core: use C++11 <random> instead of Boost.Random

Change-Id: I8f22965b86c681581762a47995f29f888421a558
Refs: #3599
diff --git a/core/random.cpp b/core/random.cpp
index c398f8d..9c5de40 100644
--- a/core/random.cpp
+++ b/core/random.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014-2015,  Regents of the University of California,
+ * Copyright (c) 2014-2016,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -28,21 +28,15 @@
 
 namespace nfd {
 
-static boost::thread_specific_ptr<boost::random::mt19937> g_rng;
-
-boost::random::mt19937&
+std::mt19937&
 getGlobalRng()
 {
-  if (g_rng.get() == nullptr) {
-    g_rng.reset(new boost::random::mt19937());
+  static boost::thread_specific_ptr<std::mt19937> rng;
+  if (rng.get() == nullptr) {
+    std::random_device rd;
+    rng.reset(new std::mt19937(rd()));
   }
-  return *g_rng;
-}
-
-void
-resetGlobalRng()
-{
-  g_rng.reset();
+  return *rng;
 }
 
 } // namespace nfd
diff --git a/core/random.hpp b/core/random.hpp
index 1515b72..03ae9d3 100644
--- a/core/random.hpp
+++ b/core/random.hpp
@@ -1,12 +1,12 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014,  Regents of the University of California,
- *                      Arizona Board of Regents,
- *                      Colorado State University,
- *                      University Pierre & Marie Curie, Sorbonne University,
- *                      Washington University in St. Louis,
- *                      Beijing Institute of Technology,
- *                      The University of Memphis
+ * Copyright (c) 2014-2016,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
  *
  * This file is part of NFD (Named Data Networking Forwarding Daemon).
  * See AUTHORS.md for complete list of NFD authors and contributors.
@@ -24,24 +24,26 @@
  */
 
 /**
- * This file declares the global random number generator
- * All random numbers in NFD should use this global random number generator,
- * so that the generator can be properly seeded when necessary.
+ * This file declares the global pseudorandom number generator (PRNG).
  *
- * This random number generator is not suitable for security purposes;
- * security-critical code should use CryptoPP random number generator instead.
+ * All random numbers generated by NFD should use this global generator,
+ * so that it can be properly seeded when necessary.
+ *
+ * This PRNG is not suitable for security purposes; security-critical
+ * code must use a cryptographically secure PRNG, such as those provided
+ * by OpenSSL and Crypto++.
  */
 
 #ifndef NFD_CORE_RANDOM_HPP
 #define NFD_CORE_RANDOM_HPP
 
-#include <boost/random/mersenne_twister.hpp>
+#include <random>
 
 namespace nfd {
 
 /** \return the global random number generator instance
  */
-boost::random::mt19937&
+std::mt19937&
 getGlobalRng();
 
 } // namespace nfd