Botan::HMAC_DRBG Class Reference

#include <hmac_drbg.h>

Inheritance diagram for Botan::HMAC_DRBG:

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> requires std::is_standard_layout_v<T> && std::is_trivial_v<T>
void	add_entropy_T (const T &t)
void	clear () final
void	force_reseed ()
	HMAC_DRBG (const HMAC_DRBG &rng)=delete
	HMAC_DRBG (HMAC_DRBG &&rng)=delete
	HMAC_DRBG (std::string_view hmac_hash)
	HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf)
	HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf, Entropy_Sources &entropy_sources, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval, size_t max_number_of_bytes_per_request=64 *1024)
	HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf, RandomNumberGenerator &underlying_rng, Entropy_Sources &entropy_sources, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval, size_t max_number_of_bytes_per_request=64 *1024)
	HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf, RandomNumberGenerator &underlying_rng, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval, size_t max_number_of_bytes_per_request=64 *1024)
void	initialize_with (const uint8_t input[], size_t length)
void	initialize_with (std::span< const uint8_t > input)
bool	is_seeded () const final
size_t	max_number_of_bytes_per_request () const override
std::string	name () const override
uint8_t	next_byte ()
uint8_t	next_nonzero_byte ()
HMAC_DRBG &	operator= (const HMAC_DRBG &rng)=delete
HMAC_DRBG &	operator= (HMAC_DRBG &&rng)=delete
template<size_t bytes>
std::array< uint8_t, bytes >	random_array ()
template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>> requires std::default_initializable<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
size_t	security_level () const override
	~HMAC_DRBG () override

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
void	reseed_check ()

Detailed Description

HMAC_DRBG from NIST SP800-90A

Definition at line 22 of file hmac_drbg.h.

Constructor & Destructor Documentation

HMAC_DRBG() [1/7]

Botan::HMAC_DRBG::HMAC_DRBG ( std::unique_ptr< MessageAuthenticationCode > prf )

explicit

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

Automatic reseeding is disabled completely, as it has no access to any source for seed material.

If a fork is detected, the RNG will be unable to reseed itself in response. In this case, an exception will be thrown rather than generating duplicated output.

Definition at line 97 of file hmac_drbg.cpp.

                                                                 :
      m_mac(std::move(prf)),
      m_max_number_of_bytes_per_request(64 * 1024),
      m_security_level(hmac_drbg_security_level(m_mac->output_length())) {
   BOTAN_ASSERT_NONNULL(m_mac);
   clear();
}

References BOTAN_ASSERT_NONNULL, and Botan::Stateful_RNG::clear().

Referenced by HMAC_DRBG(), HMAC_DRBG(), operator=(), and operator=().

HMAC_DRBG() [2/7]

Botan::HMAC_DRBG::HMAC_DRBG ( std::string_view hmac_hash )

explicit

Constructor taking a string for the hash

Definition at line 105 of file hmac_drbg.cpp.

                                             :
      m_mac(MessageAuthenticationCode::create_or_throw(fmt("HMAC({})", hmac_hash))),
      m_max_number_of_bytes_per_request(64 * 1024),
      m_security_level(hmac_drbg_security_level(m_mac->output_length())) {
   clear();
}

References Botan::Stateful_RNG::clear(), and Botan::fmt().

HMAC_DRBG() [3/7]

Botan::HMAC_DRBG::HMAC_DRBG	(	std::unique_ptr< MessageAuthenticationCode >	prf,
		RandomNumberGenerator &	underlying_rng,
		size_t	reseed_interval = RandomNumberGenerator::DefaultReseedInterval,
		size_t	max_number_of_bytes_per_request = 64 * 1024 )

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

Automatic reseeding from underlying_rng will take place after reseed_interval many requests or after a fork was detected.

Parameters

prf	MAC to use as a PRF
underlying_rng	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 (max. 2^24)
max_number_of_bytes_per_request	requests that are in size higher than max_number_of_bytes_per_request are treated as if multiple single requests of max_number_of_bytes_per_request size had been made. In theory SP 800-90A requires that we reject any request for a DRBG output longer than max_number_of_bytes_per_request. To avoid inconveniencing the caller who wants an output larger than max_number_of_bytes_per_request, instead treat these requests as if multiple requests of max_number_of_bytes_per_request size had been made. NIST requires for HMAC_DRBG that every implementation set a value no more than 2**19 bits (or 64 KiB). Together with reseed_interval = 1 you can enforce that for example every 512 bit automatic reseeding occurs.

Definition at line 51 of file hmac_drbg.cpp.

