Botan 3.13.0
Crypto and TLS for C&
Botan::AutoSeeded_RNG Class Referencefinal

#include <auto_rng.h>

Inheritance diagram for Botan::AutoSeeded_RNG:
Botan::RandomNumberGenerator

Public Member Functions

bool accepts_input () const override
void add_entropy (const uint8_t input[], size_t length)
void add_entropy (std::span< const uint8_t > input)
template<typename T>
void add_entropy_T (const T &t)
 AutoSeeded_RNG (AutoSeeded_RNG &&other) noexcept
 AutoSeeded_RNG (const AutoSeeded_RNG &other)=delete
BOTAN_FUTURE_EXPLICIT AutoSeeded_RNG (Entropy_Sources &entropy_sources, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval)
 AutoSeeded_RNG (RandomNumberGenerator &underlying_rng, Entropy_Sources &entropy_sources, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval)
BOTAN_FUTURE_EXPLICIT AutoSeeded_RNG (RandomNumberGenerator &underlying_rng, size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval)
BOTAN_FUTURE_EXPLICIT AutoSeeded_RNG (size_t reseed_interval=RandomNumberGenerator::DefaultReseedInterval)
void clear () override
void force_reseed ()
bool is_seeded () const override
std::string name () const override
uint8_t next_byte ()
uint8_t next_nonzero_byte ()
AutoSeeded_RNGoperator= (AutoSeeded_RNG &&other)=delete
AutoSeeded_RNGoperator= (const AutoSeeded_RNG &other)=delete
template<size_t bytes>
std::array< uint8_t, bytes > random_array ()
template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>
random_vec (size_t bytes)
void random_vec (std::span< uint8_t > v)
template<concepts::resizable_byte_buffer T>
void random_vec (T &v, size_t bytes)
void randomize (std::span< uint8_t > output)
void randomize (uint8_t output[], size_t length)
void randomize_with_input (std::span< uint8_t > output, std::span< const uint8_t > input)
void randomize_with_input (uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)
void randomize_with_ts_input (std::span< uint8_t > output)
void randomize_with_ts_input (uint8_t output[], size_t output_len)
size_t reseed (Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits, std::chrono::milliseconds=DefaultPollTimeout)
size_t reseed_from (Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
void reseed_from (RandomNumberGenerator &rng, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
virtual void reseed_from_rng (RandomNumberGenerator &rng, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
size_t reseed_from_sources (Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits) override
 ~AutoSeeded_RNG () override

Static Public Attributes

static constexpr size_t DefaultPollBits = 256
static constexpr auto DefaultPollTimeout = std::chrono::milliseconds(50)
static constexpr size_t DefaultReseedInterval = 1024

Detailed Description

A userspace PRNG

Definition at line 21 of file auto_rng.h.

Constructor & Destructor Documentation

◆ AutoSeeded_RNG() [1/6]

Botan::AutoSeeded_RNG::AutoSeeded_RNG ( size_t reseed_interval = RandomNumberGenerator::DefaultReseedInterval)

Uses the system RNG (if available) or else a default group of entropy sources (all other systems) to gather seed material.

Parameters
reseed_intervalspecifies a limit of how many times the RNG will be called before automatic reseeding is performed

Definition at line 68 of file auto_rng.cpp.

68 {
69#if defined(BOTAN_HAS_SYSTEM_RNG)
70 m_rng = std::make_unique<HMAC_DRBG>(auto_rng_hmac(), system_rng(), reseed_interval);
71#elif defined(BOTAN_HAS_ENTROPY_SOURCE)
72 m_rng = std::make_unique<HMAC_DRBG>(auto_rng_hmac(), Entropy_Sources::global_sources(), reseed_interval);
73#else
74 BOTAN_UNUSED(reseed_interval);
75 throw Not_Implemented("AutoSeeded_RNG default constructor not available due to no RNG or entropy sources");
76#endif
77
79}
#define BOTAN_UNUSED
Definition assert.h:144
static Entropy_Sources & global_sources()
RandomNumberGenerator & system_rng()

References BOTAN_UNUSED, force_reseed(), Botan::Entropy_Sources::global_sources(), and Botan::system_rng().

Referenced by AutoSeeded_RNG(), AutoSeeded_RNG(), operator=(), and operator=().

◆ AutoSeeded_RNG() [2/6]

Botan::AutoSeeded_RNG::AutoSeeded_RNG ( RandomNumberGenerator & underlying_rng,
size_t reseed_interval = RandomNumberGenerator::DefaultReseedInterval )

Create an AutoSeeded_RNG which will get seed material from some other RNG instance. For example you could provide a reference to the system RNG or a hardware RNG.

