Botan::Stateful_RNG Class Reference

#include <stateful_rng.h>

Inheritance diagram for Botan::Stateful_RNG:

Public Member Functions
bool	accepts_input () const final
void	add_entropy (const uint8_t input[], size_t length)
void	add_entropy (std::span< const uint8_t > input)
template<typename T>
void	add_entropy_T (const T &t)
void	clear () final
void	force_reseed ()
void	initialize_with (const uint8_t input[], size_t length)
void	initialize_with (std::span< const uint8_t > input)
bool	is_seeded () const final
virtual size_t	max_number_of_bytes_per_request () const =0
virtual std::string	name () const =0
uint8_t	next_byte ()
uint8_t	next_nonzero_byte ()
template<size_t bytes>
std::array< uint8_t, bytes >	random_array ()
template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>
T	random_vec (size_t bytes)
void	random_vec (std::span< uint8_t > v)
template<concepts::resizable_byte_buffer T>
void	random_vec (T &v, size_t bytes)
void	randomize (std::span< uint8_t > output)
void	randomize (uint8_t output[], size_t length)
void	randomize_with_input (std::span< uint8_t > output, std::span< const uint8_t > input)
void	randomize_with_input (uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)
void	randomize_with_ts_input (std::span< uint8_t > output)
void	randomize_with_ts_input (uint8_t output[], size_t output_len)
size_t	reseed (Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits, std::chrono::milliseconds=DefaultPollTimeout)
size_t	reseed_from (Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
void	reseed_from (RandomNumberGenerator &rng, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
void	reseed_from_rng (RandomNumberGenerator &rng, size_t poll_bits=RandomNumberGenerator::DefaultPollBits) final
size_t	reseed_from_sources (Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits) final
size_t	reseed_interval () const
virtual size_t	security_level () const =0
	Stateful_RNG ()
	Stateful_RNG (Entropy_Sources &entropy_sources, size_t reseed_interval)
	Stateful_RNG (RandomNumberGenerator &rng, Entropy_Sources &entropy_sources, size_t reseed_interval)
	Stateful_RNG (RandomNumberGenerator &rng, size_t reseed_interval)

Static Public Attributes
static constexpr size_t	DefaultPollBits = 256
static constexpr auto	DefaultPollTimeout = std::chrono::milliseconds(50)
static constexpr size_t	DefaultReseedInterval = 1024

Protected Member Functions
virtual void	clear_state ()=0
virtual void	generate_output (std::span< uint8_t > output, std::span< const uint8_t > input)=0
void	reseed_check ()
virtual void	update (std::span< const uint8_t > input)=0

Detailed Description

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.

Definition at line 26 of file stateful_rng.h.

Constructor & Destructor Documentation

Stateful_RNG() [1/4]

Botan::Stateful_RNG::Stateful_RNG ( RandomNumberGenerator & rng, Entropy_Sources & entropy_sources, size_t reseed_interval )

inline

Create a Stateful_RNG which reseeds from both an RNG and entropy sources

Parameters

Random Number Generators	is a reference to some RNG which will be used to perform the periodic reseeding
entropy_sources	will be polled to perform reseeding periodically
reseed_interval	specifies a limit of how many times the RNG will be called before automatic reseeding is performed

Definition at line 37 of file stateful_rng.h.

                                                                                                         :
            m_underlying_rng(&rng), m_entropy_sources(&entropy_sources), m_reseed_interval(reseed_interval) {}

References Botan::RandomNumberGenerator::RandomNumberGenerator(), and reseed_interval().

Referenced by Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), and Botan::HMAC_DRBG::HMAC_DRBG().

Stateful_RNG() [2/4]

Botan::Stateful_RNG::Stateful_RNG ( RandomNumberGenerator & rng, size_t reseed_interval )

inline

Create a Stateful_RNG which reseeds from another RNG

Parameters

Random Number Generators	is a reference to some RNG which will be used to perform the periodic reseeding
reseed_interval	specifies a limit of how many times the RNG will be called before automatic reseeding is performed

Definition at line 48 of file stateful_rng.h.

