From 999e4c91c2cd93f4cd8760b3572780c9d568f2f0 Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Sun, 18 Sep 2016 08:23:29 +0200
Subject: wallet: Change CCrypter to use vectors with secure allocator

Change CCrypter to use vectors with secure allocator instead of buffers
on in the object itself which will end up on the stack. This avoids
having to call LockedPageManager to lock stack memory pages to prevent the
memory from being swapped to disk. This is wasteful.
---
 src/wallet/crypter.h | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

(limited to 'src/wallet/crypter.h')

diff --git a/src/wallet/crypter.h b/src/wallet/crypter.h
index 5d0a4a3305..f00f7fa731 100644
--- a/src/wallet/crypter.h
+++ b/src/wallet/crypter.h
@@ -77,8 +77,8 @@ class CCrypter
 {
 friend class wallet_crypto::TestCrypter; // for test access to chKey/chIV
 private:
-    unsigned char chKey[WALLET_CRYPTO_KEY_SIZE];
-    unsigned char chIV[WALLET_CRYPTO_IV_SIZE];
+    std::vector<unsigned char, secure_allocator<unsigned char>> vchKey;
+    std::vector<unsigned char, secure_allocator<unsigned char>> vchIV;
     bool fKeySet;
 
     int BytesToKeySHA512AES(const std::vector<unsigned char>& chSalt, const SecureString& strKeyData, int count, unsigned char *key,unsigned char *iv) const;
@@ -91,28 +91,21 @@ public:
 
     void CleanKey()
     {
-        memory_cleanse(chKey, sizeof(chKey));
-        memory_cleanse(chIV, sizeof(chIV));
+        memory_cleanse(vchKey.data(), vchKey.size());
+        memory_cleanse(vchIV.data(), vchIV.size());
         fKeySet = false;
     }
 
     CCrypter()
     {
         fKeySet = false;
-
-        // Try to keep the key data out of swap (and be a bit over-careful to keep the IV that we don't even use out of swap)
-        // Note that this does nothing about suspend-to-disk (which will put all our key data on disk)
-        // Note as well that at no point in this program is any attempt made to prevent stealing of keys by reading the memory of the running process.
-        LockedPageManager::Instance().LockRange(&chKey[0], sizeof chKey);
-        LockedPageManager::Instance().LockRange(&chIV[0], sizeof chIV);
+        vchKey.resize(WALLET_CRYPTO_KEY_SIZE);
+        vchIV.resize(WALLET_CRYPTO_IV_SIZE);
     }
 
     ~CCrypter()
     {
         CleanKey();
-
-        LockedPageManager::Instance().UnlockRange(&chKey[0], sizeof chKey);
-        LockedPageManager::Instance().UnlockRange(&chIV[0], sizeof chIV);
     }
 };
 
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