Botan::TPM_RNG Class Reference

#include <tpm.h>

Inheritance diagram for Botan::TPM_RNG:

Public Member Functions
bool	accepts_input () const override
void	add_entropy (const uint8_t in[], size_t in_len) override
template<typename T >
void	add_entropy_T (const T &t)
virtual void	clear () final 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)
template<typename Alloc >
void	random_vec (std::vector< uint8_t, Alloc > &v, size_t bytes)
void	randomize (uint8_t out[], size_t out_len) 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)
	TPM_RNG (TPM_Context &ctx)

Detailed Description

Definition at line 78 of file tpm.h.

Constructor & Destructor Documentation

TPM_RNG()

Botan::TPM_RNG::TPM_RNG ( TPM_Context &  ctx )

inline

Definition at line 81 of file tpm.h.

: m_ctx(ctx) {}

Member Function Documentation

accepts_input()

bool Botan::TPM_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 83 of file tpm.h.

{ return true; }

add_entropy()

void Botan::TPM_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

Exceptions

Exception

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

Implements Botan::RandomNumberGenerator.

Definition at line 85 of file tpm.h.

         {
         m_ctx.stir_random(in, in_len);
         }

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 ( )

inlinefinaloverridevirtualinherited

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()

bool Botan::TPM_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 97 of file tpm.h.

{ return true; }

name()

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

inlineoverridevirtual

Returns

the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 95 of file tpm.h.

{ return "TPM_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 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()

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

inlineoverridevirtual

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

Implements Botan::RandomNumberGenerator.

Definition at line 90 of file tpm.h.

         {
         m_ctx.gen_random(out, out_len);
         }

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/prov/tpm/tpm.h