                                                                       :
            m_underlying_rng(&rng), m_reseed_interval(reseed_interval) {}

References Botan::RandomNumberGenerator::RandomNumberGenerator(), and reseed_interval().

Stateful_RNG() [3/4]

Botan::Stateful_RNG::Stateful_RNG ( Entropy_Sources & entropy_sources, size_t reseed_interval )

inline

Create a Stateful_RNG which reseeds from entropy sources

Parameters

entropy_sources	will be polled to perform reseeding periodically
reseed_interval	specifies a limit of how many times the RNG will be called before automatic reseeding is performed

Definition at line 58 of file stateful_rng.h.

                                                                             :
            m_entropy_sources(&entropy_sources), m_reseed_interval(reseed_interval) {}

References reseed_interval().

Stateful_RNG() [4/4]

Botan::Stateful_RNG::Stateful_RNG ( )

inline

In this case, automatic reseeding is impossible

Definition at line 64 of file stateful_rng.h.

: m_reseed_interval(0) {}

Member Function Documentation

accepts_input()

bool Botan::Stateful_RNG::accepts_input ( ) const

inlinefinalvirtual

Test whether this RNG accepts externally provided input

Returns

false if this RNG is known to ignore provided inputs

Implements Botan::RandomNumberGenerator.

Definition at line 91 of file stateful_rng.h.

{ return true; }

References accepts_input().

Referenced by accepts_input().

add_entropy() [1/2]

void Botan::RandomNumberGenerator::add_entropy ( const uint8_t input[], size_t length )

inlineinherited

Incorporate some additional data into the RNG state

Parameters

input	a byte array containing the entropy to be added
length	the number of bytes in input

Definition at line 121 of file rng.h.

{ this->add_entropy(std::span(input, length)); }

References add_entropy().

Referenced by add_entropy().

add_entropy() [2/2]

void Botan::RandomNumberGenerator::add_entropy ( std::span< const uint8_t > input )

inlineinherited

Incorporate some additional data into the RNG state. For example adding nonces or timestamps from a peer's protocol message can help hedge against VM state rollback attacks. A few RNG types do not accept any externally provided input, in which case this function is a no-op.

Parameters

input

a byte array containing the entropy to be added

Exceptions

Exception

may throw if the RNG accepts input, but adding the entropy failed.

Definition at line 114 of file rng.h.

{ this->fill_bytes_with_input({}, input); }

References fill_bytes_with_input().

Referenced by add_entropy_T(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::Stateful_RNG::initialize_with(), Botan::Getentropy::poll(), Botan::Intel_Rdseed::poll(), and reseed_from_rng().

add_entropy_T()

template<typename T>

void Botan::RandomNumberGenerator::add_entropy_T ( const T & t )

inlineinherited

Incorporate some additional data into the RNG state.

Definition at line 128 of file rng.h.

                                     {
         this->add_entropy(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
      }

References add_entropy().

Referenced by Botan::Win32_EntropySource::poll().

clear()

void Botan::Stateful_RNG::clear ( )

finalvirtual

Clear all internally held values of this RNG

Implements Botan::RandomNumberGenerator.

Definition at line 15 of file stateful_rng.cpp.

                         {
   const lock_guard_type<recursive_mutex_type> lock(m_mutex);
   m_reseed_counter = 0;
   m_last_pid = 0;
   clear_state();
}

References clear_state(), and Botan::lock().

Referenced by Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), and initialize_with().

clear_state()

virtual void Botan::Stateful_RNG::clear_state ( )

protectedpure virtual

Clear the subclass specific portion of the RNG state

References clear_state(), and Botan::RandomNumberGenerator::RandomNumberGenerator().

Referenced by clear(), and clear_state().

force_reseed()

void Botan::Stateful_RNG::force_reseed

(

)

Mark state as requiring a reseed on next use

Definition at line 22 of file stateful_rng.cpp.

