1 files changed, 101 insertions, 0 deletions
diff --git a/src/lib/rng/chacha_rng/chacha_rng.cpp b/src/lib/rng/chacha_rng/chacha_rng.cpp
new file mode 100644
index 000000000..86c71f9fe
--- /dev/null
+++ b/src/lib/rng/chacha_rng/chacha_rng.cpp
@@ -0,0 +1,101 @@
+/*
+* ChaCha_RNG
+* (C) 2017 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/chacha_rng.h>
+
+namespace Botan {
+
+ChaCha_RNG::ChaCha_RNG() : Stateful_RNG()
+   {
+   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
+   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
+   clear();
+   }
+
+ChaCha_RNG::ChaCha_RNG(const secure_vector<uint8_t>& seed) : Stateful_RNG()
+   {
+   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
+   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
+   clear();
+   add_entropy(seed.data(), seed.size());
+   }
+
+ChaCha_RNG::ChaCha_RNG(RandomNumberGenerator& underlying_rng,
+                       size_t reseed_interval) :
+   Stateful_RNG(underlying_rng, reseed_interval)
+   {
+   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
+   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
+   clear();
+   }
+
+ChaCha_RNG::ChaCha_RNG(RandomNumberGenerator& underlying_rng,
+                       Entropy_Sources& entropy_sources,
+                       size_t reseed_interval) :
+   Stateful_RNG(underlying_rng, entropy_sources, reseed_interval)
+   {
+   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
+   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
+   clear();
+   }
+
+ChaCha_RNG::ChaCha_RNG(Entropy_Sources& entropy_sources,
+                       size_t reseed_interval) :
+   Stateful_RNG(entropy_sources, reseed_interval)
+   {
+   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
+   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
+   clear();
+   }
+
+void ChaCha_RNG::clear()
+   {
+   Stateful_RNG::clear();
+
+   m_hmac->set_key(std::vector<uint8_t>(m_hmac->output_length(), 0x00));
+   m_chacha->set_key(m_hmac->final());
+   }
+
+void ChaCha_RNG::randomize(uint8_t output[], size_t output_len)
+   {
+   randomize_with_input(output, output_len, nullptr, 0);
+   }
+
+void ChaCha_RNG::randomize_with_input(uint8_t output[], size_t output_len,
+                                      const uint8_t input[], size_t input_len)
+   {
+   add_entropy(input, input_len);
+   reseed_check();
+
+   clear_mem(output, output_len);
+   m_chacha->cipher1(output, output_len);
+   }
+
+void ChaCha_RNG::add_entropy(const uint8_t input[], size_t input_len)
+   {
+   if(input_len > 0)
+      {
+      m_hmac->update(input, input_len);
+      m_chacha->set_key(m_hmac->final());
+
+      secure_vector<uint8_t> mac_key(m_hmac->output_length());
+      m_chacha->cipher1(mac_key.data(), mac_key.size());
+      m_hmac->set_key(mac_key);
+
+      if(8*input_len >= security_level())
+         {
+         m_reseed_counter = 1;
+         }
+      }
+   }
+
+size_t ChaCha_RNG::security_level() const
+   {
+   return 256;
+   }
+
+}