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Botan::HMAC_DRBG Class Referencefinal

`#include <hmac_drbg.h>`

Inheritance diagram for Botan::HMAC_DRBG:

## Public Member Functions
void | add_entropy (const uint8_t input[], size_t input_len) override
template<typename T >
void | add_entropy_T (const T &t)
void | clear () override
void | force_reseed ()
| HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf)
| HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf, RandomNumberGenerator &underlying_rng, size_t reseed_interval=BOTAN_RNG_DEFAULT_RESEED_INTERVAL, size_t max_number_of_bytes_per_request=64 *1024)
| HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf, Entropy_Sources &entropy_sources, size_t reseed_interval=BOTAN_RNG_DEFAULT_RESEED_INTERVAL, size_t max_number_of_bytes_per_request=64 *1024)
| HMAC_DRBG (std::unique_ptr< MessageAuthenticationCode > prf, RandomNumberGenerator &underlying_rng, Entropy_Sources &entropy_sources, size_t reseed_interval=BOTAN_RNG_DEFAULT_RESEED_INTERVAL, size_t max_number_of_bytes_per_request=64 *1024)
| HMAC_DRBG (const std::string &hmac_hash)
void | initialize_with (const uint8_t input[], size_t length)
bool | is_seeded () const overridefinal
std::string | name () const override
uint8_t | next_byte ()
uint8_t | next_nonzero_byte ()
secure_vector< uint8_t > | random_vec (size_t bytes)
void | randomize (uint8_t output[], size_t output_len) override
void | randomize_with_input (uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len) override
void | randomize_with_ts_input (uint8_t output[], size_t output_len) overridefinal
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) overridefinal
size_t | security_level () const override

## Static Public Member Functions
static RandomNumberGenerator * | make_rng ()

## Protected Member Functions
uint32_t | last_pid () const
void | reseed_check ()

## Protected Attributes
size_t | m_reseed_counter = 0

## Detailed Description

HMAC_DRBG from NIST SP800-90A

Definition at line 21 of file hmac_drbg.h.

## Constructor & Destructor Documentation

Botan::HMAC_DRBG::HMAC_DRBG | ( | std::unique_ptr< MessageAuthenticationCode > | prf | ) |

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

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 68 of file hmac_drbg.cpp.

References BOTAN_ASSERT_NONNULL, and clear().

68 :
69 Stateful_RNG(),
70 m_mac(std::move(prf)),
71 m_max_number_of_bytes_per_request(64*1024)
72 {
73 BOTAN_ASSERT_NONNULL(m_mac);
74 clear();
75 }
BOTAN_ASSERT_NONNULL
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:79
Botan::Stateful_RNG::Stateful_RNG
Stateful_RNG()
Definition: stateful_rng.h:67
Botan::HMAC_DRBG::clear
void clear() override
Definition: hmac_drbg.cpp:77

Botan::HMAC_DRBG::HMAC_DRBG | ( | std::unique_ptr< MessageAuthenticationCode > | prf,
|  | RandomNumberGenerator & | underlying_rng,
|  | size_t | reseed_interval = `BOTAN_RNG_DEFAULT_RESEED_INTERVAL`,
|  | size_t | max_number_of_bytes_per_request = `64 * 1024`
| ) |  |

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

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

Parameters

  prf | MAC to use as a PRF
  underlying_rng | is a reference to some RNG which will be used to perform the periodic reseeding
  reseed_interval | specifies a limit of how many times the RNG will be called before automatic reseeding is performed
  max_number_of_bytes_per_request | requests that are in size higher than max_number_of_bytes_per_request are treated as if multiple single requests of max_number_of_bytes_per_request size had been made. In theory SP 800-90A requires that we reject any request for a DRBG output longer than max_number_of_bytes_per_request. To avoid inconveniencing the caller who wants an output larger than max_number_of_bytes_per_request, instead treat these requests as if multiple requests of max_number_of_bytes_per_request size had been made. NIST requires for HMAC_DRBG that every implementation set a value no more than 2**19 bits (or 64 KiB). Together with `reseed_interval` = 1 you can enforce that for example every 512 bit automatic reseeding occurs.

Definition at line 13 of file hmac_drbg.cpp.

References BOTAN_ASSERT_NONNULL, and clear().

