4.44 beta

CPP/7zip/Crypto/Hash/RandGen.cpp

@@ -0,0 +1,78 @@
+// RandGen.cpp
+
+#include "StdAfx.h"
+
+#include <stdio.h>
+
+#include "Windows/Synchronization.h"
+
+#include "RandGen.h"
+
+// This is not very good random number generator.
+// Please use it only for salt.
+// First genrated data block depends from timer.
+// Other genrated data blocks depend from previous state
+// Maybe it's possible to restore original timer vaue from generated value.
+
+void CRandomGenerator::Init()
+{ 
+  NCrypto::NSha1::CContext hash;
+  hash.Init();
+
+  #ifdef _WIN32
+  DWORD w = ::GetCurrentProcessId();
+  hash.Update((const Byte *)&w, sizeof(w));
+  w = ::GetCurrentThreadId();
+  hash.Update((const Byte *)&w, sizeof(w));
+  #endif
+
+  for (int i = 0; i < 1000; i++)
+  {
+    #ifdef _WIN32
+    LARGE_INTEGER v;
+    if (::QueryPerformanceCounter(&v))
+      hash.Update((const Byte *)&v.QuadPart, sizeof(v.QuadPart));
+    #endif
+
+    DWORD tickCount = ::GetTickCount();
+    hash.Update((const Byte *)&tickCount, sizeof(tickCount));
+    
+    for (int j = 0; j < 100; j++)
+    {
+      hash.Final(_buff);
+      hash.Init();
+      hash.Update(_buff, NCrypto::NSha1::kDigestSize);
+    }
+  }
+  hash.Final(_buff);
+  _needInit = false;
+}
+
+static NWindows::NSynchronization::CCriticalSection g_CriticalSection;
+
+void CRandomGenerator::Generate(Byte *data, unsigned int size)
+{ 
+  g_CriticalSection.Enter();
+  if (_needInit)
+    Init();
+  while (size > 0)
+  {
+    NCrypto::NSha1::CContext hash;
+    
+    hash.Init();
+    hash.Update(_buff, NCrypto::NSha1::kDigestSize);
+    hash.Final(_buff);
+    
+    hash.Init();
+    UInt32 salt = 0xF672ABD1;
+    hash.Update((const Byte *)&salt, sizeof(salt));
+    hash.Update(_buff, NCrypto::NSha1::kDigestSize);
+    Byte buff[NCrypto::NSha1::kDigestSize];
+    hash.Final(buff);
+    for (unsigned int i = 0; i < NCrypto::NSha1::kDigestSize && size > 0; i++, size--)
+      *data++ = buff[i];
+  }
+  g_CriticalSection.Leave();
+}
+
+CRandomGenerator g_RandomGenerator;