Parameters
underlying_rngis a reference to some RNG which will be used to perform the periodic reseeding
reseed_intervalspecifies a limit of how many times the RNG will be called before automatic reseeding is performed

Definition at line 48 of file auto_rng.cpp.

48 {
49 m_rng = std::make_unique<HMAC_DRBG>(auto_rng_hmac(), underlying_rng, reseed_interval);
50
52}

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

◆ AutoSeeded_RNG() [3/6]

Botan::AutoSeeded_RNG::AutoSeeded_RNG ( Entropy_Sources & entropy_sources,
size_t reseed_interval = RandomNumberGenerator::DefaultReseedInterval )

Create an AutoSeeded_RNG which will get seed material from a set of entropy sources.

Parameters
entropy_sourceswill be polled to perform reseeding periodically
reseed_intervalspecifies a limit of how many times the RNG will be called before automatic reseeding is performed

Definition at line 54 of file auto_rng.cpp.

54 {
55 m_rng = std::make_unique<HMAC_DRBG>(auto_rng_hmac(), entropy_sources, reseed_interval);
56
58}

References force_reseed().

◆ AutoSeeded_RNG() [4/6]

Botan::AutoSeeded_RNG::AutoSeeded_RNG ( RandomNumberGenerator & underlying_rng,
Entropy_Sources & entropy_sources,
size_t reseed_interval = RandomNumberGenerator::DefaultReseedInterval )

Create an AutoSeeded_RNG which will get seed material from both an underlying RNG and a set of entropy sources.

Parameters
underlying_rngis a reference to some RNG which will be used to perform the periodic reseeding
entropy_sourceswill be polled to perform reseeding periodically
reseed_intervalspecifies a limit of how many times the RNG will be called before automatic reseeding is performed

Definition at line 60 of file auto_rng.cpp.

62 {
63 m_rng = std::make_unique<HMAC_DRBG>(auto_rng_hmac(), underlying_rng, entropy_sources, reseed_interval);
64
66}

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

◆ AutoSeeded_RNG() [5/6]

Botan::AutoSeeded_RNG::AutoSeeded_RNG ( const AutoSeeded_RNG & other)
delete

References AutoSeeded_RNG().

◆ AutoSeeded_RNG() [6/6]

Botan::AutoSeeded_RNG::AutoSeeded_RNG ( AutoSeeded_RNG && other)
defaultnoexcept

Move constructor

References AutoSeeded_RNG().

◆ ~AutoSeeded_RNG()

Botan::AutoSeeded_RNG::~AutoSeeded_RNG ( )
overridedefault

Member Function Documentation

◆ accepts_input()

bool Botan::AutoSeeded_RNG::accepts_input ( ) const
inlineoverridevirtual

Test whether this RNG accepts externally provided input

Returns
false if this RNG is known to ignore provided inputs

Implements Botan::RandomNumberGenerator.

Definition at line 33 of file auto_rng.h.

33{ return true; }

◆ add_entropy() [1/2]

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

Incorporate some additional data into the RNG state

Parameters
inputa byte array containing the entropy to be added
lengththe number of bytes in input

Definition at line 121 of file rng.h.

121{ this->add_entropy(std::span(input, length)); }
void add_entropy(std::span< const uint8_t > input)
Definition rng.h:114

References add_entropy().

Referenced by add_entropy().

◆ add_entropy() [2/2]

void Botan::RandomNumberGenerator::add_entropy ( std::span< const uint8_t > input)
inlineinherited

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 containing the entropy to be added
Exceptions
Exceptionmay throw if the RNG accepts input, but adding the entropy failed.

Definition at line 114 of file rng.h.

114{ this->fill_bytes_with_input({}, input); }
virtual void fill_bytes_with_input(std::span< uint8_t > output, std::span< const uint8_t > input)=0

References fill_bytes_with_input().

Referenced by add_entropy_T(), Botan::ChaCha_RNG::ChaCha_RNG(), Botan::Stateful_RNG::initialize_with(), Botan::Getentropy::poll(), Botan::Intel_Rdseed::poll(), and reseed_from_rng().

◆ 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 128 of file rng.h.

128 {
129 this->add_entropy(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
130 }

References add_entropy().

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

◆ clear()

void Botan::AutoSeeded_RNG::clear ( )
overridevirtual

Clear all internally held values of this RNG

Implements Botan::RandomNumberGenerator.

