Botan::Processor_RNG Class Reference

#include <processor_rng.h>

Inheritance diagram for Botan::Processor_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)
virtual void	clear () final override
bool	is_seeded () const override
std::string	name () const override
uint8_t	next_byte ()
uint8_t	next_nonzero_byte ()
	Processor_RNG ()
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)
size_t	reseed (Entropy_Sources &, size_t, std::chrono::milliseconds) override
virtual void	reseed_from_rng (RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS)

Static Public Member Functions
static bool	available ()
static RandomNumberGenerator *	make_rng ()

Detailed Description

Directly invokes a CPU specific instruction to generate random numbers. On x86, the RDRAND instruction is used. on POWER, the DARN instruction is used.

Definition at line 19 of file processor_rng.h.

Constructor & Destructor Documentation

Processor_RNG()

Botan::Processor_RNG::Processor_RNG

(

)

Constructor will throw if CPU does not have RDRAND bit set

Definition at line 140 of file processor_rng.cpp.

References available().

   {
   if(!Processor_RNG::available())
      throw Invalid_State("Current CPU does not support RNG instruction");
   }

Member Function Documentation

accepts_input()

bool Botan::Processor_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 32 of file processor_rng.h.

{ return false; }

add_entropy()

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

overridevirtual

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 146 of file processor_rng.cpp.

   {
   /* no way to add entropy */
   }

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 69 of file rng.h.

References T.

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

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

available()

bool Botan::Processor_RNG::available ( )

static

Return true if RNG instruction is available on the current processor

Definition at line 100 of file processor_rng.cpp.

Referenced by Botan::RDRAND_RNG::available(), botan_rng_init(), Botan::Entropy_Source::create(), and Processor_RNG().

   {
#if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY)
   return CPUID::has_rdrand();
#elif defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY)
   return CPUID::has_darn_rng();
#else
   return false;
#endif
   }

clear()

virtual void Botan::Hardware_RNG::clear ( )

inlinefinaloverridevirtualinherited

Clear all internally held values of this RNG

Postcondition

is_seeded() == false

Implements Botan::RandomNumberGenerator.

Definition at line 199 of file rng.h.

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

is_seeded()

bool Botan::Processor_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 33 of file processor_rng.h.

{ return true; }

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 Not_Implemented("make_rng failed, no AutoSeeded_RNG in this build");
#endif
   }

name()

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

overridevirtual

Returns

the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 111 of file processor_rng.cpp.

   {
#if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY)
   return "rdrand";
#elif defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY)
   return "darn";
#else
   return "hwrng";
#endif
   }

next_byte()

uint8_t Botan::RandomNumberGenerator::next_byte ( )

inlineinherited

Return a random byte

Returns

random byte

Definition at line 161 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 171 of file rng.h.

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

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

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

Definition at line 143 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;
         random_vec(output, bytes);
         return output;
         }

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 151 of file rng.h.

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

randomize()

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

overridevirtual

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 122 of file processor_rng.cpp.

References Botan::get_byte(), and Botan::store_le().

Referenced by Botan::RDRAND_RNG::randomize(), Botan::RDRAND_RNG::rdrand(), and Botan::RDRAND_RNG::rdrand_status().

   {
   while(out_len >= sizeof(hwrng_output))
      {
      const hwrng_output r = read_hwrng();
      store_le(r, out);
      out += sizeof(hwrng_output);
      out_len -= sizeof(hwrng_output);
      }

   if(out_len > 0) // at most sizeof(hwrng_output)-1
      {
      const hwrng_output r = read_hwrng();
      for(size_t i = 0; i != out_len; ++i)
         out[i] = get_byte(i, r);
      }
   }

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::Stateful_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::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::Processor_RNG::reseed ( Entropy_Sources &  srcs, size_t  poll_bits, std::chrono::milliseconds  poll_timeout  )

overridevirtual

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 from Botan::RandomNumberGenerator.

Definition at line 151 of file processor_rng.cpp.

   {
   /* no way to add entropy */
   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 files:

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