Botan 3.3.0
Crypto and TLS for C&
Public Member Functions | Protected Member Functions | List of all members
Botan::ChaCha_RNG Class Referencefinal

#include <chacha_rng.h>

Inheritance diagram for Botan::ChaCha_RNG:
Botan::Stateful_RNG Botan::RandomNumberGenerator

Public Member Functions

bool accepts_input () const final
 
void add_entropy (const uint8_t input[], size_t length)
 
void add_entropy (std::span< const uint8_t > input)
 
template<typename T >
requires std::is_standard_layout<T>::value && std::is_trivial<T>::value
void add_entropy_T (const T &t)
 
 ChaCha_RNG ()
 
 ChaCha_RNG (Entropy_Sources &entropy_sources, size_t reseed_interval=BOTAN_RNG_DEFAULT_RESEED_INTERVAL)
 
 ChaCha_RNG (RandomNumberGenerator &underlying_rng, Entropy_Sources &entropy_sources, size_t reseed_interval=BOTAN_RNG_DEFAULT_RESEED_INTERVAL)
 
 ChaCha_RNG (RandomNumberGenerator &underlying_rng, size_t reseed_interval=BOTAN_RNG_DEFAULT_RESEED_INTERVAL)
 
 ChaCha_RNG (std::span< const uint8_t > seed)
 
void clear () final
 
void force_reseed ()
 
void initialize_with (const uint8_t input[], size_t length)
 
void initialize_with (std::span< const uint8_t > input)
 
bool is_seeded () const final
 
size_t max_number_of_bytes_per_request () const override
 
std::string name () const override
 
uint8_t next_byte ()
 
uint8_t next_nonzero_byte ()
 
template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>
requires std::default_initializable<T>
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=BOTAN_RNG_RESEED_POLL_BITS, std::chrono::milliseconds poll_timeout=BOTAN_RNG_RESEED_DEFAULT_TIMEOUT) override
 
void reseed_from_rng (RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS) final
 
size_t reseed_interval () const
 
size_t security_level () const override
 

Protected Member Functions

void reseed_check ()
 

Detailed Description

ChaCha_RNG is a very fast but completely ad-hoc RNG created by creating a 256-bit random value and using it as a key for ChaCha20.

The RNG maintains two 256-bit keys, one for HMAC_SHA256 (HK) and the other for ChaCha20 (CK). To compute a new key in response to reseeding request or add_entropy calls, ChaCha_RNG computes CK' = HMAC_SHA256(HK, input_material) Then a new HK' is computed by running ChaCha20 with the new key to output 32 bytes: HK' = ChaCha20(CK')

Now output can be produced by continuing to produce output with ChaCha20 under CK'

The first HK (before seeding occurs) is taken as the all zero value.

Warning
This RNG construction is probably fine but is non-standard. The primary reason to use it is in cases where the other RNGs are not fast enough.

Definition at line 40 of file chacha_rng.h.

Constructor & Destructor Documentation

◆ ChaCha_RNG() [1/5]

Botan::ChaCha_RNG::ChaCha_RNG ( )

Automatic reseeding is disabled completely, as it has no access to any source for seed material.

If a fork is detected, the RNG will be unable to reseed itself in response. In this case, an exception will be thrown rather than generating duplicated output.

Definition at line 12 of file chacha_rng.cpp.

12 : Stateful_RNG() {
13 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
14 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
15 clear();
16}
static std::unique_ptr< MessageAuthenticationCode > create_or_throw(std::string_view algo_spec, std::string_view provider="")
Definition mac.cpp:148
static std::unique_ptr< StreamCipher > create_or_throw(std::string_view algo_spec, std::string_view provider="")

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), and Botan::StreamCipher::create_or_throw().

◆ ChaCha_RNG() [2/5]

Botan::ChaCha_RNG::ChaCha_RNG ( std::span< const uint8_t > seed)

Provide an initial seed to the RNG, without providing an underlying RNG or entropy source. Automatic reseeding is disabled completely, as it has no access to any source for seed material.

