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

#include <rng.h>

Inheritance diagram for Botan::RandomNumberGenerator:
Botan::AutoSeeded_RNG Botan::Hardware_RNG Botan::Null_RNG Botan::Stateful_RNG Botan::System_RNG Botan::PKCS11::PKCS11_RNG Botan::RDRAND_RNG Botan::TPM_RNG Botan::HMAC_DRBG

Public Member Functions

virtual void add_entropy (const byte input[], size_t length)=0
 
template<typename T >
void add_entropy_T (const T &t)
 
virtual void clear ()=0
 
virtual bool is_seeded () const =0
 
virtual std::string name () const =0
 
byte next_byte ()
 
byte next_nonzero_byte ()
 
RandomNumberGeneratoroperator= (const RandomNumberGenerator &rng)=delete
 
secure_vector< byterandom_vec (size_t bytes)
 
virtual void randomize (byte output[], size_t length)=0
 
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)
 
 RandomNumberGenerator ()=default
 
 RandomNumberGenerator (const RandomNumberGenerator &rng)=delete
 
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)
 
virtual ~RandomNumberGenerator ()=default
 

Static Public Member Functions

static RandomNumberGeneratormake_rng ()
 

Detailed Description

An interface to a cryptographic random number generator

Definition at line 25 of file rng.h.

Constructor & Destructor Documentation

§ ~RandomNumberGenerator()

virtual Botan::RandomNumberGenerator::~RandomNumberGenerator ( )
virtualdefault

§ RandomNumberGenerator() [1/2]

Botan::RandomNumberGenerator::RandomNumberGenerator ( )
default

§ RandomNumberGenerator() [2/2]

Botan::RandomNumberGenerator::RandomNumberGenerator ( const RandomNumberGenerator rng)
delete

Member Function Documentation

§ add_entropy()

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

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

Implemented in Botan::Null_RNG, Botan::HMAC_DRBG, Botan::TPM_RNG, and Botan::AutoSeeded_RNG.

Referenced by Botan::System_RNG::add_entropy(), Botan::Stateful_RNG::initialize_with(), Botan::Darwin_SecRandom::poll(), Botan::Intel_Rdrand::poll(), Botan::Win32_CAPI_EntropySource::poll(), Botan::Device_EntropySource::poll(), Botan::ProcWalking_EntropySource::poll(), randomize_with_input(), and reseed_from_rng().

§ add_entropy_T()

template<typename T >
void Botan::RandomNumberGenerator::add_entropy_T ( const T &  t)
inline

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()

virtual void Botan::RandomNumberGenerator::clear ( )
pure virtual

Clear all internally held values of this RNG

Postcondition
is_seeded() == false

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

§ is_seeded()

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

Check whether this RNG is seeded.

Returns
true if this RNG was already seeded, false otherwise.

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

§ make_rng()

RandomNumberGenerator * Botan::RandomNumberGenerator::make_rng ( )
static

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()

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

§ next_byte()

byte Botan::RandomNumberGenerator::next_byte ( )
inline

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 ( )
inline
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

§ operator=()

RandomNumberGenerator& Botan::RandomNumberGenerator::operator= ( const RandomNumberGenerator rng)
delete

§ random_vec()

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

§ randomize()

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

§ randomize_with_input()

void Botan::RandomNumberGenerator::randomize_with_input ( byte  output[],
size_t  output_len,
const byte  input[],
size_t  input_len 
)
virtual

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 add_entropy(), and randomize().

Referenced by Botan::Stateful_RNG::randomize_with_ts_input(), and 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 
)
virtual

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(), 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 
)
virtual

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 
)
virtual

Reseed by reading specified bits from the RNG

Reimplemented in Botan::Stateful_RNG.

Definition at line 44 of file rng.cpp.

References add_entropy(), and 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 files: