Botan::ChaCha_RNG Class Reference

#include <chacha_rng.h>

Inheritance diagram for Botan::ChaCha_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)
	ChaCha_RNG ()
BOTAN_FUTURE_EXPLICIT	ChaCha_RNG (Entropy_Sources &entropy_sources, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval)
	ChaCha_RNG (RandomNumberGenerator &underlying_rng, Entropy_Sources &entropy_sources, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval)
BOTAN_FUTURE_EXPLICIT	ChaCha_RNG (RandomNumberGenerator &underlying_rng, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval)
BOTAN_FUTURE_EXPLICIT	ChaCha_RNG (std::span< const uint8_t > seed)
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
size_t	max_number_of_bytes_per_request () const override
std::string	name () const override
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
size_t	security_level () const 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

ChaCha_RNG is a very fast but completely ad-hoc RNG created by creating a 256-bit random value and using it as a key for ChaCha20.

The RNG maintains two 256-bit keys, one for HMAC_SHA256 (HK) and the other for ChaCha20 (CK). To compute a new key in response to reseeding request or add_entropy calls, ChaCha_RNG computes CK' = HMAC_SHA256(HK, input_material) Then a new HK' is computed by running ChaCha20 with the new key to output 32 bytes: HK' = ChaCha20(CK')

Now output can be produced by continuing to produce output with ChaCha20 under CK'

The first HK (before seeding occurs) is taken as the all zero value.

Warning

This RNG construction is probably fine but is non-standard. The primary reason to use it is in cases where the other RNGs are not fast enough.

Definition at line 40 of file chacha_rng.h.

Constructor & Destructor Documentation

ChaCha_RNG() [1/5]

Botan::ChaCha_RNG::ChaCha_RNG

(

)

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 14 of file chacha_rng.cpp.

                       {
   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
   clear();
}

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), and Botan::StreamCipher::create_or_throw().

ChaCha_RNG() [2/5]

Botan::ChaCha_RNG::ChaCha_RNG

(

std::span< const uint8_t >

seed

)

Provide an initial seed to the RNG, without providing an underlying RNG or entropy source. 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.

Parameters

SEED	the seed material, should be at least 256 bits

Definition at line 20 of file chacha_rng.cpp.

                                                  {
   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
   clear();
   add_entropy(seed);
}

References Botan::RandomNumberGenerator::add_entropy(), Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), and Botan::StreamCipher::create_or_throw().

ChaCha_RNG() [3/5]

Botan::ChaCha_RNG::ChaCha_RNG	(	RandomNumberGenerator &	underlying_rng,
		size_t	reseed_interval = RandomNumberGenerator::DefaultReseedInterval )

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

Parameters

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

Definition at line 27 of file chacha_rng.cpp.

                                                                                    :
      Stateful_RNG(underlying_rng, reseed_interval) {
   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
   clear();
}

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), Botan::StreamCipher::create_or_throw(), Botan::Stateful_RNG::reseed_interval(), and Botan::Stateful_RNG::Stateful_RNG().

ChaCha_RNG() [4/5]

Botan::ChaCha_RNG::ChaCha_RNG	(	Entropy_Sources &	entropy_sources,
		size_t	reseed_interval = RandomNumberGenerator::DefaultReseedInterval )

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

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 43 of file chacha_rng.cpp.

                                                                               :
      Stateful_RNG(entropy_sources, reseed_interval) {
   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
   clear();
}

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), Botan::StreamCipher::create_or_throw(), Botan::Stateful_RNG::reseed_interval(), and Botan::Stateful_RNG::Stateful_RNG().

ChaCha_RNG() [5/5]

Botan::ChaCha_RNG::ChaCha_RNG	(	RandomNumberGenerator &	underlying_rng,
		Entropy_Sources &	entropy_sources,
		size_t	reseed_interval = RandomNumberGenerator::DefaultReseedInterval )

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

Parameters

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.

Definition at line 34 of file chacha_rng.cpp.

                                               :
      Stateful_RNG(underlying_rng, entropy_sources, reseed_interval) {
   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
   m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
   clear();
}

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), Botan::StreamCipher::create_or_throw(), Botan::Stateful_RNG::reseed_interval(), and Botan::Stateful_RNG::Stateful_RNG().

Member Function Documentation

accepts_input()

bool Botan::Stateful_RNG::accepts_input ( ) const

inlinefinalvirtualinherited

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 ( )

finalvirtualinherited

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().

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

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 )

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

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()

size_t Botan::ChaCha_RNG::max_number_of_bytes_per_request ( ) const

inlineoverridevirtual

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

Returns

always zero, as this RNG has no such limit

Implements Botan::Stateful_RNG.

Definition at line 120 of file chacha_rng.h.

{ return 0; }

name()

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

inlineoverridevirtual

Return the name of this RNG type

Returns

the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 108 of file chacha_rng.h.

{ return "ChaCha_RNG"; }

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 ( )

protectedinherited

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 )

finalvirtualinherited

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 )

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

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()

size_t Botan::ChaCha_RNG::security_level ( ) const

overridevirtual

Return the security level of this DRBG

Returns

the estimated security level in bits

Implements Botan::Stateful_RNG.

Definition at line 72 of file chacha_rng.cpp.

                                        {
   return 256;
}

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.

---

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

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