Coverage Report

Created: 2021-05-04 09:02

/src/botan/build/include/botan/hmac_drbg.h
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/*
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* HMAC_DRBG (SP800-90A)
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* (C) 2014,2015,2016 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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#ifndef BOTAN_HMAC_DRBG_H_
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#define BOTAN_HMAC_DRBG_H_
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#include <botan/stateful_rng.h>
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#include <botan/mac.h>
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namespace Botan {
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class Entropy_Sources;
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/**
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* HMAC_DRBG from NIST SP800-90A
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*/
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class BOTAN_PUBLIC_API(2,0) HMAC_DRBG final : public Stateful_RNG
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   {
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   public:
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      /**
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      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
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      *
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      * Automatic reseeding is disabled completely, as it has no access to
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      * any source for seed material.
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      *
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      * If a fork is detected, the RNG will be unable to reseed itself
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      * in response. In this case, an exception will be thrown rather
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      * than generating duplicated output.
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      */
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      explicit HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf);
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      /**
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      * Constructor taking a string for the hash
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      */
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      explicit HMAC_DRBG(const std::string& hmac_hash);
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      /**
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      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
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      *
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      * Automatic reseeding from @p underlying_rng will take place after
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      * @p reseed_interval many requests or after a fork was detected.
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      *
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      * @param prf MAC to use as a PRF
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      * @param underlying_rng is a reference to some RNG which will be used
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      * to perform the periodic reseeding
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      * @param reseed_interval specifies a limit of how many times
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      * the RNG will be called before automatic reseeding is performed (max. 2^24)
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      * @param max_number_of_bytes_per_request requests that are in size higher
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      * than max_number_of_bytes_per_request are treated as if multiple single
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      * requests of max_number_of_bytes_per_request size had been made.
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      * In theory SP 800-90A requires that we reject any request for a DRBG
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      * output longer than max_number_of_bytes_per_request. To avoid inconveniencing
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      * the caller who wants an output larger than max_number_of_bytes_per_request,
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      * instead treat these requests as if multiple requests of
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      * max_number_of_bytes_per_request size had been made. NIST requires for
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      * HMAC_DRBG that every implementation set a value no more than 2**19 bits
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      * (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
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      * example every 512 bit automatic reseeding occurs.
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      */
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      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
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                RandomNumberGenerator& underlying_rng,
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                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
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                size_t max_number_of_bytes_per_request = 64 * 1024);
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      /**
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      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
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      *
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      * Automatic reseeding from @p entropy_sources will take place after
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      * @p reseed_interval many requests or after a fork was detected.
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      *
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      * @param prf MAC to use as a PRF
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      * @param entropy_sources will be polled to perform reseeding periodically
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      * @param reseed_interval specifies a limit of how many times
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      * the RNG will be called before automatic reseeding is performed (max. 2^24)
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      * @param max_number_of_bytes_per_request requests that are in size higher
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      * than max_number_of_bytes_per_request are treated as if multiple single
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      * requests of max_number_of_bytes_per_request size had been made.
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      * In theory SP 800-90A requires that we reject any request for a DRBG
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      * output longer than max_number_of_bytes_per_request. To avoid inconveniencing
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      * the caller who wants an output larger than max_number_of_bytes_per_request,
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      * instead treat these requests as if multiple requests of
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      * max_number_of_bytes_per_request size had been made. NIST requires for
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      * HMAC_DRBG that every implementation set a value no more than 2**19 bits
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      * (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
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      * example every 512 bit automatic reseeding occurs.
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      */
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      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
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                Entropy_Sources& entropy_sources,
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                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
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                size_t max_number_of_bytes_per_request = 64 * 1024);
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      /**
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      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
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      *
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      * Automatic reseeding from @p underlying_rng and @p entropy_sources
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      * will take place after @p reseed_interval many requests or after
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      * a fork was detected.
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      *
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      * @param prf MAC to use as a PRF
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      * @param underlying_rng is a reference to some RNG which will be used
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      * to perform the periodic reseeding
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      * @param entropy_sources will be polled to perform reseeding periodically
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      * @param reseed_interval specifies a limit of how many times
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      * the RNG will be called before automatic reseeding is performed (max. 2^24)
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      * @param max_number_of_bytes_per_request requests that are in size higher
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      * than max_number_of_bytes_per_request are treated as if multiple single
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      * requests of max_number_of_bytes_per_request size had been made.
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      * In theory SP 800-90A requires that we reject any request for a DRBG
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      * output longer than max_number_of_bytes_per_request. To avoid inconveniencing
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      * the caller who wants an output larger than max_number_of_bytes_per_request,
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      * instead treat these requests as if multiple requests of
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      * max_number_of_bytes_per_request size had been made. NIST requires for
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      * HMAC_DRBG that every implementation set a value no more than 2**19 bits
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      * (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
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      * example every 512 bit automatic reseeding occurs.
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      */
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      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
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                RandomNumberGenerator& underlying_rng,
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                Entropy_Sources& entropy_sources,
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                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
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                size_t max_number_of_bytes_per_request = 64 * 1024);
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      std::string name() const override;
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      size_t security_level() const override;
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      size_t max_number_of_bytes_per_request() const override
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         { return m_max_number_of_bytes_per_request; }
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   private:
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      void update(const uint8_t input[], size_t input_len) override;
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      void generate_output(uint8_t output[], size_t output_len,
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                           const uint8_t input[], size_t input_len) override;
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      void clear_state() override;
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      std::unique_ptr<MessageAuthenticationCode> m_mac;
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      secure_vector<uint8_t> m_V;
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      const size_t m_max_number_of_bytes_per_request;
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      const size_t m_security_level;
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   };
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}
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#endif