Definition at line 94 of file auto_rng.cpp.

94 {
95 m_rng->clear();
96}

◆ force_reseed()

void Botan::AutoSeeded_RNG::force_reseed ( )

Mark state as requiring a reseed on next use

Definition at line 81 of file auto_rng.cpp.

81 {
82 m_rng->force_reseed();
83 m_rng->next_byte();
84
85 if(!m_rng->is_seeded()) {
86 throw Internal_Error("AutoSeeded_RNG reseeding failed");
87 }
88}

Referenced by AutoSeeded_RNG(), AutoSeeded_RNG(), AutoSeeded_RNG(), and AutoSeeded_RNG().

◆ is_seeded()

bool Botan::AutoSeeded_RNG::is_seeded ( ) const
overridevirtual

Test whether this RNG has been seeded

Returns
true if this RNG is seeded and ready for use

Implements Botan::RandomNumberGenerator.

Definition at line 90 of file auto_rng.cpp.

90 {
91 return m_rng->is_seeded();
92}

◆ name()

std::string Botan::AutoSeeded_RNG::name ( ) const
overridevirtual

Return the name of this RNG type

Returns
the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 98 of file auto_rng.cpp.

98 {
99 return m_rng->name();
100}

◆ next_byte()

uint8_t Botan::RandomNumberGenerator::next_byte ( )
inlineinherited

Return a random byte

Returns
random byte
Exceptions
PRNG_Unseededif the RNG fails because it has not enough entropy
Exceptionif the RNG fails

Definition at line 292 of file rng.h.

292 {
293 uint8_t b = 0;
294 this->fill_bytes_with_input(std::span(&b, 1), {});
295 return b;
296 }

References fill_bytes_with_input().

Referenced by next_nonzero_byte(), and Botan::random_prime().

◆ next_nonzero_byte()

uint8_t Botan::RandomNumberGenerator::next_nonzero_byte ( )
inlineinherited

Generate a single random byte which is not zero

Returns
a random byte that is greater than zero
Exceptions
PRNG_Unseededif the RNG fails because it has not enough entropy
Exceptionif the RNG fails

Definition at line 304 of file rng.h.

304 {
305 uint8_t b = this->next_byte();
306 while(b == 0) {
307 b = this->next_byte();
308 }
309 return b;
310 }

References next_byte().

◆ operator=() [1/2]

AutoSeeded_RNG & Botan::AutoSeeded_RNG::operator= ( AutoSeeded_RNG && other)
delete

References AutoSeeded_RNG().

◆ operator=() [2/2]

AutoSeeded_RNG & Botan::AutoSeeded_RNG::operator= ( const AutoSeeded_RNG & other)
delete

References AutoSeeded_RNG().

◆ random_array()

template<size_t bytes>
std::array< uint8_t, bytes > Botan::RandomNumberGenerator::random_array ( )
inlineinherited

Create a std::array of bytes random bytes

Definition at line 280 of file rng.h.

280 {
281 std::array<uint8_t, bytes> result{};
282 random_vec(result);
283 return result;
284 }
void random_vec(std::span< uint8_t > v)
Definition rng.h:244

References random_vec().

◆ random_vec() [1/3]

template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>
T Botan::RandomNumberGenerator::random_vec ( size_t bytes)
inlineinherited

Create some byte container type and fill it with some random bytes.

Template Parameters
Tthe desired byte container type (e.g std::vector<uint8_t>)
Parameters
bytesnumber of random bytes to initialize the container with
Returns
a container of type T with bytes random bytes
Exceptions
Exceptionif RNG or memory allocation fails

Definition at line 270 of file rng.h.

270 {
271 T result;
272 random_vec(result, bytes);
273 return result;
274 }

References random_vec().

◆ random_vec() [2/3]

◆ random_vec() [3/3]

template<concepts::resizable_byte_buffer T>
void Botan::RandomNumberGenerator::random_vec ( T & v,
size_t bytes )
inlineinherited

Resize a given byte container to bytes and fill it with random bytes

Template Parameters
Tthe desired byte container type (e.g std::vector<uint8_t>)
Parameters
vthe container to be filled with bytes random bytes
bytesnumber of random bytes to initialize the container with
Exceptions
Exceptionif RNG or memory allocation fails

Definition at line 255 of file rng.h.

255 {
256 v.resize(bytes);
257 random_vec(v);
258 }

References random_vec().

