Change X9.31 to automatically reseed if randomize is called while unseeded.

If no entropy sources at all are enabled in the build, throw an exception
immediately rather than having the poll mysteriously fail.

2 files changed, 15 insertions, 10 deletions

diff --git a/src/lib/libstate/entropy_srcs.cpp b/src/lib/libstate/entropy_srcs.cpp
index b6dc6b559..44bf7b2e2 100644
--- a/src/lib/libstate/entropy_srcs.cpp
+++ b/src/lib/libstate/entropy_srcs.cpp
@@ -106,16 +106,16 @@ void Library_State::poll_available_sources(class Entropy_Accumulator& accum)
 
    const size_t poll_bits = accum.desired_remaining_bits();
 
-   if(!m_sources.empty())
+   if(m_sources.empty())
+      throw std::runtime_error("No entropy sources enabled at build time, poll failed");
+
+   size_t poll_attempt = 0;
+
+   while(!accum.polling_goal_achieved() && poll_attempt < poll_bits)
       {
-      size_t poll_attempt = 0;
-
-      while(!accum.polling_goal_achieved() && poll_attempt < poll_bits)
-         {
-         const size_t src_idx = poll_attempt % m_sources.size();
-         m_sources[src_idx]->poll(accum);
-         ++poll_attempt;
-         }
+      const size_t src_idx = poll_attempt % m_sources.size();
+      m_sources[src_idx]->poll(accum);
+      ++poll_attempt;
       }
    }
 
diff --git a/src/lib/rng/x931_rng/x931_rng.cpp b/src/lib/rng/x931_rng/x931_rng.cpp
index dbf09b367..a77ac2ca8 100644
--- a/src/lib/rng/x931_rng/x931_rng.cpp
+++ b/src/lib/rng/x931_rng/x931_rng.cpp
@@ -14,7 +14,12 @@ namespace Botan {
 void ANSI_X931_RNG::randomize(byte out[], size_t length)
    {
    if(!is_seeded())
-      throw PRNG_Unseeded(name());
+      {
+      reseed(BOTAN_RNG_RESEED_POLL_BITS);
+
+      if(!is_seeded())
+         throw PRNG_Unseeded(name());
+      }
 
    while(length)
       {