16 :
17 Stateful_RNG(underlying_rng, reseed_interval),
18 m_mac(std::move(prf)),
19 m_max_number_of_bytes_per_request(max_number_of_bytes_per_request)
20 {
21 BOTAN_ASSERT_NONNULL(m_mac);
22
23 if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024)
24 {
25 throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request");
26 }
27
28 clear();
29 }
BOTAN_ASSERT_NONNULL
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:79
Botan::Stateful_RNG::Stateful_RNG
Stateful_RNG()
Definition: stateful_rng.h:67
Botan::HMAC_DRBG::clear
void clear() override
Definition: hmac_drbg.cpp:77

Botan::HMAC_DRBG::HMAC_DRBG | ( | std::unique_ptr< MessageAuthenticationCode > | prf,
|  | Entropy_Sources & | entropy_sources,
|  | size_t | reseed_interval = `BOTAN_RNG_DEFAULT_RESEED_INTERVAL`,
|  | size_t | max_number_of_bytes_per_request = `64 * 1024`
| ) |  |

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

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

Parameters

  prf | MAC to use as a PRF
  entropy_sources | will be polled to perform reseeding periodically
  reseed_interval | specifies a limit of how many times the RNG will be called before automatic reseeding is performed.
  max_number_of_bytes_per_request | requests that are in size higher than max_number_of_bytes_per_request are treated as if multiple single requests of max_number_of_bytes_per_request size had been made. In theory SP 800-90A requires that we reject any request for a DRBG output longer than max_number_of_bytes_per_request. To avoid inconveniencing the caller who wants an output larger than max_number_of_bytes_per_request, instead treat these requests as if multiple requests of max_number_of_bytes_per_request size had been made. NIST requires for HMAC_DRBG that every implementation set a value no more than 2**19 bits (or 64 KiB). Together with `reseed_interval` = 1 you can enforce that for example every 512 bit automatic reseeding occurs.

Definition at line 50 of file hmac_drbg.cpp.

References BOTAN_ASSERT_NONNULL, and clear().

53 :
54 Stateful_RNG(entropy_sources, reseed_interval),
55 m_mac(std::move(prf)),
56 m_max_number_of_bytes_per_request(max_number_of_bytes_per_request)
57 {
58 BOTAN_ASSERT_NONNULL(m_mac);
59
60 if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024)
61 {
62 throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request");
63 }
64
65 clear();
66 }
BOTAN_ASSERT_NONNULL
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:79
Botan::Stateful_RNG::Stateful_RNG
Stateful_RNG()
Definition: stateful_rng.h:67
Botan::HMAC_DRBG::clear
void clear() override
Definition: hmac_drbg.cpp:77

Botan::HMAC_DRBG::HMAC_DRBG | ( | std::unique_ptr< MessageAuthenticationCode > | prf,
|  | RandomNumberGenerator & | underlying_rng,
|  | Entropy_Sources & | entropy_sources,
|  | size_t | reseed_interval = `BOTAN_RNG_DEFAULT_RESEED_INTERVAL`,
|  | size_t | max_number_of_bytes_per_request = `64 * 1024`
| ) |  |

Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)

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

Parameters

  prf | MAC to use as a PRF
  underlying_rng | is a reference to some RNG which will be used to perform the periodic reseeding
  entropy_sources | will be polled to perform reseeding periodically
  reseed_interval | specifies a limit of how many times the RNG will be called before automatic reseeding is performed.
  max_number_of_bytes_per_request | requests that are in size higher than max_number_of_bytes_per_request are treated as if multiple single requests of max_number_of_bytes_per_request size had been made. In theory SP 800-90A requires that we reject any request for a DRBG output longer than max_number_of_bytes_per_request. To avoid inconveniencing the caller who wants an output larger than max_number_of_bytes_per_request, instead treat these requests as if multiple requests of max_number_of_bytes_per_request size had been made. NIST requires for HMAC_DRBG that every implementation set a value no more than 2**19 bits (or 64 KiB). Together with `reseed_interval` = 1 you can enforce that for example every 512 bit automatic reseeding occurs.

Definition at line 31 of file hmac_drbg.cpp.

References BOTAN_ASSERT_NONNULL, and clear().

