When available use RDRAND for Stateful_RNG additional data

1 files changed, 19 insertions, 4 deletions

diff --git a/src/lib/rng/stateful_rng/stateful_rng.cpp b/src/lib/rng/stateful_rng/stateful_rng.cpp
index dec791793..058245d14 100644
--- a/src/lib/rng/stateful_rng/stateful_rng.cpp
+++ b/src/lib/rng/stateful_rng/stateful_rng.cpp
@@ -8,6 +8,10 @@
 #include <botan/internal/os_utils.h>
 #include <botan/loadstor.h>
 
+#if defined(BOTAN_HAS_RDRAND_RNG)
+  #include <botan/rdrand_rng.h>
+#endif
+
 namespace Botan {
 
 void Stateful_RNG::clear()
@@ -39,10 +43,21 @@ void Stateful_RNG::initialize_with(const uint8_t input[], size_t len)
 void Stateful_RNG::randomize_with_ts_input(uint8_t output[], size_t output_len)
    {
    uint8_t additional_input[24] = { 0 };
-   store_le(OS::get_system_timestamp_ns(), additional_input);
-   store_le(OS::get_high_resolution_clock(), additional_input + 8);
-   store_le(m_last_pid, additional_input + 16);
-   store_le(static_cast<uint32_t>(m_reseed_counter), additional_input + 20);
+
+#if defined(BOTAN_HAS_RDRAND_RNG)
+   if(RDRAND_RNG::available())
+      {
+      RDRAND_RNG rdrand;
+      rdrand.randomize(additional_input, sizeof(additional_input));
+      }
+   else
+#endif
+      {
+      store_le(OS::get_system_timestamp_ns(), additional_input);
+      store_le(OS::get_high_resolution_clock(), 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));
    }