Add a cmdlet which allows sampling/testing raw entropy sources

1 files changed, 104 insertions, 0 deletions

diff --git a/src/cli/entropy.cpp b/src/cli/entropy.cpp
new file mode 100644
index 000000000..0404afb99
--- /dev/null
+++ b/src/cli/entropy.cpp
@@ -0,0 +1,104 @@
+/*
+* (C) 2019 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include "cli.h"
+#include "../tests/test_rng.h" // FIXME
+
+#include <botan/entropy_src.h>
+
+#if defined(BOTAN_HAS_COMPRESSION)
+#include <botan/compression.h>
+#endif
+
+namespace Botan_CLI {
+
+class Entropy final : public Command
+   {
+   public:
+      Entropy() : Command("entropy --truncate-at=128 source") {}
+
+      std::string group() const override
+         {
+         return "misc";
+         }
+
+      std::string description() const override
+         {
+         return "Sample a raw entropy source";
+         }
+
+      void go() override
+         {
+         const std::string req_source = get_arg("source");
+         const size_t truncate_sample = get_arg_sz("truncate-at");
+
+         auto& entropy_sources = Botan::Entropy_Sources::global_sources();
+
+         std::vector<std::string> sources;
+         if(req_source == "all")
+            sources = entropy_sources.enabled_sources();
+         else
+            sources.push_back(req_source);
+
+         for(std::string source : sources)
+            {
+            Botan_Tests::SeedCapturing_RNG rng;
+            const size_t entropy_estimate = entropy_sources.poll_just(rng, source);
+
+            if(rng.samples() == 0)
+               {
+               output() << "Source " << source << " is unavailable\n";
+               continue;
+               }
+
+            const auto& sample = rng.seed_material();
+
+            output() << "Polling " << source << " gathered " << sample.size()
+                     << " bytes in " << rng.samples() << " outputs with estimated entropy "
+                     << entropy_estimate << "\n";
+
+#if defined(BOTAN_HAS_COMPRESSION)
+            if(!sample.empty())
+               {
+               std::unique_ptr<Botan::Compression_Algorithm> comp(Botan::make_compressor("zlib"));
+               if(comp)
+                  {
+                  try
+                     {
+                     Botan::secure_vector<uint8_t> compressed;
+                     compressed.assign(sample.begin(), sample.end());
+                     comp->start(9);
+                     comp->finish(compressed);
+
+                     if(compressed.size() < sample.size())
+                        {
+                        output() << "Sample from " << source << " was zlib compressed from " << sample.size()
+                                 << " bytes to " << compressed.size() << " bytes\n";
+                        }
+                     }
+                  catch(std::exception& e)
+                     {
+                     error_output() << "Error while attempting to compress: " << e.what() << "\n";
+                     }
+                  }
+               }
+#endif
+
+            if(sample.size() <= truncate_sample)
+               {
+               output() << Botan::hex_encode(sample) << "\n";
+               }
+            else if(truncate_sample > 0)
+               {
+               output() << Botan::hex_encode(&sample[0], truncate_sample) << "...\n";
+               }
+            }
+         }
+   };
+
+BOTAN_REGISTER_COMMAND("entropy", Entropy);
+
+}