Newhope is really limited by RNG speed.

4x-8x overall speedup switching from HMAC_DRBG to ChaCha20

1 files changed, 33 insertions, 5 deletions

diff --git a/src/cli/speed.cpp b/src/cli/speed.cpp
index 651226d70..10408a5ae 100644
--- a/src/cli/speed.cpp
+++ b/src/cli/speed.cpp
@@ -83,8 +83,9 @@
   #include <botan/mceliece.h>
 #endif
 
-#if defined(BOTAN_HAS_NEWHOPE)
+#if defined(BOTAN_HAS_NEWHOPE) && defined(BOTAN_HAS_CHACHA)
   #include <botan/newhope.h>
+  #include <botan/chacha.h>
 #endif
 
 namespace Botan_CLI {
@@ -401,7 +402,7 @@ class Speed final : public Command
                bench_mceliece(provider, msec);
                }
 #endif
-#if defined(BOTAN_HAS_NEWHOPE)
+#if defined(BOTAN_HAS_NEWHOPE) && defined(BOTAN_HAS_CHACHA)
             else if(algo == "NEWHOPE")
                {
                bench_newhope(provider, msec);
@@ -1089,7 +1090,7 @@ class Speed final : public Command
          }
 #endif
 
-#if defined(BOTAN_HAS_NEWHOPE)
+#if defined(BOTAN_HAS_NEWHOPE) && defined(BOTAN_HAS_CHACHA)
       void bench_newhope(const std::string& provider,
                          std::chrono::milliseconds msec)
          {
@@ -1099,6 +1100,33 @@ class Speed final : public Command
          Timer shareda_timer(nm, "", "shareda");
          Timer sharedb_timer(nm, "", "sharedb");
 
+         class ChaCha20_RNG : public Botan::RandomNumberGenerator
+            {
+            public:
+               std::string name() const override { return "ChaCha20_RNG"; }
+               void clear() override { /* ignored */ }
+
+               void randomize(uint8_t out[], size_t len) override
+                  {
+                  Botan::clear_mem(out, len);
+                  m_chacha.cipher1(out, len);
+                  }
+
+               bool is_seeded() const override { return true; }
+
+               void add_entropy(const uint8_t[], size_t) override { /* ignored */ }
+
+               ChaCha20_RNG(const Botan::secure_vector<uint8_t>& seed)
+                  {
+                  m_chacha.set_key(seed);
+                  }
+
+            private:
+               Botan::ChaCha m_chacha;
+            };
+
+         ChaCha20_RNG nh_rng(rng().random_vec(32));
+
          while(sharedb_timer.under(msec))
             {
             std::vector<uint8_t> send_a(NEWHOPE_SENDABYTES), send_b(NEWHOPE_SENDBBYTES);
@@ -1107,11 +1135,11 @@ class Speed final : public Command
             Botan::newhope_poly sk_a;
 
             keygen_timer.start();
-            Botan::newhope_keygen(send_a.data(), &sk_a, rng());
+            Botan::newhope_keygen(send_a.data(), &sk_a, nh_rng);
             keygen_timer.stop();
 
             sharedb_timer.start();
-            Botan::newhope_sharedb(shared_b.data(), send_b.data(), send_a.data(), rng());
+            Botan::newhope_sharedb(shared_b.data(), send_b.data(), send_a.data(), nh_rng);
             sharedb_timer.stop();
 
             shareda_timer.start();