                                {
   const lock_guard_type<recursive_mutex_type> lock(m_mutex);
   m_reseed_counter = 0;
}

References Botan::lock().

generate_output()

virtual void Botan::Stateful_RNG::generate_output ( std::span< uint8_t > output, std::span< const uint8_t > input )

protectedpure virtual

Generate output, incorporating the provided input

Parameters

output	the buffer to fill
input	additional input to incorporate

References generate_output().

Referenced by generate_output().

initialize_with() [1/2]

void Botan::Stateful_RNG::initialize_with ( const uint8_t input[], size_t length )

inline

Consume this input and mark the RNG as initialized regardless of the length of the input or the current seeded state of the RNG.

Parameters

input	the seed material
length	the number of bytes in input

Definition at line 79 of file stateful_rng.h.

{ this->initialize_with(std::span(input, length)); }

References initialize_with().

Referenced by initialize_with().

initialize_with() [2/2]

void Botan::Stateful_RNG::initialize_with

(

std::span< const uint8_t >

input

)

Consume this input and mark the RNG as initialized regardless of the length of the input or the current seeded state of the RNG.

Definition at line 32 of file stateful_rng.cpp.

                                                               {
   const lock_guard_type<recursive_mutex_type> lock(m_mutex);
 
   clear();
   add_entropy(input);
}

References Botan::RandomNumberGenerator::add_entropy(), clear(), and Botan::lock().

is_seeded()

bool Botan::Stateful_RNG::is_seeded ( ) const

finalvirtual

Test whether this RNG has been seeded

Returns

true if this RNG is seeded and ready for use

Implements Botan::RandomNumberGenerator.

Definition at line 27 of file stateful_rng.cpp.

                                   {
   const lock_guard_type<recursive_mutex_type> lock(m_mutex);
   return m_reseed_counter > 0;
}

References Botan::lock().

Referenced by reseed_check().

max_number_of_bytes_per_request()

virtual size_t Botan::Stateful_RNG::max_number_of_bytes_per_request ( ) const

pure virtual

Return the largest number of bytes this DRBG will produce per request 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.

Returns

max number of bytes per request (or zero)

Implemented in Botan::ChaCha_RNG, and Botan::HMAC_DRBG.

name()

virtual std::string Botan::RandomNumberGenerator::name ( ) const

pure virtualinherited

Return the name of this RNG type

Returns

the name of this RNG type

Implemented in Botan::AutoSeeded_RNG, Botan::ChaCha_RNG, Botan::ESDM_RNG, Botan::HMAC_DRBG, Botan::Jitter_RNG, Botan::Null_RNG, Botan::PKCS11::PKCS11_RNG, Botan::Processor_RNG, Botan::System_RNG, Botan::TPM2::RandomNumberGenerator, and Botan::TPM_RNG.

Referenced by Botan::System_RNG::name(), and Botan::Stateful_RNG::reseed_check().

next_byte()

uint8_t Botan::RandomNumberGenerator::next_byte ( )

inlineinherited

Return a random byte

Returns

random byte

Exceptions

PRNG_Unseeded	if the RNG fails because it has not enough entropy
Exception	if the RNG fails

Definition at line 292 of file rng.h.

                          {
         uint8_t b = 0;
         this->fill_bytes_with_input(std::span(&b, 1), {});
         return b;
      }

References fill_bytes_with_input().

Referenced by next_nonzero_byte(), and Botan::random_prime().

next_nonzero_byte()

uint8_t Botan::RandomNumberGenerator::next_nonzero_byte ( )

inlineinherited

Generate a single random byte which is not zero

Returns

a random byte that is greater than zero

Exceptions

PRNG_Unseeded	if the RNG fails because it has not enough entropy
Exception	if the RNG fails

Definition at line 304 of file rng.h.

                                  {
         uint8_t b = this->next_byte();
         while(b == 0) {
            b = this->next_byte();
         }
         return b;
      }

References next_byte().

random_array()

template<size_t bytes>

std::array< uint8_t, bytes > Botan::RandomNumberGenerator::random_array ( )

inlineinherited

Create a std::array of bytes random bytes

Definition at line 280 of file rng.h.

