Botan::Null_RNG Class Reference

#include <rng.h>

Inheritance diagram for Botan::Null_RNG:

Public Member Functions
bool	accepts_input () const override
void	add_entropy (const uint8_t[], size_t) override
template<typename T >
void	add_entropy_T (const T &t)
void	clear () override
bool	is_seeded () const override
std::string	name () const override
uint8_t	next_byte ()
uint8_t	next_nonzero_byte ()
secure_vector< uint8_t >	random_vec (size_t bytes)
void	randomize (uint8_t[], size_t) override
virtual void	randomize_with_input (uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)
virtual void	randomize_with_ts_input (uint8_t output[], size_t output_len)
virtual size_t	reseed (Entropy_Sources &srcs, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS, std::chrono::milliseconds poll_timeout=BOTAN_RNG_RESEED_DEFAULT_TIMEOUT)
virtual void	reseed_from_rng (RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS)

Static Public Member Functions
static RandomNumberGenerator *	make_rng ()

Detailed Description

Null/stub RNG - fails if you try to use it for anything This is not generally useful except for in certain tests

Definition at line 197 of file rng.h.

Member Function Documentation

accepts_input()

bool Botan::Null_RNG::accepts_input ( ) const

inlineoverridevirtual

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 202 of file rng.h.

{ return false; }

add_entropy()

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

inlineoverridevirtual

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 containg the entropy to be added
length	the length of the byte array in

Implements Botan::RandomNumberGenerator.

Definition at line 211 of file rng.h.

{}

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 68 of file rng.h.

References T.

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

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

clear()

void Botan::Null_RNG::clear ( )

inlineoverridevirtual

Clear all internally held values of this RNG

Postcondition

is_seeded() == false

Implements Botan::RandomNumberGenerator.

Definition at line 204 of file rng.h.

{}

is_seeded()

bool Botan::Null_RNG::is_seeded ( ) const

inlineoverridevirtual

Check whether this RNG is seeded.

Returns

true if this RNG was already seeded, false otherwise.

Implements Botan::RandomNumberGenerator.

Definition at line 200 of file rng.h.

{ return false; }

make_rng()

RandomNumberGenerator * Botan::RandomNumberGenerator::make_rng ( )

staticinherited

Create a seeded and active RNG object for general application use Added in 1.8.0 Use AutoSeeded_RNG instead

Definition at line 69 of file rng.cpp.

   {
#if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
   return new AutoSeeded_RNG;
#else
   throw Exception("make_rng failed, no AutoSeeded_RNG in this build");
#endif
   }

name()

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

inlineoverridevirtual

Returns

the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 213 of file rng.h.

{ return "Null_RNG"; }

next_byte()

uint8_t Botan::RandomNumberGenerator::next_byte ( )

inlineinherited

Return a random byte

Returns

random byte

Definition at line 152 of file rng.h.

Referenced by Botan::random_prime().

         {
         uint8_t b;
         this->randomize(&b, 1);
         return b;
         }

next_nonzero_byte()

uint8_t Botan::RandomNumberGenerator::next_nonzero_byte ( )

inlineinherited

Returns

a random byte that is greater than zero

Definition at line 162 of file rng.h.

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

random_vec()

secure_vector<uint8_t> Botan::RandomNumberGenerator::random_vec ( size_t  bytes )

inlineinherited

Return a random vector

Parameters

bytes

number of bytes in the result

Returns

randomized vector of length bytes

Definition at line 141 of file rng.h.

Referenced by Botan::CECPQ1_accept(), Botan::CECPQ1_offer(), Botan::TLS::Client_Key_Exchange::Client_Key_Exchange(), Botan::Curve25519_PrivateKey::Curve25519_PrivateKey(), Botan::PK_Decryptor::decrypt_or_random(), Botan::Ed25519_PrivateKey::Ed25519_PrivateKey(), Botan::TLS::Session::encrypt(), Botan::KeyPair::encryption_consistency_check(), Botan::generate_bcrypt(), Botan::mceies_encrypt(), Botan::OctetString::OctetString(), Botan::BigInt::randomize(), and Botan::TLS::Session_Manager_In_Memory::remove_all().