If a fork is detected, the RNG will be unable to reseed itself in response. In this case, an exception will be thrown rather than generating duplicated output.

Parameters
seedthe seed material, should be at least 256 bits

Definition at line 18 of file chacha_rng.cpp.

18 : Stateful_RNG() {
19 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
20 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
21 clear();
22 add_entropy(seed);
23}
void add_entropy(std::span< const uint8_t > input)
Definition rng.h:75

References Botan::RandomNumberGenerator::add_entropy(), Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), and Botan::StreamCipher::create_or_throw().

◆ ChaCha_RNG() [3/5]

Botan::ChaCha_RNG::ChaCha_RNG ( RandomNumberGenerator & underlying_rng,
size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL )

Automatic reseeding from underlying_rng will take place after reseed_interval many requests or after a fork was detected.

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 25 of file chacha_rng.cpp.

25 :
26 Stateful_RNG(underlying_rng, reseed_interval) {
27 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
28 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
29 clear();
30}
size_t reseed_interval() const

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), and Botan::StreamCipher::create_or_throw().

◆ ChaCha_RNG() [4/5]

Botan::ChaCha_RNG::ChaCha_RNG ( Entropy_Sources & entropy_sources,
size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL )

Automatic reseeding from entropy_sources will take place after reseed_interval many requests or after a fork was detected.

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 41 of file chacha_rng.cpp.

41 :
42 Stateful_RNG(entropy_sources, reseed_interval) {
43 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
44 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
45 clear();
46}

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), and Botan::StreamCipher::create_or_throw().

◆ ChaCha_RNG() [5/5]

Botan::ChaCha_RNG::ChaCha_RNG ( RandomNumberGenerator & underlying_rng,
Entropy_Sources & entropy_sources,
size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL )

Automatic reseeding from underlying_rng and entropy_sources will take place after reseed_interval many requests or after a fork was detected.

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 32 of file chacha_rng.cpp.

34 :
35 Stateful_RNG(underlying_rng, entropy_sources, reseed_interval) {
36 m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
37 m_chacha = StreamCipher::create_or_throw("ChaCha(20)");
38 clear();
39}

References Botan::Stateful_RNG::clear(), Botan::MessageAuthenticationCode::create_or_throw(), and Botan::StreamCipher::create_or_throw().

Member Function Documentation

◆ accepts_input()

bool Botan::Stateful_RNG::accepts_input ( ) const
inlinefinalvirtualinherited

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 71 of file stateful_rng.h.

71{ return true; }

◆ add_entropy() [1/2]

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

Definition at line 77 of file rng.h.

77{ this->add_entropy(std::span(input, length)); }

References Botan::RandomNumberGenerator::add_entropy().

Referenced by Botan::RandomNumberGenerator::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 75 of file rng.h.

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

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

◆ add_entropy_T()

template<typename T >
requires std::is_standard_layout<T>::value && std::is_trivial<T>::value
void Botan::RandomNumberGenerator::add_entropy_T ( const T & t)
inlineinherited

Incorporate some additional data into the RNG state.

Definition at line 84 of file rng.h.

84 {
85 this->add_entropy(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
86 }
FE_25519 T
Definition ge.cpp:34

References T.

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

◆ clear()

void Botan::Stateful_RNG::clear ( )
finalvirtualinherited

Clear all internally held values of this RNG

Postcondition
is_seeded() == false if the RNG has an internal state that can be cleared.

Implements Botan::RandomNumberGenerator.

Definition at line 14 of file stateful_rng.cpp.

14 {
15 lock_guard_type<recursive_mutex_type> lock(m_mutex);
16 m_reseed_counter = 0;
17 m_last_pid = 0;
19}
virtual void clear_state()=0
secure_vector< T > lock(const std::vector< T > &in)
Definition secmem.h:70

References Botan::Stateful_RNG::clear_state(), and Botan::lock().