                                              {
         std::array<uint8_t, bytes> result{};
         random_vec(result);
         return result;
      }

References random_vec().

random_vec() [1/3]

template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>

T Botan::RandomNumberGenerator::random_vec ( size_t bytes )

inlineinherited

Create some byte container type and fill it with some random bytes.

Template Parameters

T	the desired byte container type (e.g std::vector<uint8_t>)

Parameters

bytes

number of random bytes to initialize the container with

Returns

a container of type T with bytes random bytes

Exceptions

Exception

if RNG or memory allocation fails

Definition at line 270 of file rng.h.

                                 {
         T result;
         random_vec(result, bytes);
         return result;
      }

References random_vec().

random_vec() [2/3]

void Botan::RandomNumberGenerator::random_vec ( std::span< uint8_t > v )

inlineinherited

Fill a given byte container with bytes random bytes

Todo

deprecate this overload (in favor of randomize())

Parameters

v	the container to be filled with bytes random bytes

Exceptions

Exception

if RNG fails

Definition at line 244 of file rng.h.

{ this->randomize(v); }

References randomize().

Referenced by Botan::Classic_McEliece_PrivateKey::Classic_McEliece_PrivateKey(), Botan::TLS::Client_Key_Exchange::Client_Key_Exchange(), Botan::TLS::Client_Key_Exchange::Client_Key_Exchange(), Botan::PK_Decryptor::decrypt_or_random(), Botan::Dilithium_PrivateKey::Dilithium_PrivateKey(), Botan::Ed25519_PrivateKey::Ed25519_PrivateKey(), Botan::Kyber_KEM_Encryptor::encapsulate(), Botan::ML_KEM_Encryptor::encapsulate(), Botan::TLS::Session::encrypt(), Botan::KeyPair::encryption_consistency_check(), Botan::FrodoKEM_PrivateKey::FrodoKEM_PrivateKey(), Botan::generate_bcrypt(), Botan::Kyber_PrivateKey::Kyber_PrivateKey(), Botan::TLS::make_hello_random(), Botan::OctetString::OctetString(), random_array(), random_vec(), random_vec(), Botan::BigInt::randomize(), reseed_from_rng(), Botan::SphincsPlus_PrivateKey::SphincsPlus_PrivateKey(), Botan::X25519_PrivateKey::X25519_PrivateKey(), and Botan::XMSS_PublicKey::XMSS_PublicKey().

random_vec() [3/3]

template<concepts::resizable_byte_buffer T>

void Botan::RandomNumberGenerator::random_vec ( T & v, size_t bytes )

inlineinherited

Resize a given byte container to bytes and fill it with random bytes

Template Parameters

T	the desired byte container type (e.g std::vector<uint8_t>)

Parameters

v	the container to be filled with bytes random bytes
bytes	number of random bytes to initialize the container with

Exceptions

Exception

if RNG or memory allocation fails

Definition at line 255 of file rng.h.

                                          {
         v.resize(bytes);
         random_vec(v);
      }

References random_vec().

randomize() [1/2]

void Botan::RandomNumberGenerator::randomize ( std::span< uint8_t > output )

inlineinherited

Randomize a byte array.

May block shortly if e.g. the RNG is not yet initialized or a retry because of insufficient entropy is needed.

Parameters

output

the byte array to hold the random output.

Exceptions

PRNG_Unseeded	if the RNG fails because it has not enough entropy
Exception	if the RNG fails

Definition at line 86 of file rng.h.

{ this->fill_bytes_with_input(output, {}); }

References fill_bytes_with_input().

