Remove deprecated random number generator functions

This commit changes CInit to check for proper RNG seeding and use
RAND_poll() if necessary.

It removes RandAddSeed() RandAddSeedPerfmon() and also the use
of RAND_screen.

src/init.cpp

@@ -1245,8 +1245,6 @@ bool AppInit2(ThreadHandlerPtr threads)
     if (fFirstRun)
     {
         // Create new keyUser and set as default key
-        RandAddSeedPerfmon();
-
         CPubKey newDefaultKey;
         if (pwalletMain->GetKeyFromPool(newDefaultKey, false)) {
             pwalletMain->SetDefaultKey(newDefaultKey);
@@ -1358,8 +1356,6 @@ bool AppInit2(ThreadHandlerPtr threads)
     if (!CheckDiskSpace())
         return false;
 
-    RandAddSeedPerfmon();
-
     if (!GRC::Initialize(threads, pindexBest)) {
         return false;
     }

src/main.cpp

@@ -2950,8 +2950,6 @@ bool static AlreadyHave(CTxDB& txdb, const CInv& inv)
 
 bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv, int64_t nTimeReceived)
 {
-    RandAddSeedPerfmon();
-
     LogPrint(BCLog::LogFlags::NOISY, "received: %s from %s (%" PRIszu " bytes)", strCommand, pfrom->addrName, vRecv.size());
 
     if (strCommand == "aries")

src/qt/winshutdownmonitor.cpp

@@ -22,16 +22,6 @@ bool WinShutdownMonitor::nativeEventFilter(const QByteArray &eventType, void *pM
 
        MSG *pMsg = static_cast<MSG *>(pMessage);
 
-       // Seed OpenSSL PRNG with Windows event data (e.g.  mouse movements and other user interactions)
-       if (RAND_event(pMsg->message, pMsg->wParam, pMsg->lParam) == 0) {
-           // Warn only once as this is performance-critical
-           static bool warned = false;
-           if (!warned) {
-               LogPrintf("%s: OpenSSL RAND_event() failed to seed OpenSSL PRNG with enough data.\n", __func__);
-               warned = true;
-           }
-       }
-
        switch(pMsg->message)
        {
            case WM_QUERYENDSESSION:

src/util.cpp

@@ -85,14 +85,27 @@ class CInit
             ppmutexOpenSSL[i] = new CCriticalSection();
         CRYPTO_set_locking_callback(locking_callback);
 
-#ifdef WIN32
-        // Seed OpenSSL PRNG with current contents of the screen
-        RAND_screen();
-#endif
+        // Check whether OpenSSL random number generator is properly seeded. If not, attempt to seed using RAND_poll().
+        // Note that in versions of OpenSSL in the depends in Gridcoin (currently 1.1.1+), and modern Unix distros (using
+        // openSSL 1.1.1+ or modern Windows operating systems with the equivalent of /dev/urandom, the random number
+        // generator is automatically seeded on init, and periodically reseeded from trusted OS random sources. It is
+        // not necessary to manually reseed the RNG. Here we implement a check via RAND_status() to ensure the RNG
+        // is properly seeded. If not, we try 10 times (probably excessive) to seed the RNG via openSSL's entropy sources,
+        // breaking as soon as the return from RAND_poll() becomes 1 (successfully seeded). If this falls through, we abort
+        // the application as we cannot have a non-functioning RNG.
+        bool seed_successful = RAND_status();
+        if (!seed_successful) {
+            for (unsigned int i = 0; i < 10; ++i)
+            {
+                seed_successful = RAND_poll();
 
-        // Seed OpenSSL PRNG with performance counter
-        RandAddSeed();
+                if (seed_successful) break;
+            }
+
+            if (!seed_successful) std::abort();
+        }
     }
+
     ~CInit()
     {
         // Securely erase the memory used by the PRNG
@@ -106,41 +119,6 @@ class CInit
 }
 instance_of_cinit;
 
-void RandAddSeed()
-{
-    // Seed with CPU performance counter
-    int64_t nCounter = GetPerformanceCounter();
-    RAND_add(&nCounter, sizeof(nCounter), 1.5);
-    memset(&nCounter, 0, sizeof(nCounter));
-}
-
-void RandAddSeedPerfmon()
-{
-    RandAddSeed();
-
-    // This can take up to 2 seconds, so only do it every 10 minutes
-    static int64_t nLastPerfmon;
-    if ( GetAdjustedTime() < nLastPerfmon + 10 * 60)
-        return;
-    nLastPerfmon =  GetAdjustedTime();
-
-#ifdef WIN32
-    // Don't need this on Linux, OpenSSL automatically uses /dev/urandom
-    // Seed with the entire set of perfmon data
-    unsigned char pdata[250000];
-    memset(pdata, 0, sizeof(pdata));
-    unsigned long nSize = sizeof(pdata);
-    long ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", nullptr, nullptr, pdata, &nSize);
-    RegCloseKey(HKEY_PERFORMANCE_DATA);
-    if (ret == ERROR_SUCCESS)
-    {
-        RAND_add(pdata, nSize, nSize/100.0);
-        memset(pdata, 0, nSize);
-        LogPrint(BCLog::LogFlags::NOISY, "rand", "RandAddSeed() %lu bytes", nSize);
-    }
-#endif
-}
-
 uint64_t GetRand(uint64_t nMax)
 {
     if (nMax == 0)

src/util.h

@@ -89,9 +89,6 @@ extern bool fLogTimestamps;
 extern bool fReopenDebugLog;
 extern bool fDevbuildCripple;
 
-void RandAddSeed();
-void RandAddSeedPerfmon();
-
 void LogException(std::exception* pex, const char* pszThread);
 void PrintException(std::exception* pex, const char* pszThread);
 void PrintExceptionContinue(std::exception* pex, const char* pszThread);

src/wallet/wallet.cpp

@@ -88,7 +88,6 @@ CPubKey CWallet::GenerateNewKey()
     AssertLockHeld(cs_wallet); // mapKeyMetadata
     bool fCompressed = CanSupportFeature(FEATURE_COMPRPUBKEY); // default to compressed public keys if we want 0.6.0 wallets
 
-    RandAddSeedPerfmon();
     CKey key;
     key.MakeNewKey(fCompressed);
 
@@ -307,14 +306,12 @@ bool CWallet::EncryptWallet(const SecureString& strWalletPassphrase)
         return false;
 
     CKeyingMaterial vMasterKey;
-    RandAddSeedPerfmon();
 
     vMasterKey.resize(WALLET_CRYPTO_KEY_SIZE);
     RAND_bytes(&vMasterKey[0], WALLET_CRYPTO_KEY_SIZE);
 
     CMasterKey kMasterKey(nDerivationMethodIndex);
 
-    RandAddSeedPerfmon();
     kMasterKey.vchSalt.resize(WALLET_CRYPTO_SALT_SIZE);
     RAND_bytes(&kMasterKey.vchSalt[0], WALLET_CRYPTO_SALT_SIZE);