it may contain sensitive data
-        if (!vchData.empty())
-            OPENSSL_cleanse(&vchData[0], vchData.size());
-    }
-
     void SetData(int nVersionIn, const void* pdata, size_t nSize)
     {
         nVersion = nVersionIn;
@@ -459,4 +453,4 @@ public:
     }
 };
 
-#endif
+#endif // BITCOIN_BASE58_H