Common: Add Random utilities

This makes it easier to generate random numbers or fill a buffer with
random data in a cryptographically secure way.

This also replaces existing usages of RNG functions in the codebase:

* <random> is pretty hard to use correctly, and std::random_device does
  not give enough guarantees about its results (it's
  implementation-defined, non cryptographically secure and could be
  deterministic on some platforms).
  Doing things correctly is error prone and verbose.

* rand() is terrible and should not be used especially in crypto code.

1 files changed, 2 insertions, 7 deletions

diff --git a/Source/Core/Common/Network.cpp b/Source/Core/Common/Network.cpp
index f492efd5ae..1d95e0c8a4 100644
--- a/Source/Core/Common/Network.cpp
+++ b/Source/Core/Common/Network.cpp
@@ -5,11 +5,10 @@
 #include <cctype>
 #include <cstring>
 #include <ctime>
-#include <random>
 
 #include "Common/Network.h"
+#include "Common/Random.h"
 #include "Common/StringUtil.h"
-#include "Common/Timer.h"
 
 namespace Common
 {
@@ -31,11 +30,7 @@ void GenerateMacAddress(const MACConsumer type, u8* mac)
   }
 
   // Generate the 24-bit NIC-specific portion of the MAC address.
-  std::default_random_engine generator(Common::Timer::GetTimeMs());
-  std::uniform_int_distribution<int> distribution(0x00, 0xFF);
-  mac[3] = static_cast<u8>(distribution(generator));
-  mac[4] = static_cast<u8>(distribution(generator));
-  mac[5] = static_cast<u8>(distribution(generator));
+  Common::Random::Generate(&mac[3], 3);
 }
 
 std::string MacAddressToString(const u8* mac)