Referenced by Botan::TLS::Connection_Cipher_State::aead_nonce(), Botan::argon2_generate_pwhash(), Botan::BlindedScalarBits< C, WindowBits+1 >::BlindedScalarBits(), botan_system_rng_get(), Botan::CryptoBox::encrypt(), Botan::PKCS12::export_to(), Botan::generate_dsa_primes(), Botan::generate_passhash9(), Botan::pkcs12_pbe_encrypt(), Botan::IntMod< MontgomeryRep< ScalarParams > >::random(), Botan::X509_Serial_Number::random(), Botan::random_gf2m(), Botan::McEliece_PublicKeyInternal::random_plaintext_element(), Botan::random_prime(), random_vec(), Botan::Sodium::randombytes_buf(), randomize_with_ts_input(), Botan::KeyPair::signature_consistency_check(), Botan::RTSS_Share::split(), and Botan::UUID::UUID().

randomize() [2/2]

void Botan::RandomNumberGenerator::randomize ( uint8_t output[], size_t length )

inlineinherited

Randomize a byte array

Parameters

output	the byte array to hold the random output
length	the number of bytes to generate

Definition at line 93 of file rng.h.

{ this->randomize(std::span(output, length)); }

References randomize().

Referenced by randomize().

randomize_with_input() [1/2]

void Botan::RandomNumberGenerator::randomize_with_input ( std::span< uint8_t > output, std::span< const uint8_t > input )

inlineinherited

Incorporate entropy into the RNG state then produce output. Some RNG types implement this using a single operation, default calls add_entropy + randomize in sequence.

Use this to further bind the outputs to your current process/protocol state. For instance if generating a new key for use in a session, include a session ID or other such value. See NIST SP 800-90 A, B, C series for more ideas.

Parameters

output	buffer to hold the random output
input	entropy buffer to incorporate

Exceptions

PRNG_Unseeded	if the RNG fails because it has not enough entropy
Exception	if the RNG fails
Exception	may throw if the RNG accepts input, but adding the entropy failed.

Definition at line 148 of file rng.h.

                                                                                       {
         this->fill_bytes_with_input(output, input);
      }

References fill_bytes_with_input().

Referenced by Botan::System_RNG::fill_bytes_with_input(), and randomize_with_input().

randomize_with_input() [2/2]

void Botan::RandomNumberGenerator::randomize_with_input ( uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len )

inlineinherited

Randomize a byte array, first incorporating additional input

Parameters

output	the byte array to hold the random output
output_len	the number of bytes to generate
input	a byte array containing the entropy to be added
input_len	the number of bytes in input

Definition at line 159 of file rng.h.

                                                                                                              {
         this->randomize_with_input(std::span(output, output_len), std::span(input, input_len));
      }

References randomize_with_input().

randomize_with_ts_input() [1/2]

void Botan::RandomNumberGenerator::randomize_with_ts_input ( std::span< uint8_t > output )

inherited

This calls randomize_with_input using system specific values

This first attempts to provide input to the underlying RNG from some system specific source. If a system RNG is available, it is queried and the output from the system RNG is used as the additional input. Otherwise 12 bytes consisting of the local clock plus the current process ID are used.

For a stateful RNG that was already correctly seeded with sufficient cryptographically secure material, using non-random but potentially unique data as the extra input can help protect against problems with fork, VM state rollback, or other cases where somehow an RNG state is duplicated. If both of the duplicated RNG states later incorporate some input, even predictable input, their outputs will diverge.

Parameters

output

buffer to hold the random output

Exceptions

PRNG_Unseeded	if the RNG fails because it has not enough entropy
Exception	if the RNG fails
Exception	may throw if the RNG accepts input, but adding the entropy failed.

Definition at line 26 of file rng.cpp.

                                                                           {
   if(this->accepts_input()) {
      std::array<uint8_t, 16> additional_input = {0};
 
#if defined(BOTAN_HAS_SYSTEM_RNG)
      // If we have a system RNG just read 128 bits from that
      system_rng().randomize(additional_input);
      constexpr size_t written = additional_input.size();
#elif defined(BOTAN_HAS_OS_UTILS)
      // Otherwise take clock + pid
      const uint64_t clock = OS::get_high_resolution_clock();
      const uint32_t pid = OS::get_process_id();  // 0 if no PIDs on this system
 
      store_le(std::span{additional_input}.first<8>(), clock);
      store_le(std::span{additional_input}.subspan<8, 4>(), pid);
      const size_t written = 8 + (pid != 0) ? 4 : 0;
#else
      // Nothing to use in this case
      constexpr size_t written = 0;
#endif
 
      this->fill_bytes_with_input(output, std::span{additional_input}.first(written));
   } else {
      this->fill_bytes_with_input(output, {});
   }
}

References accepts_input(), fill_bytes_with_input(), Botan::OS::get_high_resolution_clock(), Botan::OS::get_process_id(), randomize(), Botan::store_le(), and Botan::system_rng().