◆ randomize() [1/2]

◆ randomize() [2/2]

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

Randomize a byte array

Parameters
outputthe byte array to hold the random output
lengththe number of bytes to generate

Definition at line 93 of file rng.h.

93{ this->randomize(std::span(output, length)); }

References randomize().

Referenced by randomize().

◆ randomize_with_input() [1/2]

void Botan::RandomNumberGenerator::randomize_with_input ( std::span< uint8_t > output,
std::span< const uint8_t > input )
inlineinherited

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
inputentropy buffer to incorporate
Exceptions
PRNG_Unseededif the RNG fails because it has not enough entropy
Exceptionif the RNG fails
Exceptionmay throw if the RNG accepts input, but adding the entropy failed.

Definition at line 148 of file rng.h.

148 {
149 this->fill_bytes_with_input(output, input);
150 }

References fill_bytes_with_input().

Referenced by Botan::System_RNG::fill_bytes_with_input(), and randomize_with_input().

◆ randomize_with_input() [2/2]

void Botan::RandomNumberGenerator::randomize_with_input ( uint8_t output[],
size_t output_len,
const uint8_t input[],
size_t input_len )
inlineinherited

Randomize a byte array, first incorporating additional input

Parameters
outputthe byte array to hold the random output
output_lenthe number of bytes to generate
inputa byte array containing the entropy to be added
input_lenthe number of bytes in input

Definition at line 159 of file rng.h.

159 {
160 this->randomize_with_input(std::span(output, output_len), std::span(input, input_len));
161 }
void randomize_with_input(std::span< uint8_t > output, std::span< const uint8_t > input)
Definition rng.h:148

References randomize_with_input().

◆ randomize_with_ts_input() [1/2]

void Botan::RandomNumberGenerator::randomize_with_ts_input ( std::span< uint8_t > output)
inherited

This calls randomize_with_input using system specific values

This first attempts to provide input to the underlying RNG from some system specific source. If a system RNG is available, it is queried and the output from the system RNG is used as the additional input. Otherwise 12 bytes consisting of the local clock plus the current process ID are used.

For a stateful RNG that was already correctly seeded with sufficient cryptographically secure material, using non-random but potentially unique data as 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 some input, even predictable input, their outputs will diverge.

Parameters
outputbuffer to hold the random output
Exceptions
PRNG_Unseededif the RNG fails because it has not enough entropy
Exceptionif the RNG fails
Exceptionmay throw if the RNG accepts input, but adding the entropy failed.

Definition at line 26 of file rng.cpp.

26 {
27 if(this->accepts_input()) {
28 std::array<uint8_t, 16> additional_input = {0};
29
30#if defined(BOTAN_HAS_SYSTEM_RNG)
31 // If we have a system RNG just read 128 bits from that
32 system_rng().randomize(additional_input);
33 constexpr size_t written = additional_input.size();
34#elif defined(BOTAN_HAS_OS_UTILS)
35 // Otherwise take clock + pid
36 const uint64_t clock = OS::get_high_resolution_clock();
37 const uint32_t pid = OS::get_process_id(); // 0 if no PIDs on this system
38
39 store_le(std::span{additional_input}.first<8>(), clock);
40 store_le(std::span{additional_input}.subspan<8, 4>(), pid);
41 const size_t written = 8 + (pid != 0) ? 4 : 0;
42#else
43 // Nothing to use in this case
44 constexpr size_t written = 0;
45#endif
46
47 this->fill_bytes_with_input(output, std::span{additional_input}.first(written));
48 } else {
49 this->fill_bytes_with_input(output, {});
50 }
51}
virtual bool accepts_input() const =0
uint64_t BOTAN_TEST_API get_high_resolution_clock()
Definition os_utils.cpp:272
uint32_t BOTAN_TEST_API get_process_id()
Definition os_utils.cpp:77
constexpr auto store_le(ParamTs &&... params)
Definition loadstor.h:736

References accepts_input(), fill_bytes_with_input(), Botan::OS::get_high_resolution_clock(), Botan::OS::get_process_id(), randomize(), Botan::store_le(), and Botan::system_rng().

Referenced by randomize_with_ts_input().

◆ randomize_with_ts_input() [2/2]

void Botan::RandomNumberGenerator::randomize_with_ts_input ( uint8_t output[],
size_t output_len )
inlineinherited

Randomize a byte array, using timestamps as additional input

Parameters
outputthe byte array to hold the random output
output_lenthe number of bytes to generate

Definition at line 190 of file rng.h.

