1 files changed, 112 insertions, 0 deletions
diff --git a/src/lib/rng/stateful_rng/stateful_rng.cpp b/src/lib/rng/stateful_rng/stateful_rng.cpp
new file mode 100644
index 000000000..1349c1208
--- /dev/null
+++ b/src/lib/rng/stateful_rng/stateful_rng.cpp
@@ -0,0 +1,112 @@
+/*
+* (C) 2016 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/stateful_rng.h>
+#include <botan/internal/os_utils.h>
+#include <botan/loadstor.h>
+
+namespace Botan {
+
+void Stateful_RNG::clear()
+   {
+   m_reseed_counter = 0;
+   m_last_pid = 0;
+   }
+
+void Stateful_RNG::force_reseed()
+   {
+   m_reseed_counter = 0;
+   }
+
+bool Stateful_RNG::is_seeded() const
+   {
+   return m_reseed_counter > 0;
+   }
+
+void Stateful_RNG::initialize_with(const byte input[], size_t len)
+   {
+   add_entropy(input, len);
+
+   if(8*len >= security_level())
+      {
+      m_reseed_counter = 1;
+      }
+   }
+
+void Stateful_RNG::randomize_with_ts_input(byte output[], size_t output_len)
+   {
+   byte additional_input[24] = { 0 };
+   store_le(OS::get_system_timestamp_ns(), additional_input);
+   store_le(OS::get_processor_timestamp(), additional_input + 8);
+   store_le(m_last_pid, additional_input + 16);
+   store_le(static_cast<uint32_t>(m_reseed_counter), additional_input + 20);
+
+   randomize_with_input(output, output_len, additional_input, sizeof(additional_input));
+   }
+
+size_t Stateful_RNG::reseed(Entropy_Sources& srcs,
+                            size_t poll_bits,
+                            std::chrono::milliseconds poll_timeout)
+   {
+   size_t bits_collected = RandomNumberGenerator::reseed(srcs, poll_bits, poll_timeout);
+
+   if(bits_collected >= security_level())
+      {
+      m_reseed_counter = 1;
+      }
+
+   return bits_collected;
+   }
+
+void Stateful_RNG::reseed_from_rng(RandomNumberGenerator& rng, size_t poll_bits)
+   {
+   RandomNumberGenerator::reseed_from_rng(rng, poll_bits);
+
+   if(poll_bits >= security_level())
+      {
+      m_reseed_counter = 1;
+      }
+   }
+
+void Stateful_RNG::reseed_check()
+   {
+   const uint32_t cur_pid = OS::get_process_id();
+
+   const bool fork_detected = (m_last_pid > 0) && (cur_pid != m_last_pid);
+
+   if(is_seeded() == false ||
+      fork_detected ||
+      (m_reseed_interval > 0 && m_reseed_counter >= m_reseed_interval))
+      {
+      m_reseed_counter = 0;
+      m_last_pid = cur_pid;
+
+      if(m_underlying_rng)
+         {
+         reseed_from_rng(*m_underlying_rng, security_level());
+         }
+
+      if(m_entropy_sources)
+         {
+         reseed(*m_entropy_sources, security_level());
+         }
+
+      if(!is_seeded())
+         {
+         if(fork_detected)
+            throw Exception("Detected use of fork but cannot reseed DRBG");
+         else
+            throw PRNG_Unseeded(name());
+         }
+      }
+   else
+      {
+      BOTAN_ASSERT(m_reseed_counter != 0, "RNG is seeded");
+      m_reseed_counter += 1;
+      }
+   }
+
+}