Referenced by randomize_with_ts_input().

randomize_with_ts_input() [2/2]

void Botan::RandomNumberGenerator::randomize_with_ts_input ( uint8_t output[], size_t output_len )

inlineinherited

Randomize a byte array, using timestamps as additional input

Parameters

output	the byte array to hold the random output
output_len	the number of bytes to generate

Definition at line 190 of file rng.h.

                                                                        {
         this->randomize_with_ts_input(std::span(output, output_len));
      }

References randomize_with_ts_input().

reseed()

size_t Botan::RandomNumberGenerator::reseed ( Entropy_Sources & srcs, size_t poll_bits = RandomNumberGenerator::DefaultPollBits, std::chrono::milliseconds = DefaultPollTimeout )

inlineinherited

Poll provided sources for up to poll_bits bits of entropy. Returns estimate of the number of bits collected.

Sets the seeded state to true if enough entropy was added.

TODO(Botan4) remove this function

Definition at line 337 of file rng.h.

                                                                       {
         return reseed_from(srcs, poll_bits);
      }

References DefaultPollBits, DefaultPollTimeout, RandomNumberGenerator(), reseed(), and reseed_from().

Referenced by reseed().

reseed_check()

void Botan::Stateful_RNG::reseed_check ( )

protected

Reseed if the reseed interval has elapsed, or throw if unseeded

Definition at line 106 of file stateful_rng.cpp.

                                {
   // Lock is held whenever this function is called
 
   const uint32_t cur_pid = OS::get_process_id();
 
   const bool fork_detected = (m_last_pid > 0) && (cur_pid != m_last_pid);
 
   if(is_seeded() == false || fork_detected || (m_reseed_interval > 0 && m_reseed_counter >= m_reseed_interval)) {
      m_reseed_counter = 0;
      m_last_pid = cur_pid;
 
      if(m_underlying_rng != nullptr) {
         reseed_from_rng(*m_underlying_rng, security_level());
      }
 
      if(m_entropy_sources != nullptr) {
         reseed_from_sources(*m_entropy_sources, security_level());
      }
 
      if(!is_seeded()) {
         if(fork_detected) {
            throw Invalid_State("Detected use of fork but cannot reseed DRBG");
         } else {
            throw PRNG_Unseeded(name());
         }
      }
   } else {
      BOTAN_ASSERT(m_reseed_counter != 0, "RNG is seeded");
      m_reseed_counter += 1;
   }
}

References BOTAN_ASSERT, Botan::OS::get_process_id(), is_seeded(), Botan::RandomNumberGenerator::name(), reseed_from_rng(), reseed_from_sources(), and security_level().

reseed_from() [1/2]

size_t Botan::RandomNumberGenerator::reseed_from ( Entropy_Sources & srcs, size_t poll_bits = RandomNumberGenerator::DefaultPollBits )

inlineinherited

Poll provided sources for up to poll_bits bits of entropy. Returns estimate of the number of bits collected. Sets the seeded state to true if enough entropy was added.

Exceptions

Exception

if RNG accepts input but reseeding failed.

Definition at line 219 of file rng.h.

                                                                                                       {
         return reseed_from_sources(srcs, poll_bits);
      }

References DefaultPollBits, and reseed_from_sources().

Referenced by reseed().

reseed_from() [2/2]

void Botan::RandomNumberGenerator::reseed_from ( RandomNumberGenerator & rng, size_t poll_bits = RandomNumberGenerator::DefaultPollBits )

inlineinherited

Reseed by reading specified bits from the RNG

Sets the seeded state to true if enough entropy was added.

