test_entropy.cpp

/*
* (C) 2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include "tests.h"
#include "test_rng.h"
#include <botan/entropy_src.h>

#if defined(BOTAN_HAS_COMPRESSION)
   #include <botan/compression.h>
#endif

namespace Botan_Tests {

namespace {

class Entropy_Source_Tests final : public Test
   {
   public:
      std::vector<Test::Result> run() override
         {
         Botan::Entropy_Sources& srcs = Botan::Entropy_Sources::global_sources();

         std::vector<std::string> src_names = srcs.enabled_sources();

         std::vector<Test::Result> results;

         for(auto const& src_name : src_names)
            {
            Test::Result result("Entropy source " + src_name);

            result.start_timer();

            try
               {
               SeedCapturing_RNG rng;

               size_t bits = srcs.poll_just(rng, src_name);

               result.test_gte("Entropy estimate", rng.seed_material().size() * 8, bits);

               if(rng.samples() > 0)
                  {
                  result.test_gte("Seed material bytes", rng.seed_material().size(), 1);
                  result.test_gte("Samples", rng.samples(), 1);
                  }

               result.test_note("poll result", rng.seed_material());

#if defined(BOTAN_HAS_COMPRESSION)
               if(!rng.seed_material().empty())
                  {
                  /*
                  * Skip bzip2 both due to OS X problem (GH #394) and because bzip2's
                  * large blocks cause the entropy differential test to fail sometimes.
                  */
                  for(const std::string comp_algo : { "zlib", "lzma" })
                     {
                     std::unique_ptr<Botan::Compression_Algorithm> comp(Botan::make_compressor(comp_algo));

                     if(comp)
                        {
                        size_t comp1_size = 0;

                        try
                           {
                           Botan::secure_vector<uint8_t> compressed;
                           compressed.assign(rng.seed_material().begin(), rng.seed_material().end());
                           comp->start(9);
                           comp->finish(compressed);

                           comp1_size = compressed.size();

                           result.test_gte(comp_algo + " compressed entropy better than advertised",
                                           compressed.size() * 8, bits);
                           }
                        catch(std::exception& e)
                           {
                           result.test_failure(comp_algo + " exception while compressing", e.what());
                           }

                        SeedCapturing_RNG rng2;

                        size_t bits2 = srcs.poll_just(rng2, src_name);

                        result.test_note("poll 2 result", rng2.seed_material());

                        try
                           {
                           Botan::secure_vector<uint8_t> compressed;
                           compressed.insert(compressed.end(), rng.seed_material().begin(), rng.seed_material().end());
                           compressed.insert(compressed.end(), rng2.seed_material().begin(), rng2.seed_material().end());

                           comp->start();
                           comp->finish(compressed);

                           size_t comp2_size = compressed.size();

                           result.test_lt("Two blocks of entropy are larger than one",
                                          comp1_size, comp2_size);

                           size_t comp_diff = comp2_size - comp1_size;

                           result.test_gte(comp_algo + " diff compressed entropy better than advertised",
                                           comp_diff * 8, bits2);
                           }
                        catch(std::exception& e)
                           {
                           result.test_failure(comp_algo + " exception while compressing", e.what());
                           }
                        }
                     }
                  }
#endif
               }
            catch(std::exception& e)
               {
               result.test_failure("during entropy collection test", e.what());
               }

            result.end_timer();
            results.push_back(result);
            }

         return results;
         }
   };

BOTAN_REGISTER_TEST("entropy", Entropy_Source_Tests);

}

}