Referenced by ChaCha_RNG(), ChaCha_RNG(), ChaCha_RNG(), ChaCha_RNG(), ChaCha_RNG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), and Botan::Stateful_RNG::initialize_with().

◆ force_reseed()

void Botan::Stateful_RNG::force_reseed ( )
inherited

Mark state as requiring a reseed on next use

Definition at line 21 of file stateful_rng.cpp.

21 {
22 lock_guard_type<recursive_mutex_type> lock(m_mutex);
23 m_reseed_counter = 0;
24}

References Botan::lock().

◆ initialize_with() [1/2]

void Botan::Stateful_RNG::initialize_with ( const uint8_t input[],
size_t length )
inlineinherited

Definition at line 67 of file stateful_rng.h.

67{ this->initialize_with(std::span(input, length)); }
void initialize_with(std::span< const uint8_t > input)

References Botan::Stateful_RNG::initialize_with().

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

◆ initialize_with() [2/2]

void Botan::Stateful_RNG::initialize_with ( std::span< const uint8_t > input)
inherited

Consume this input and mark the RNG as initialized regardless of the length of the input or the current seeded state of the RNG.

Definition at line 31 of file stateful_rng.cpp.

31 {
32 lock_guard_type<recursive_mutex_type> lock(m_mutex);
33
34 clear();
35 add_entropy(input);
36}

References Botan::RandomNumberGenerator::add_entropy(), Botan::Stateful_RNG::clear(), and Botan::lock().

◆ is_seeded()

bool Botan::Stateful_RNG::is_seeded ( ) const
finalvirtualinherited

Check whether this RNG is seeded.

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

Implements Botan::RandomNumberGenerator.

Definition at line 26 of file stateful_rng.cpp.

26 {
27 lock_guard_type<recursive_mutex_type> lock(m_mutex);
28 return m_reseed_counter > 0;
29}

References Botan::lock().

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

◆ max_number_of_bytes_per_request()

size_t Botan::ChaCha_RNG::max_number_of_bytes_per_request ( ) const
inlineoverridevirtual

Some DRBGs have a notion of the maximum number of bytes per request. Longer requests (to randomize) will be treated as multiple requests, and may initiate reseeding multiple times, depending on the values of max_number_of_bytes_per_request and reseed_interval(). This function returns zero if the RNG in question does not have such a notion.

Returns
max number of bytes per request (or zero)

Implements Botan::Stateful_RNG.

Definition at line 106 of file chacha_rng.h.

106{ return 0; }

◆ name()

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

Implements Botan::RandomNumberGenerator.

Definition at line 102 of file chacha_rng.h.

102{ return "ChaCha_RNG"; }

◆ 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 217 of file rng.h.

217 {
218 uint8_t b;
219 this->fill_bytes_with_input(std::span(&b, 1), {});
220 return b;
221 }

Referenced by Botan::random_prime().

◆ next_nonzero_byte()

uint8_t Botan::RandomNumberGenerator::next_nonzero_byte ( )
inlineinherited
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 228 of file rng.h.

228 {
229 uint8_t b = this->next_byte();
230 while(b == 0) {
231 b = this->next_byte();
232 }
233 return b;
234 }

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

◆ random_vec() [1/3]

template<concepts::resizable_byte_buffer T = secure_vector<uint8_t>>
requires std::default_initializable<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 205 of file rng.h.

205 {
206 T result;
207 random_vec(result, bytes);
208 return result;
209 }
void random_vec(std::span< uint8_t > v)
Definition rng.h:179

References T.

◆ random_vec() [2/3]

void Botan::RandomNumberGenerator::random_vec ( std::span< uint8_t > v)
inlineinherited

◆ 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 190 of file rng.h.

190 {
191 v.resize(bytes);
192 random_vec(v);
193 }

◆ randomize() [1/2]

void Botan::RandomNumberGenerator::randomize ( std::span< uint8_t > output)
inlineinherited

Randomize a byte array.