                                                             :
      Stateful_RNG(underlying_rng, reseed_interval),
      m_mac(std::move(prf)),
      m_max_number_of_bytes_per_request(max_number_of_bytes_per_request),
      m_security_level(hmac_drbg_security_level(m_mac->output_length())) {
   BOTAN_ASSERT_NONNULL(m_mac);
 
   check_limits(reseed_interval, max_number_of_bytes_per_request);
 
   clear();
}

References BOTAN_ASSERT_NONNULL, Botan::Stateful_RNG::clear(), max_number_of_bytes_per_request(), Botan::Stateful_RNG::reseed_interval(), and Botan::Stateful_RNG::Stateful_RNG().

HMAC_DRBG() [4/7]

Botan::HMAC_DRBG::HMAC_DRBG	(	std::unique_ptr< MessageAuthenticationCode >	prf,
		Entropy_Sources &	entropy_sources,
		size_t	reseed_interval = RandomNumberGenerator::DefaultReseedInterval,
		size_t	max_number_of_bytes_per_request = 64 * 1024 )

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

Automatic reseeding from entropy_sources will take place after reseed_interval many requests or after a fork was detected.

Parameters

prf	MAC to use as a PRF
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 (max. 2^24)
max_number_of_bytes_per_request	requests that are in size higher than max_number_of_bytes_per_request are treated as if multiple single requests of max_number_of_bytes_per_request size had been made. In theory SP 800-90A requires that we reject any request for a DRBG output longer than max_number_of_bytes_per_request. To avoid inconveniencing the caller who wants an output larger than max_number_of_bytes_per_request, instead treat these requests as if multiple requests of max_number_of_bytes_per_request size had been made. NIST requires for HMAC_DRBG that every implementation set a value no more than 2**19 bits (or 64 KiB). Together with reseed_interval = 1 you can enforce that for example every 512 bit automatic reseeding occurs.

Definition at line 82 of file hmac_drbg.cpp.

                                                             :
      Stateful_RNG(entropy_sources, reseed_interval),
      m_mac(std::move(prf)),
      m_max_number_of_bytes_per_request(max_number_of_bytes_per_request),
      m_security_level(hmac_drbg_security_level(m_mac->output_length())) {
   BOTAN_ASSERT_NONNULL(m_mac);
 
   check_limits(reseed_interval, max_number_of_bytes_per_request);
 
   clear();
}

References BOTAN_ASSERT_NONNULL, Botan::Stateful_RNG::clear(), max_number_of_bytes_per_request(), Botan::Stateful_RNG::reseed_interval(), and Botan::Stateful_RNG::Stateful_RNG().

HMAC_DRBG() [5/7]

Botan::HMAC_DRBG::HMAC_DRBG	(	std::unique_ptr< MessageAuthenticationCode >	prf,
		RandomNumberGenerator &	underlying_rng,
		Entropy_Sources &	entropy_sources,
		size_t	reseed_interval = RandomNumberGenerator::DefaultReseedInterval,
		size_t	max_number_of_bytes_per_request = 64 * 1024 )

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

Automatic reseeding from underlying_rng and entropy_sources will take place after reseed_interval many requests or after a fork was detected.

Parameters

prf	MAC to use as a PRF
underlying_rng	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 (max. 2^24)
max_number_of_bytes_per_request	requests that are in size higher than max_number_of_bytes_per_request are treated as if multiple single requests of max_number_of_bytes_per_request size had been made. In theory SP 800-90A requires that we reject any request for a DRBG output longer than max_number_of_bytes_per_request. To avoid inconveniencing the caller who wants an output larger than max_number_of_bytes_per_request, instead treat these requests as if multiple requests of max_number_of_bytes_per_request size had been made. NIST requires for HMAC_DRBG that every implementation set a value no more than 2**19 bits (or 64 KiB). Together with reseed_interval = 1 you can enforce that for example every 512 bit automatic reseeding occurs.

Definition at line 66 of file hmac_drbg.cpp.

                                                             :
      Stateful_RNG(underlying_rng, entropy_sources, reseed_interval),
      m_mac(std::move(prf)),
      m_max_number_of_bytes_per_request(max_number_of_bytes_per_request),
      m_security_level(hmac_drbg_security_level(m_mac->output_length())) {
   BOTAN_ASSERT_NONNULL(m_mac);
 
   check_limits(reseed_interval, max_number_of_bytes_per_request);
 
   clear();
}

References BOTAN_ASSERT_NONNULL, Botan::Stateful_RNG::clear(), max_number_of_bytes_per_request(), Botan::Stateful_RNG::reseed_interval(), and Botan::Stateful_RNG::Stateful_RNG().

~HMAC_DRBG()

Botan::HMAC_DRBG::~HMAC_DRBG ( )

overridedefault

HMAC_DRBG() [6/7]

Botan::HMAC_DRBG::HMAC_DRBG ( const HMAC_DRBG & rng )

delete

References HMAC_DRBG().

HMAC_DRBG() [7/7]

Botan::HMAC_DRBG::HMAC_DRBG ( HMAC_DRBG && rng )

delete

References HMAC_DRBG().

Member Function Documentation

accepts_input()

bool Botan::Stateful_RNG::accepts_input ( ) const

inlinefinalvirtualinherited

Returns false if it is known that this RNG object is not able to accept externally provided inputs (via add_entropy, randomize_with_input, etc). In this case, any such provided inputs are ignored.

If this function returns true, then inputs may or may not be accepted.

Implements Botan::RandomNumberGenerator.

Definition at line 71 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

Definition at line 100 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 98 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>
requires std::is_standard_layout_v<T> && std::is_trivial_v<T>

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

inlineinherited

Incorporate some additional data into the RNG state.

Definition at line 107 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 ( )

finalvirtualinherited

Clear all internally held values of this RNG

Postcondition

is_seeded() == false if the RNG has an internal state that can be cleared.

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().

force_reseed()

void Botan::Stateful_RNG::force_reseed ( )

inherited

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().

initialize_with() [1/2]

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

inlineinherited

Definition at line 67 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 )

inherited

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

finalvirtualinherited

Check whether this RNG is seeded.

Returns

true if this RNG was already seeded, false otherwise.

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()

size_t Botan::HMAC_DRBG::max_number_of_bytes_per_request ( ) const

inlineoverridevirtual

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)

Implements Botan::Stateful_RNG.

Definition at line 139 of file hmac_drbg.h.

{ return m_max_number_of_bytes_per_request; }

Referenced by HMAC_DRBG(), HMAC_DRBG(), and HMAC_DRBG().

name()

std::string Botan::HMAC_DRBG::name ( ) const

overridevirtual

Returns

the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 123 of file hmac_drbg.cpp.

                                {
   return fmt("HMAC_DRBG({})", m_mac->name());
}

References Botan::fmt().

Referenced by operator=().

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 252 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

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 263 of file rng.h.

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

References next_byte().

operator=() [1/2]

HMAC_DRBG & Botan::HMAC_DRBG::operator= ( const HMAC_DRBG & rng )

delete

References HMAC_DRBG().

operator=() [2/2]

HMAC_DRBG & Botan::HMAC_DRBG::operator= ( HMAC_DRBG && rng )

delete

References HMAC_DRBG(), name(), and security_level().

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 240 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>>
requires std::default_initializable<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 230 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 204 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(), and Botan::X25519_PrivateKey::X25519_PrivateKey().

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 215 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 75 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::generate_dsa_primes(), Botan::generate_passhash9(), Botan::IntMod< MontgomeryRep< ScalarParams > >::random(), Botan::random_gf2m(), Botan::McEliece_PublicKey::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

Definition at line 77 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 127 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

Definition at line 131 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 some timestamps as extra input.

For a stateful RNG using non-random but potentially unique data 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 a timestamp (and the timestamps don't themselves repeat), 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 28 of file rng.cpp.

                                                                           {
   if(this->accepts_input()) {
      std::array<uint8_t, 32> additional_input = {0};
 
#if defined(BOTAN_HAS_OS_UTILS)
      store_le(std::span{additional_input}.subspan<0, 8>(), OS::get_high_resolution_clock());
      store_le(std::span{additional_input}.subspan<8, 4>(), OS::get_process_id());
      constexpr size_t offset = 12;
#else
      constexpr size_t offset = 0;
#endif
 
#if defined(BOTAN_HAS_SYSTEM_RNG)
      system_rng().randomize(std::span{additional_input}.subspan<offset>());
#else
      BOTAN_UNUSED(offset);
#endif
 
      this->fill_bytes_with_input(output, additional_input);
   } else {
      this->fill_bytes_with_input(output, {});
   }
}

References accepts_input(), BOTAN_UNUSED, 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

Definition at line 151 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 296 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 ( )

protectedinherited

Definition at line 105 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 179 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 190 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 )

finalvirtualinherited

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.

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 )

finalvirtualinherited

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

inlineinherited

Definition at line 104 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()

size_t Botan::HMAC_DRBG::security_level ( ) const

overridevirtual

Returns

intended security level of this DRBG

Implements Botan::Stateful_RNG.

Definition at line 178 of file hmac_drbg.cpp.

                                       {
   return m_security_level;
}

Referenced by operator=().

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 285 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.

---

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

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