Botan::Hardware_RNG Class Reference

#include <rng.h>

Inheritance diagram for Botan::Hardware_RNG:

Public Member Functions
virtual bool	accepts_input () const =0
virtual void	add_entropy (const uint8_t input[], size_t length)=0
template<typename T >
void	add_entropy_T (const T &t)
virtual void	clear () final override
virtual bool	is_seeded () const =0
virtual std::string	name () const =0
uint8_t	next_byte ()
uint8_t	next_nonzero_byte ()
secure_vector< uint8_t >	random_vec (size_t bytes)
template<typename Alloc >
void	random_vec (std::vector< uint8_t, Alloc > &v, size_t bytes)
virtual void	randomize (uint8_t output[], size_t length)=0
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)

Detailed Description

Hardware_RNG exists to tag hardware RNG types (PKCS11_RNG, TPM_RNG, Processor_RNG)

Definition at line 216 of file rng.h.

Member Function Documentation

accepts_input()

virtual bool Botan::RandomNumberGenerator::accepts_input ( ) const

pure virtualinherited

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.

Implemented in Botan::PKCS11::PKCS11_RNG, Botan::TPM_RNG, Botan::AutoSeeded_RNG, Botan::Processor_RNG, Botan::Null_RNG, Botan::System_RNG, and Botan::Stateful_RNG.

Referenced by Botan::System_RNG::accepts_input(), Botan::RandomNumberGenerator::randomize_with_ts_input(), Botan::RandomNumberGenerator::reseed(), and Botan::RandomNumberGenerator::reseed_from_rng().

add_entropy()

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

pure virtualinherited

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

Exceptions

Exception

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

Implemented in Botan::TPM_RNG, Botan::AutoSeeded_RNG, Botan::System_RNG, Botan::Stateful_RNG, Botan::Processor_RNG, and Botan::Null_RNG.

Referenced by Botan::System_RNG::add_entropy(), botan_rng_add_entropy(), Botan::Getentropy::poll(), Botan::Intel_Rdseed::poll(), Botan::RandomNumberGenerator::randomize_with_input(), and Botan::RandomNumberGenerator::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 76 of file rng.h.

         {
         static_assert(std::is_standard_layout<T>::value && std::is_trivial<T>::value, "add_entropy_T data must be POD");
         this->add_entropy(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
         }

References T.

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

clear()

virtual void Botan::Hardware_RNG::clear ( )

inlinefinaloverridevirtual

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 219 of file rng.h.

{ /* no way to clear state of hardware RNG */ }

is_seeded()

virtual bool Botan::RandomNumberGenerator::is_seeded ( ) const

pure virtualinherited

Check whether this RNG is seeded.

Returns

true if this RNG was already seeded, false otherwise.

Implemented in Botan::PKCS11::PKCS11_RNG, Botan::TPM_RNG, Botan::AutoSeeded_RNG, Botan::Processor_RNG, Botan::Null_RNG, Botan::System_RNG, and Botan::Stateful_RNG.

Referenced by Botan::is_prime(), Botan::System_RNG::is_seeded(), and Botan::PointGFp_Base_Point_Precompute::mul().

name()

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

pure virtualinherited

Returns

the name of this RNG type

Implemented in Botan::PKCS11::PKCS11_RNG, Botan::TPM_RNG, Botan::AutoSeeded_RNG, Botan::ChaCha_RNG, Botan::HMAC_DRBG, Botan::Processor_RNG, Botan::Null_RNG, and Botan::System_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 187 of file rng.h.

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

References b.

Referenced by 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 199 of file rng.h.

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

References b.

Referenced by Botan::EME_PKCS1v15::pad().

random_vec() [1/2]

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

Exceptions

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

Definition at line 167 of file rng.h.

         {
         secure_vector<uint8_t> output;
         random_vec(output, bytes);
         return output;
         }

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::Kyber_PrivateKey::Kyber_PrivateKey(), Botan::OctetString::OctetString(), Botan::BigInt::randomize(), and Botan::TLS::Session_Manager_In_Memory::remove_all().

random_vec() [2/2]

template<typename Alloc >

void Botan::RandomNumberGenerator::random_vec ( std::vector< uint8_t, Alloc > &  v, size_t  bytes  )

inlineinherited

Definition at line 175 of file rng.h.

         {
         v.resize(bytes);
         this->randomize(v.data(), v.size());
         }

References v.

randomize()

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

pure virtualinherited

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.
length	the length of the byte array output in bytes.

Exceptions

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

Implemented in Botan::AutoSeeded_RNG, Botan::System_RNG, Botan::TPM_RNG, Botan::Processor_RNG, Botan::Stateful_RNG, and Botan::Null_RNG.

Referenced by Botan::TLS::Connection_Cipher_State::aead_nonce(), Botan::argon2_generate_pwhash(), botan_rng_get(), Botan::CryptoBox::encrypt(), Botan::generate_dsa_primes(), Botan::generate_passhash9(), Botan::TLS::make_hello_random(), Botan::newhope_keygen(), Botan::Roughtime::Nonce::Nonce(), Botan::EME_PKCS1v15::pad(), Botan::random_gf2m(), Botan::McEliece_PublicKey::random_plaintext_element(), Botan::random_prime(), Botan::Sodium::randombytes_buf(), Botan::System_RNG::randomize(), Botan::RandomNumberGenerator::randomize_with_input(), Botan::RandomNumberGenerator::randomize_with_ts_input(), Botan::Stateful_RNG::randomize_with_ts_input(), Botan::RandomNumberGenerator::reseed_from_rng(), Botan::KeyPair::signature_consistency_check(), and Botan::UUID::UUID().

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

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.

Reimplemented in Botan::AutoSeeded_RNG, and Botan::Stateful_RNG.

Definition at line 38 of file rng.cpp.

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

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

Referenced by Botan::RandomNumberGenerator::randomize_with_ts_input().

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.

Parameters

output	buffer to hold the random output
output_len	size of the output buffer in bytes

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.

Reimplemented in Botan::Stateful_RNG.

Definition at line 18 of file rng.cpp.

   {
   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);
      }
   }

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().

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.

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

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

Definition at line 45 of file rng.cpp.

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

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

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

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

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

Exceptions

Exception

if RNG accepts input but reseeding failed.

Reimplemented in Botan::Stateful_RNG.

Definition at line 59 of file rng.cpp.

   {
   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());
      }
   }

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().

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

• src/lib/rng/rng.h