May block shortly if e.g. the RNG is not yet initialized or a retry because of insufficient entropy is needed.

Parameters
outputthe byte array to hold the random output.
Exceptions
PRNG_Unseededif the RNG fails because it has not enough entropy
Exceptionif the RNG fails

Definition at line 52 of file rng.h.

52{ this->fill_bytes_with_input(output, {}); }

Referenced by Botan::TLS::Connection_Cipher_State::aead_nonce(), Botan::argon2_generate_pwhash(), botan_system_rng_get(), Botan::CryptoBox::encrypt(), Botan::generate_dsa_primes(), Botan::generate_passhash9(), Botan::Roughtime::Nonce::Nonce(), Botan::random_gf2m(), Botan::McEliece_PublicKey::random_plaintext_element(), Botan::random_prime(), Botan::Sodium::randombytes_buf(), Botan::RandomNumberGenerator::randomize_with_ts_input(), Botan::KeyPair::signature_consistency_check(), Botan::RTSS_Share::split(), and Botan::UUID::UUID().

◆ randomize() [2/2]

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

Definition at line 54 of file rng.h.

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

References Botan::RandomNumberGenerator::randomize().

Referenced by Botan::RandomNumberGenerator::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 104 of file rng.h.

104 {
105 this->fill_bytes_with_input(output, input);
106 }

Referenced by Botan::System_RNG::fill_bytes_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

Definition at line 108 of file rng.h.

108 {
109 this->randomize_with_input(std::span(output, output_len), std::span(input, input_len));
110 }
void randomize_with_input(std::span< uint8_t > output, std::span< const uint8_t > input)
Definition rng.h:104

◆ 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 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.

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 21 of file rng.cpp.

21 {
22 if(this->accepts_input()) {
23 constexpr auto s_hd_clk = sizeof(decltype(OS::get_high_resolution_clock()));
24 constexpr auto s_sys_ts = sizeof(decltype(OS::get_system_timestamp_ns()));
25 constexpr auto s_pid = sizeof(decltype(OS::get_process_id()));
26
27 std::array<uint8_t, s_hd_clk + s_sys_ts + s_pid> additional_input = {0};
28 auto s_additional_input = std::span(additional_input.begin(), additional_input.end());
29
30 store_le(OS::get_high_resolution_clock(), s_additional_input.data());
31 s_additional_input = s_additional_input.subspan(s_hd_clk);
32
33#if defined(BOTAN_HAS_SYSTEM_RNG)
34 System_RNG system_rng;
35 system_rng.randomize(s_additional_input);
36#else
37 store_le(OS::get_system_timestamp_ns(), s_additional_input.data());
38 s_additional_input = s_additional_input.subspan(s_sys_ts);
39
40 store_le(OS::get_process_id(), s_additional_input.data());
41#endif
42
43 this->fill_bytes_with_input(output, additional_input);
44 } else {
45 this->fill_bytes_with_input(output, {});
46 }
47}
virtual bool accepts_input() const =0
uint64_t BOTAN_TEST_API get_high_resolution_clock()
Definition os_utils.cpp:266
uint64_t BOTAN_TEST_API get_system_timestamp_ns()
Definition os_utils.cpp:316
uint32_t BOTAN_TEST_API get_process_id()
Definition os_utils.cpp:116
RandomNumberGenerator & system_rng()
constexpr void store_le(T in, OutR &&out_range)
Definition loadstor.h:383

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

◆ randomize_with_ts_input() [2/2]

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

Definition at line 128 of file rng.h.

128 {
129 this->randomize_with_ts_input(std::span(output, output_len));
130 }
void randomize_with_ts_input(std::span< uint8_t > output)
Definition rng.cpp:21

◆ reseed()

size_t Botan::Stateful_RNG::reseed ( Entropy_Sources & srcs,
size_t poll_bits = BOTAN_RNG_RESEED_POLL_BITS,
std::chrono::milliseconds poll_timeout = BOTAN_RNG_RESEED_DEFAULT_TIMEOUT )
overridevirtualinherited

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 77 of file stateful_rng.cpp.