190 {
191 this->randomize_with_ts_input(std::span(output, output_len));
192 }
void randomize_with_ts_input(std::span< uint8_t > output)
Definition rng.cpp:26

References randomize_with_ts_input().

◆ reseed()

size_t Botan::RandomNumberGenerator::reseed ( Entropy_Sources & srcs,
size_t poll_bits = RandomNumberGenerator::DefaultPollBits,
std::chrono::milliseconds = DefaultPollTimeout )
inlineinherited

Poll provided sources for up to poll_bits bits of entropy. Returns estimate of the number of bits collected.

Sets the seeded state to true if enough entropy was added.

TODO(Botan4) remove this function

Definition at line 337 of file rng.h.

339 {
340 return reseed_from(srcs, poll_bits);
341 }
size_t reseed_from(Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
Definition rng.h:219

References DefaultPollBits, DefaultPollTimeout, RandomNumberGenerator(), reseed(), and reseed_from().

Referenced by reseed().

◆ reseed_from() [1/2]

size_t Botan::RandomNumberGenerator::reseed_from ( Entropy_Sources & srcs,
size_t poll_bits = RandomNumberGenerator::DefaultPollBits )
inlineinherited

Poll provided sources for up to poll_bits bits of entropy. Returns estimate of the number of bits collected. Sets the seeded state to true if enough entropy was added.

Exceptions
Exceptionif RNG accepts input but reseeding failed.

Definition at line 219 of file rng.h.

219 {
220 return reseed_from_sources(srcs, poll_bits);
221 }
virtual size_t reseed_from_sources(Entropy_Sources &srcs, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
Definition rng.cpp:53

References DefaultPollBits, and reseed_from_sources().

Referenced by reseed().

◆ reseed_from() [2/2]

void Botan::RandomNumberGenerator::reseed_from ( RandomNumberGenerator & rng,
size_t poll_bits = RandomNumberGenerator::DefaultPollBits )
inlineinherited

Reseed by reading specified bits from the RNG

Sets the seeded state to true if enough entropy was added.

Exceptions
Exceptionif RNG accepts input but reseeding failed.

Definition at line 230 of file rng.h.

230 {
231 return reseed_from_rng(rng, poll_bits);
232 }
virtual void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=RandomNumberGenerator::DefaultPollBits)
Definition rng.cpp:65

References DefaultPollBits, RandomNumberGenerator(), and reseed_from_rng().

◆ reseed_from_rng()

void Botan::RandomNumberGenerator::reseed_from_rng ( RandomNumberGenerator & rng,
size_t poll_bits = RandomNumberGenerator::DefaultPollBits )
virtualinherited

Reseed by reading specified bits from the RNG

Sets the seeded state to true if enough entropy was added.

Exceptions
Exceptionif RNG accepts input but reseeding failed.

Reimplemented in Botan::Stateful_RNG.

Definition at line 65 of file rng.cpp.

65 {
66 if(this->accepts_input()) {
67 this->add_entropy(rng.random_vec(poll_bits / 8));
68 }
69}

References accepts_input(), add_entropy(), random_vec(), and RandomNumberGenerator().

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

◆ reseed_from_sources()

size_t Botan::AutoSeeded_RNG::reseed_from_sources ( Entropy_Sources & srcs,
size_t poll_bits = RandomNumberGenerator::DefaultPollBits )
overridevirtual

Poll the provided sources for entropy and reseed from them

Parameters
srcsthe entropy sources to poll
poll_bitsthe number of bits to collect
Returns
estimate of the number of bits collected

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 102 of file auto_rng.cpp.

102 {
103 return m_rng->reseed_from_sources(srcs, poll_bits);
104}

Member Data Documentation

◆ DefaultPollBits

size_t Botan::RandomNumberGenerator::DefaultPollBits = 256
staticconstexprinherited

Number of entropy bits polled for reseeding userspace RNGs like HMAC_DRBG

Definition at line 50 of file rng.h.

Referenced by reseed(), reseed_from(), and reseed_from().

◆ DefaultPollTimeout

auto Botan::RandomNumberGenerator::DefaultPollTimeout = std::chrono::milliseconds(50)
staticconstexprinherited

Default poll timeout

Definition at line 326 of file rng.h.

Referenced by reseed().

◆ DefaultReseedInterval

size_t Botan::RandomNumberGenerator::DefaultReseedInterval = 1024
staticconstexprinherited

Userspace RNGs like HMAC_DRBG will reseed after a specified number of outputs are generated. Set to zero to disable automatic reseeding.

Definition at line 45 of file rng.h.


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