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Diffstat (limited to 'comm/third_party/botan/src/lib/rng/stateful_rng/stateful_rng.h')
-rw-r--r-- | comm/third_party/botan/src/lib/rng/stateful_rng/stateful_rng.h | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/rng/stateful_rng/stateful_rng.h b/comm/third_party/botan/src/lib/rng/stateful_rng/stateful_rng.h new file mode 100644 index 0000000000..e1311fcc9f --- /dev/null +++ b/comm/third_party/botan/src/lib/rng/stateful_rng/stateful_rng.h @@ -0,0 +1,166 @@ +/* +* (C) 2016 Jack Lloyd +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#ifndef BOTAN_STATEFUL_RNG_H_ +#define BOTAN_STATEFUL_RNG_H_ + +#include <botan/rng.h> +#include <botan/mutex.h> + +namespace Botan { + +/** +* Inherited by RNGs which maintain in-process state, like HMAC_DRBG. +* On Unix these RNGs are vulnerable to problems with fork, where the +* RNG state is duplicated, and the parent and child process RNGs will +* produce identical output until one of them reseeds. Stateful_RNG +* reseeds itself whenever a fork is detected, or after a set number of +* bytes have been output. +* +* Not implemented by RNGs which access an external RNG, such as the +* system PRNG or a hardware RNG. +*/ +class BOTAN_PUBLIC_API(2,0) Stateful_RNG : public RandomNumberGenerator + { + public: + /** + * @param rng is a reference to some RNG which will be used + * to perform the periodic reseeding + * @param entropy_sources will be polled to perform reseeding periodically + * @param reseed_interval specifies a limit of how many times + * the RNG will be called before automatic reseeding is performed + */ + Stateful_RNG(RandomNumberGenerator& rng, + Entropy_Sources& entropy_sources, + size_t reseed_interval) : + m_underlying_rng(&rng), + m_entropy_sources(&entropy_sources), + m_reseed_interval(reseed_interval) + {} + + /** + * @param rng is a reference to some RNG which will be used + * to perform the periodic reseeding + * @param reseed_interval specifies a limit of how many times + * the RNG will be called before automatic reseeding is performed + */ + Stateful_RNG(RandomNumberGenerator& rng, size_t reseed_interval) : + m_underlying_rng(&rng), + m_reseed_interval(reseed_interval) + {} + + /** + * @param entropy_sources will be polled to perform reseeding periodically + * @param reseed_interval specifies a limit of how many times + * the RNG will be called before automatic reseeding is performed + */ + Stateful_RNG(Entropy_Sources& entropy_sources, size_t reseed_interval) : + m_entropy_sources(&entropy_sources), + m_reseed_interval(reseed_interval) + {} + + /** + * In this case, automatic reseeding is impossible + */ + Stateful_RNG() : m_reseed_interval(0) {} + + /** + * Consume this input and mark the RNG as initialized regardless + * of the length of the input or the current seeded state of + * the RNG. + */ + void initialize_with(const uint8_t input[], size_t length); + + bool is_seeded() const override final; + + bool accepts_input() const override final { return true; } + + /** + * Mark state as requiring a reseed on next use + */ + void force_reseed(); + + void reseed_from_rng(RandomNumberGenerator& rng, + size_t poll_bits = BOTAN_RNG_RESEED_POLL_BITS) override final; + + void add_entropy(const uint8_t input[], size_t input_len) override final; + + void randomize(uint8_t output[], size_t output_len) override final; + + void randomize_with_input(uint8_t output[], size_t output_len, + const uint8_t input[], size_t input_len) override final; + + /** + * Overrides default implementation and also includes the current + * process ID and the reseed counter. + */ + void randomize_with_ts_input(uint8_t output[], size_t output_len) override final; + + /** + * Poll provided sources for up to poll_bits bits of entropy + * or until the timeout expires. Returns estimate of the number + * of bits collected. + */ + size_t reseed(Entropy_Sources& srcs, + size_t poll_bits = BOTAN_RNG_RESEED_POLL_BITS, + std::chrono::milliseconds poll_timeout = BOTAN_RNG_RESEED_DEFAULT_TIMEOUT) override; + + /** + * @return intended security level of this DRBG + */ + virtual size_t security_level() const = 0; + + /** + * Some DRBGs have a notion of the maximum number of bytes per + * request. Longer requests (to randomize) will be treated as + * multiple requests, and may initiate reseeding multiple times, + * depending on the values of max_number_of_bytes_per_request and + * reseed_interval(). This function returns zero if the RNG in + * question does not have such a notion. + * + * @return max number of bytes per request (or zero) + */ + virtual size_t max_number_of_bytes_per_request() const = 0; + + size_t reseed_interval() const { return m_reseed_interval; } + + void clear() override final; + + protected: + void reseed_check(); + + virtual void generate_output(uint8_t output[], size_t output_len, + const uint8_t input[], size_t input_len) = 0; + + virtual void update(const uint8_t input[], size_t input_len) = 0; + + virtual void clear_state() = 0; + + private: + void reset_reseed_counter(); + + mutable recursive_mutex_type m_mutex; + + // A non-owned and possibly null pointer to shared RNG + RandomNumberGenerator* m_underlying_rng = nullptr; + + // A non-owned and possibly null pointer to a shared Entropy_Source + Entropy_Sources* m_entropy_sources = nullptr; + + const size_t m_reseed_interval; + uint32_t m_last_pid = 0; + + /* + * Set to 1 after a successful seeding, then incremented. Reset + * to 0 by clear() or a fork. This logic is used even if + * automatic reseeding is disabled (via m_reseed_interval = 0) + */ + size_t m_reseed_counter = 0; + }; + +} + +#endif |