77 {
78 lock_guard_type<recursive_mutex_type> lock(m_mutex);
79
80 const size_t bits_collected = RandomNumberGenerator::reseed(srcs, poll_bits, poll_timeout);
81
82 if(bits_collected >= security_level()) {
83 reset_reseed_counter();
84 }
85
86 return bits_collected;
87}
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)
Definition rng.cpp:49
virtual size_t security_level() const =0

References Botan::lock(), Botan::RandomNumberGenerator::reseed(), and Botan::Stateful_RNG::security_level().

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

◆ reseed_check()

void Botan::Stateful_RNG::reseed_check ( )
protectedinherited

Definition at line 104 of file stateful_rng.cpp.

104 {
105 // Lock is held whenever this function is called
106
107 const uint32_t cur_pid = OS::get_process_id();
108
109 const bool fork_detected = (m_last_pid > 0) && (cur_pid != m_last_pid);
110
111 if(is_seeded() == false || fork_detected || (m_reseed_interval > 0 && m_reseed_counter >= m_reseed_interval)) {
112 m_reseed_counter = 0;
113 m_last_pid = cur_pid;
114
115 if(m_underlying_rng) {
116 reseed_from_rng(*m_underlying_rng, security_level());
117 }
118
119 if(m_entropy_sources) {
120 reseed(*m_entropy_sources, security_level());
121 }
122
123 if(!is_seeded()) {
124 if(fork_detected) {
125 throw Invalid_State("Detected use of fork but cannot reseed DRBG");
126 } else {
127 throw PRNG_Unseeded(name());
128 }
129 }
130 } else {
131 BOTAN_ASSERT(m_reseed_counter != 0, "RNG is seeded");
132 m_reseed_counter += 1;
133 }
134}
#define BOTAN_ASSERT(expr, assertion_made)
Definition assert.h:50
virtual std::string name() const =0
bool is_seeded() const final
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) override
void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS) final

References BOTAN_ASSERT, Botan::OS::get_process_id(), Botan::Stateful_RNG::is_seeded(), Botan::RandomNumberGenerator::name(), Botan::Stateful_RNG::reseed(), Botan::Stateful_RNG::reseed_from_rng(), and Botan::Stateful_RNG::security_level().

◆ reseed_from_rng()

void Botan::Stateful_RNG::reseed_from_rng ( RandomNumberGenerator & rng,
size_t poll_bits = BOTAN_RNG_RESEED_POLL_BITS )
finalvirtualinherited

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 from Botan::RandomNumberGenerator.

Definition at line 89 of file stateful_rng.cpp.

89 {
90 lock_guard_type<recursive_mutex_type> lock(m_mutex);
91
93
94 if(poll_bits >= security_level()) {
95 reset_reseed_counter();
96 }
97}
virtual void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS)
Definition rng.cpp:57

References Botan::lock(), Botan::RandomNumberGenerator::reseed_from_rng(), and Botan::Stateful_RNG::security_level().

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

◆ reseed_interval()

size_t Botan::Stateful_RNG::reseed_interval ( ) const
inlineinherited

Definition at line 106 of file stateful_rng.h.

106{ return m_reseed_interval; }

Referenced by Botan::HMAC_DRBG::HMAC_DRBG(), Botan::HMAC_DRBG::HMAC_DRBG(), and Botan::HMAC_DRBG::HMAC_DRBG().

◆ security_level()

size_t Botan::ChaCha_RNG::security_level ( ) const
overridevirtual
Returns
intended security level of this DRBG

Implements Botan::Stateful_RNG.

Definition at line 70 of file chacha_rng.cpp.

70 {
71 return 256;
72}

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