Coverage Report

Created: 2020-05-23 13:54

/src/botan/src/lib/rng/chacha_rng/chacha_rng.cpp
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/*
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* ChaCha_RNG
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* (C) 2017 Jack Lloyd
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*
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* Botan is released under the Simplified BSD License (see license.txt)
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*/
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#include <botan/chacha_rng.h>
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namespace Botan {
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ChaCha_RNG::ChaCha_RNG() : Stateful_RNG()
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   {
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   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
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   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
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   clear();
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   }
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ChaCha_RNG::ChaCha_RNG(const secure_vector<uint8_t>& seed) : Stateful_RNG()
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   {
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   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
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   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
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   clear();
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   add_entropy(seed.data(), seed.size());
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   }
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ChaCha_RNG::ChaCha_RNG(RandomNumberGenerator& underlying_rng,
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                       size_t reseed_interval) :
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   Stateful_RNG(underlying_rng, reseed_interval)
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   {
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   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
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   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
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   clear();
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   }
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ChaCha_RNG::ChaCha_RNG(RandomNumberGenerator& underlying_rng,
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                       Entropy_Sources& entropy_sources,
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                       size_t reseed_interval) :
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   Stateful_RNG(underlying_rng, entropy_sources, reseed_interval)
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   {
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   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
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   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
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   clear();
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   }
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ChaCha_RNG::ChaCha_RNG(Entropy_Sources& entropy_sources,
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                       size_t reseed_interval) :
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   Stateful_RNG(entropy_sources, reseed_interval)
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   {
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   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
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   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
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   clear();
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   }
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void ChaCha_RNG::clear()
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   {
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   Stateful_RNG::clear();
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   m_hmac->set_key(std::vector<uint8_t>(m_hmac->output_length(), 0x00));
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   m_chacha->set_key(m_hmac->final());
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   }
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void ChaCha_RNG::randomize(uint8_t output[], size_t output_len)
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   {
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   randomize_with_input(output, output_len, nullptr, 0);
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   }
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void ChaCha_RNG::randomize_with_input(uint8_t output[], size_t output_len,
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                                      const uint8_t input[], size_t input_len)
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   {
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   reseed_check();
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   if(input_len > 0)
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      {
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      update(input, input_len);
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      }
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   m_chacha->write_keystream(output, output_len);
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   }
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void ChaCha_RNG::update(const uint8_t input[], size_t input_len)
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   {
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   m_hmac->update(input, input_len);
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   m_chacha->set_key(m_hmac->final());
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   secure_vector<uint8_t> mac_key(m_hmac->output_length());
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   m_chacha->write_keystream(mac_key.data(), mac_key.size());
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   m_hmac->set_key(mac_key);
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   }
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void ChaCha_RNG::add_entropy(const uint8_t input[], size_t input_len)
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   {
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   update(input, input_len);
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   if(8*input_len >= security_level())
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      {
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      reset_reseed_counter();
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      }
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   }
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size_t ChaCha_RNG::security_level() const
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   {
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   return 256;
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   }
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}