Exceptions

Exception

if RNG accepts input but reseeding failed.

Definition at line 230 of file rng.h.

                                                                                                          {
         return reseed_from_rng(rng, poll_bits);
      }

References DefaultPollBits, RandomNumberGenerator(), and reseed_from_rng().

reseed_from_rng()

void Botan::Stateful_RNG::reseed_from_rng ( RandomNumberGenerator & rng, size_t poll_bits = RandomNumberGenerator::DefaultPollBits )

finalvirtual

Reseed this RNG from another RNG

Parameters

Random Number Generators	the RNG to draw seed material from
poll_bits	the number of bits to collect

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 90 of file stateful_rng.cpp.

                                                                               {
   const lock_guard_type<recursive_mutex_type> lock(m_mutex);
 
   RandomNumberGenerator::reseed_from_rng(rng, poll_bits);
 
   if(poll_bits >= security_level()) {
      reset_reseed_counter();
   }
}

References Botan::lock(), Botan::RandomNumberGenerator::RandomNumberGenerator(), Botan::RandomNumberGenerator::reseed_from_rng(), and security_level().

Referenced by reseed_check().

reseed_from_sources()

size_t Botan::Stateful_RNG::reseed_from_sources ( Entropy_Sources & srcs, size_t poll_bits = RandomNumberGenerator::DefaultPollBits )

finalvirtual

Poll provided sources for up to poll_bits bits of entropy. Returns estimate of the number of bits collected.

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 78 of file stateful_rng.cpp.

                                                                                {
   const lock_guard_type<recursive_mutex_type> lock(m_mutex);
 
   const size_t bits_collected = RandomNumberGenerator::reseed_from_sources(srcs, poll_bits);
 
   if(bits_collected >= security_level()) {
      reset_reseed_counter();
   }
 
   return bits_collected;
}

References Botan::lock(), Botan::RandomNumberGenerator::reseed_from_sources(), and security_level().

Referenced by reseed_check().

reseed_interval()

size_t Botan::Stateful_RNG::reseed_interval ( ) const

inline

Return how many requests may be made before automatic reseeding

Returns

the reseed interval, or zero if automatic reseeding is disabled

Definition at line 135 of file stateful_rng.h.

{ return m_reseed_interval; }

Referenced by Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Stateful_RNG(), Stateful_RNG(), and Stateful_RNG().

security_level()

virtual size_t Botan::Stateful_RNG::security_level ( ) const

pure virtual

Return the security level of this DRBG

Returns

intended security level of this DRBG

Implemented in Botan::ChaCha_RNG, and Botan::HMAC_DRBG.

Referenced by reseed_check(), reseed_from_rng(), and reseed_from_sources().

update()

virtual void Botan::Stateful_RNG::update ( std::span< const uint8_t > input )

protectedpure virtual

Incorporate the provided input into the RNG state

Parameters

input

the seed material

References update().

Referenced by update().

Member Data Documentation

DefaultPollBits

size_t Botan::RandomNumberGenerator::DefaultPollBits = 256

staticconstexprinherited

Number of entropy bits polled for reseeding userspace RNGs like HMAC_DRBG

Definition at line 50 of file rng.h.

Referenced by reseed(), reseed_from(), and reseed_from().

DefaultPollTimeout

auto Botan::RandomNumberGenerator::DefaultPollTimeout = std::chrono::milliseconds(50)

staticconstexprinherited

Default poll timeout

Definition at line 326 of file rng.h.

Referenced by reseed().

DefaultReseedInterval

size_t Botan::RandomNumberGenerator::DefaultReseedInterval = 1024

staticconstexprinherited

Userspace RNGs like HMAC_DRBG will reseed after a specified number of outputs are generated. Set to zero to disable automatic reseeding.

Definition at line 45 of file rng.h.

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The documentation for this class was generated from the following files:

• src/lib/rng/stateful_rng/stateful_rng.h
• src/lib/rng/stateful_rng/stateful_rng.cpp