Botan::Randpool Class Reference

#include <randpool.h>

Inheritance diagram for Botan::Randpool:

Public Member Functions
void	add_entropy (const byte input[], size_t length)
void	add_entropy_source (EntropySource *es)
void	clear ()
bool	is_seeded () const
std::string	name () const
byte	next_byte ()
SecureVector< byte >	random_vec (size_t bytes)
void	randomize (byte[], size_t)
	Randpool (BlockCipher *cipher, MessageAuthenticationCode *mac, size_t pool_blocks=32, size_t iterations_before_reseed=128)
void	reseed (size_t bits_to_collect)
	~Randpool ()

Static Public Member Functions
static RandomNumberGenerator *	make_rng ()

Detailed Description

Randpool

Definition at line 21 of file randpool.h.

Constructor & Destructor Documentation

Randpool()

Botan::Randpool::Randpool	(	BlockCipher *	cipher,
		MessageAuthenticationCode *	mac,
		size_t	pool_blocks = 32,
		size_t	iterations_before_reseed = 128 )

Parameters

cipher	a block cipher to use
mac	a message authentication code to use
pool_blocks	how many cipher blocks to use for the pool
iterations_before_reseed	how many times we'll use the internal state to generate output before reseeding

Definition at line 169 of file randpool.cpp.

                                              :
   ITERATIONS_BEFORE_RESEED(iter_before_reseed),
   POOL_BLOCKS(pool_blocks),
   cipher(cipher_in),
   mac(mac_in)
   {
   const size_t BLOCK_SIZE = cipher->block_size();
   const size_t OUTPUT_LENGTH = mac->output_length();
 
   if(OUTPUT_LENGTH < BLOCK_SIZE ||
      !cipher->valid_keylength(OUTPUT_LENGTH) ||
      !mac->valid_keylength(OUTPUT_LENGTH))
      {
      delete cipher;
      delete mac;
      throw Internal_Error("Randpool: Invalid algorithm combination");
      }
 
   buffer.resize(BLOCK_SIZE);
   pool.resize(POOL_BLOCKS * BLOCK_SIZE);
   counter.resize(12);
   seeded = false;
   }

~Randpool()

Botan::Randpool::~Randpool

(

)

Definition at line 199 of file randpool.cpp.

   {
   delete cipher;
   delete mac;
 
   std::for_each(entropy_sources.begin(), entropy_sources.end(),
                 del_fun<EntropySource>());
   }

Member Function Documentation

add_entropy()

void Botan::Randpool::add_entropy ( const byte in[], size_t length )

virtual

Add entropy to this RNG.

Parameters

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

Implements Botan::RandomNumberGenerator.

Definition at line 127 of file randpool.cpp.

   {
   SecureVector<byte> mac_val = mac->process(input, length);
   xor_buf(pool, mac_val, mac_val.size());
   mix_pool();
 
   if(length)
      seeded = true;
   }

References Botan::MemoryRegion< T >::size(), and Botan::xor_buf().

add_entropy_source()

void Botan::Randpool::add_entropy_source ( EntropySource * source )

virtual

Add this entropy source to the RNG object

Parameters

source

the entropy source which will be retained and used by RNG

Implements Botan::RandomNumberGenerator.

Definition at line 140 of file randpool.cpp.

   {
   entropy_sources.push_back(src);
   }

clear()

void Botan::Randpool::clear ( )

virtual

Clear all internally held values of this RNG.

Implements Botan::RandomNumberGenerator.

Definition at line 148 of file randpool.cpp.

   {
   cipher->clear();
   mac->clear();
   zeroise(pool);
   zeroise(buffer);
   zeroise(counter);
   seeded = false;
   }

References Botan::zeroise().

is_seeded()

bool Botan::Randpool::is_seeded ( ) const

inlinevirtual

Check whether this RNG is seeded.

Returns

true if this RNG was already seeded, false otherwise.

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 25 of file randpool.h.

{ return seeded; }

Referenced by randomize().

make_rng()

RandomNumberGenerator * Botan::RandomNumberGenerator::make_rng ( )

staticinherited

Create a seeded and active RNG object for general application use

Definition at line 29 of file rng.cpp.

   {
#if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
   return new AutoSeeded_RNG;
#endif
 
   throw Algorithm_Not_Found("RandomNumberGenerator::make_rng - no RNG found");
   }

References Botan::Algorithm_Not_Found::Algorithm_Not_Found(), and RandomNumberGenerator().

name()

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

virtual

Return the name of this object

Implements Botan::RandomNumberGenerator.

Definition at line 161 of file randpool.cpp.

   {
   return "Randpool(" + cipher->name() + "," + mac->name() + ")";
   }

Referenced by randomize().

next_byte()

byte Botan::RandomNumberGenerator::next_byte ( )

inherited

Return a random byte

Returns

random byte

Definition at line 19 of file rng.cpp.

   {
   byte out;
   this->randomize(&out, 1);
   return out;
   }

References randomize().

Referenced by Botan::random_prime().

random_vec()

SecureVector< byte > 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 40 of file rng.h.

         {
         SecureVector<byte> output(bytes);
         randomize(&output[0], output.size());
         return output;
         }

References randomize(), and Botan::MemoryRegion< T >::size().

Referenced by Botan::Client_Hello::Client_Hello(), Botan::Client_Key_Exchange::Client_Key_Exchange(), Botan::KeyPair::encryption_consistency_check(), Botan::generate_bcrypt(), Botan::generate_dsa_primes(), Botan::OctetString::OctetString(), Botan::Client_Key_Exchange::pre_master_secret(), Botan::BigInt::randomize(), Botan::Server_Hello::Server_Hello(), and Botan::KeyPair::signature_consistency_check().

randomize()

void Botan::Randpool::randomize ( byte output[], size_t length )

virtual

Randomize a byte array.

Parameters

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

Implements Botan::RandomNumberGenerator.

Definition at line 32 of file randpool.cpp.

   {
   if(!is_seeded())
      throw PRNG_Unseeded(name());
 
   update_buffer();
   while(length)
      {
      const size_t copied = std::min<size_t>(length, buffer.size());
      copy_mem(out, &buffer[0], copied);
      out += copied;
      length -= copied;
      update_buffer();
      }
   }

References Botan::copy_mem(), is_seeded(), name(), and Botan::PRNG_Unseeded::PRNG_Unseeded().

reseed()

void Botan::Randpool::reseed ( size_t bits_to_collect )

virtual

Seed this RNG using the entropy sources it contains.

Parameters

bits_to_collect

is the number of bits of entropy to attempt to gather from the entropy sources

Implements Botan::RandomNumberGenerator.

Definition at line 100 of file randpool.cpp.

   {
   Entropy_Accumulator_BufferedComputation accum(*mac, poll_bits);
 
   if(!entropy_sources.empty())
      {
      size_t poll_attempt = 0;
 
      while(!accum.polling_goal_achieved() && poll_attempt < poll_bits)
         {
         entropy_sources[poll_attempt % entropy_sources.size()]->poll(accum);
         ++poll_attempt;
         }
      }
 
   SecureVector<byte> mac_val = mac->final();
 
   xor_buf(pool, mac_val, mac_val.size());
   mix_pool();
 
   if(accum.bits_collected() >= poll_bits)
      seeded = true;
   }

References Botan::Entropy_Accumulator::bits_collected(), Botan::Entropy_Accumulator::polling_goal_achieved(), Botan::MemoryRegion< T >::size(), and Botan::xor_buf().

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

• src/rng/randpool/randpool.h
• src/rng/randpool/randpool.cpp