/* * EntropySource * (C) 2008-2009,2014 Jack Lloyd * * Distributed under the terms of the Botan license */ #ifndef BOTAN_ENTROPY_SOURCE_BASE_H__ #define BOTAN_ENTROPY_SOURCE_BASE_H__ #include #include #include namespace Botan { /** * Class used to accumulate the poll results of EntropySources */ class BOTAN_DLL Entropy_Accumulator { public: /** * Initialize an Entropy_Accumulator * @param goal is how many bits we would like to collect */ Entropy_Accumulator(std::function accum) : m_accum_fn(accum), m_done(false) {} virtual ~Entropy_Accumulator() {} /** * Get a cached I/O buffer (purely for minimizing allocation * overhead to polls) * * @param size requested size for the I/O buffer * @return cached I/O buffer for repeated polls */ secure_vector& get_io_buffer(size_t size) { m_io_buffer.clear(); m_io_buffer.resize(size); return m_io_buffer; } /** * @return if our polling goal has been achieved */ bool polling_goal_achieved() const { return m_done; } /** * Add entropy to the accumulator * @param bytes the input bytes * @param length specifies how many bytes the input is * @param entropy_bits_per_byte is a best guess at how much * entropy per byte is in this input */ void add(const void* bytes, size_t length, double entropy_bits_per_byte) { m_done = m_accum_fn(reinterpret_cast(bytes), length, entropy_bits_per_byte * length); } /** * Add entropy to the accumulator * @param v is some value * @param entropy_bits_per_byte is a best guess at how much * entropy per byte is in this input */ template void add(const T& v, double entropy_bits_per_byte) { add(&v, sizeof(T), entropy_bits_per_byte); } private: std::function m_accum_fn; bool m_done; secure_vector m_io_buffer; }; /** * Abstract interface to a source of entropy */ class BOTAN_DLL EntropySource { public: /** * @return name identifying this entropy source */ virtual std::string name() const = 0; /** * Perform an entropy gathering poll * @param accum is an accumulator object that will be given entropy */ virtual void poll(Entropy_Accumulator& accum) = 0; virtual ~EntropySource() {} }; } #endif