         {
         secure_vector<uint8_t> output(bytes);
         this->randomize(output.data(), output.size());
         return output;
         }

randomize()

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

inlineoverridevirtual

Randomize a byte array.

Parameters

output	the byte array to hold the random output.
length	the length of the byte array output in bytes.

Implements Botan::RandomNumberGenerator.

Definition at line 206 of file rng.h.

         {
         throw PRNG_Unseeded("Null_RNG called");
         }

randomize_with_input()

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

virtualinherited

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
output_len	size of the output buffer in bytes
input	entropy buffer to incorporate
input_len	size of the input buffer in bytes

Reimplemented in Botan::HMAC_DRBG, Botan::ChaCha_RNG, and Botan::AutoSeeded_RNG.

Definition at line 38 of file rng.cpp.

References Botan::RandomNumberGenerator::add_entropy(), and Botan::RandomNumberGenerator::randomize().

Referenced by Botan::Stateful_RNG::randomize_with_ts_input(), and Botan::RandomNumberGenerator::randomize_with_ts_input().

   {
   this->add_entropy(input, input_len);
   this->randomize(output, output_len);
   }

randomize_with_ts_input()

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

virtualinherited

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.

Reimplemented in Botan::Stateful_RNG.

Definition at line 18 of file rng.cpp.

References Botan::RandomNumberGenerator::accepts_input(), Botan::OS::get_high_resolution_clock(), Botan::OS::get_system_timestamp_ns(), Botan::RandomNumberGenerator::randomize(), Botan::RandomNumberGenerator::randomize_with_input(), and Botan::store_le().

   {
   if(this->accepts_input())
      {
      /*
      Form additional input which is provided to the PRNG implementation
      to paramaterize the KDF output.
      */
      uint8_t additional_input[16] = { 0 };
      store_le(OS::get_system_timestamp_ns(), additional_input);
      store_le(OS::get_high_resolution_clock(), additional_input + 8);

      this->randomize_with_input(output, output_len, additional_input, sizeof(additional_input));
      }
   else
      {
      this->randomize(output, output_len);
      }
   }

reseed()

size_t Botan::RandomNumberGenerator::reseed ( Entropy_Sources &  srcs, size_t  poll_bits = BOTAN_RNG_RESEED_POLL_BITS, std::chrono::milliseconds  poll_timeout = BOTAN_RNG_RESEED_DEFAULT_TIMEOUT  )

virtualinherited

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

Reimplemented in Botan::Stateful_RNG, Botan::RDRAND_RNG, Botan::PKCS11::PKCS11_RNG, and Botan::AutoSeeded_RNG.

Definition at line 45 of file rng.cpp.

References Botan::RandomNumberGenerator::accepts_input(), and Botan::Entropy_Sources::poll().

Referenced by Botan::Stateful_RNG::reseed().

   {
   if(this->accepts_input())
      {
      return srcs.poll(*this, poll_bits, poll_timeout);
      }
   else
      {
      return 0;
      }
   }

reseed_from_rng()

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

virtualinherited

Reseed by reading specified bits from the RNG

Reimplemented in Botan::Stateful_RNG.

Definition at line 59 of file rng.cpp.

References Botan::RandomNumberGenerator::accepts_input(), Botan::RandomNumberGenerator::add_entropy(), and Botan::RandomNumberGenerator::randomize().

Referenced by botan_rng_reseed(), botan_rng_reseed_from_rng(), and Botan::Stateful_RNG::reseed_from_rng().

   {
   if(this->accepts_input())
      {
      secure_vector<uint8_t> buf(poll_bits / 8);
      rng.randomize(buf.data(), buf.size());
      this->add_entropy(buf.data(), buf.size());
      }
   }

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

• src/lib/rng/rng.h