Botan  1.11.34
Crypto and TLS for C++11
Public Member Functions | Static Public Member Functions | List of all members
Botan::Null_RNG Class Referencefinal

#include <rng.h>

Inheritance diagram for Botan::Null_RNG:
Botan::RandomNumberGenerator

Public Member Functions

void add_entropy (const byte[], 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
 
byte next_byte ()
 
byte next_nonzero_byte ()
 
secure_vector< byterandom_vec (size_t bytes)
 
void randomize (byte[], size_t) override
 
virtual void randomize_with_input (byte output[], size_t output_len, const byte input[], size_t input_len)
 
virtual void randomize_with_ts_input (byte 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 RandomNumberGeneratormake_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 187 of file rng.h.

Member Function Documentation

§ add_entropy()

void Botan::Null_RNG::add_entropy ( const byte  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
inputa byte array containg the entropy to be added
lengththe length of the byte array in

Implements Botan::RandomNumberGenerator.

Definition at line 199 of file rng.h.

199 {}

§ 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 60 of file rng.h.

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

61  {
62  this->add_entropy(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
63  }
virtual void add_entropy(const byte input[], size_t length)=0

§ 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 192 of file rng.h.

192 {}

§ 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 190 of file rng.h.

190 { 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 51 of file rng.cpp.

52  {
53 #if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
54  return new AutoSeeded_RNG;
55 #else
56  throw Exception("make_rng failed, no AutoSeeded_RNG in this build");
57 #endif
58  }

§ name()

std::string Botan::Null_RNG::name ( ) const
inlineoverridevirtual
Returns
the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 201 of file rng.h.

References Botan::BOTAN_DEPRECATED().

201 { return "Null_RNG"; }

§ next_byte()

byte Botan::RandomNumberGenerator::next_byte ( )
inlineinherited

Return a random byte

Returns
random byte

Definition at line 144 of file rng.h.

Referenced by Botan::Blinded_Point_Multiply::blinded_multiply(), and Botan::random_prime().

145  {
146  byte b;
147  this->randomize(&b, 1);
148  return b;
149  }
virtual void randomize(byte output[], size_t length)=0
std::uint8_t byte
Definition: types.h:31

§ next_nonzero_byte()

byte Botan::RandomNumberGenerator::next_nonzero_byte ( )
inlineinherited
Returns
a random byte that is not the zero byte

Definition at line 154 of file rng.h.

References Botan::BOTAN_DEPRECATED().

155  {
156  byte b = this->next_byte();
157  while(b == 0)
158  b = this->next_byte();
159  return b;
160  }
std::uint8_t byte
Definition: types.h:31

§ random_vec()

secure_vector<byte> Botan::RandomNumberGenerator::random_vec ( size_t  bytes)
inlineinherited

§ randomize()

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

Randomize a byte array.

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

Implements Botan::RandomNumberGenerator.

Definition at line 194 of file rng.h.

195  {
196  throw PRNG_Unseeded("Null_RNG called");
197  }

§ randomize_with_input()

void Botan::RandomNumberGenerator::randomize_with_input ( byte  output[],
size_t  output_len,
const byte  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
outputbuffer to hold the random output
output_lensize of the output buffer in bytes
inputentropy buffer to incorporate
input_lensize of the input buffer in bytes

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

Definition at line 30 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().

32  {
33  this->add_entropy(input, input_len);
34  this->randomize(output, output_len);
35  }
virtual void randomize(byte output[], size_t length)=0
virtual void add_entropy(const byte input[], size_t length)=0

§ randomize_with_ts_input()

void Botan::RandomNumberGenerator::randomize_with_ts_input ( byte  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 17 of file rng.cpp.

References Botan::OS::get_processor_timestamp(), Botan::OS::get_system_timestamp_ns(), Botan::RandomNumberGenerator::randomize_with_input(), and Botan::store_le().

Referenced by Botan::AutoSeeded_RNG::randomize().

18  {
19  /*
20  Form additional input which is provided to the PRNG implementation
21  to paramaterize the KDF output.
22  */
23  byte additional_input[16] = { 0 };
24  store_le(OS::get_system_timestamp_ns(), additional_input);
25  store_le(OS::get_processor_timestamp(), additional_input + 8);
26 
27  randomize_with_input(output, output_len, additional_input, sizeof(additional_input));
28  }
virtual void randomize_with_input(byte output[], size_t output_len, const byte input[], size_t input_len)
Definition: rng.cpp:30
void store_le(u16bit in, byte out[2])
Definition: loadstor.h:457
uint64_t get_processor_timestamp()
Definition: os_utils.cpp:44
uint64_t get_system_timestamp_ns()
Definition: os_utils.cpp:134
std::uint8_t byte
Definition: types.h:31

§ 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 37 of file rng.cpp.

References Botan::Entropy_Sources::poll().

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

40  {
41  return srcs.poll(*this, poll_bits, poll_timeout);
42  }

§ 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 44 of file rng.cpp.

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

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

45  {
46  secure_vector<byte> buf(poll_bits / 8);
47  rng.randomize(buf.data(), buf.size());
48  this->add_entropy(buf.data(), buf.size());
49  }
virtual void add_entropy(const byte input[], size_t length)=0

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