35 :
36 Stateful_RNG(underlying_rng, entropy_sources, reseed_interval),
37 m_mac(std::move(prf)),
38 m_max_number_of_bytes_per_request(max_number_of_bytes_per_request)
39 {
40 BOTAN_ASSERT_NONNULL(m_mac);
41
42 if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024)
43 {
44 throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request");
45 }
46
47 clear();
48 }
BOTAN_ASSERT_NONNULL
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:79
Botan::Stateful_RNG::Stateful_RNG
Stateful_RNG()
Definition: stateful_rng.h:67
Botan::HMAC_DRBG::clear
void clear() override
Definition: hmac_drbg.cpp:77

Botan::HMAC_DRBG::HMAC_DRBG | ( | const std::string & | hmac_hash | ) |
| inline

Constructor taking a string for the hash

Definition at line 125 of file hmac_drbg.h.

125 :
126 Stateful_RNG(),
127 m_mac(MessageAuthenticationCode::create_or_throw("HMAC(" + hmac_hash + ")")),
128 m_max_number_of_bytes_per_request(64 * 1024)
129 {
130 clear();
131 }
Botan::MessageAuthenticationCode::create_or_throw
static std::unique_ptr< MessageAuthenticationCode > create_or_throw(const std::string &algo_spec, const std::string &provider="")
Definition: mac.cpp:138
Botan::Stateful_RNG::Stateful_RNG
Stateful_RNG()
Definition: stateful_rng.h:67
Botan::HMAC_DRBG::clear
void clear() override
Definition: hmac_drbg.cpp:77

## Member Function Documentation

void Botan::HMAC_DRBG::add_entropy | ( | const uint8_t | input[],
|  | size_t | length
| ) |  |
| override 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

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

Implements Botan::RandomNumberGenerator.

Definition at line 158 of file hmac_drbg.cpp.

References Botan::Stateful_RNG::m_reseed_counter, and security_level().

159 {
160 update(input, input_len);
161
162 if(8*input_len >= security_level())
163 {
164 m_reseed_counter = 1;
165 }
166 }
Botan::HMAC_DRBG::security_level
size_t security_level() const override
Definition: hmac_drbg.cpp:168
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132
template<typename T >

void Botan::RandomNumberGenerator::add_entropy_T | ( | const T & | t | ) |
| inline inherited

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 }
Botan::RandomNumberGenerator::add_entropy
virtual void add_entropy(const uint8_t input[], size_t length)=0

void Botan::HMAC_DRBG::clear | ( |  | ) |
| override virtual

Clear all internally held values of this RNG

Postcondition
  is_seeded() == false

Implements Botan::RandomNumberGenerator.

Definition at line 77 of file hmac_drbg.cpp.

References Botan::Stateful_RNG::clear().

Referenced by HMAC_DRBG().

78 {
79 Stateful_RNG::clear();
80
81 m_V.resize(m_mac->output_length());
82 for(size_t i = 0; i != m_V.size(); ++i)
83 m_V[i] = 0x01;
84 m_mac->set_key(std::vector<uint8_t>(m_mac->output_length(), 0x00));
85 }
Botan::Stateful_RNG::clear
void clear() override
Definition: stateful_rng.cpp:13

void Botan::Stateful_RNG::force_reseed | ( |  | ) |
| inherited

Mark state as requiring a reseed on next use

Definition at line 19 of file stateful_rng.cpp.

References Botan::Stateful_RNG::m_reseed_counter.

20 {
21 m_reseed_counter = 0;
22 }
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132

void Botan::Stateful_RNG::initialize_with | ( | const uint8_t | input[],
|  | size_t | length
| ) |  |
| 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 29 of file stateful_rng.cpp.

References Botan::RandomNumberGenerator::add_entropy(), Botan::Stateful_RNG::m_reseed_counter, and Botan::Stateful_RNG::security_level().

30 {
31 add_entropy(input, len);
32
33 if(8*len >= security_level())
34 {
35 m_reseed_counter = 1;
36 }
37 }
Botan::RandomNumberGenerator::add_entropy
virtual void add_entropy(const uint8_t input[], size_t length)=0
Botan::Stateful_RNG::security_level
virtual size_t security_level() const =0
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132

bool Botan::Stateful_RNG::is_seeded | ( |  | ) | const
| final override virtual inherited

Check whether this RNG is seeded.

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

Implements Botan::RandomNumberGenerator.

Definition at line 24 of file stateful_rng.cpp.

References Botan::Stateful_RNG::m_reseed_counter.

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

25 {
26 return m_reseed_counter > 0;
27 }
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132

uint32_t Botan::Stateful_RNG::last_pid | ( |  | ) | const
| inline protected inherited

Definition at line 114 of file stateful_rng.h.

114 { return m_last_pid; }

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

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 }

std::string Botan::HMAC_DRBG::name | ( |  | ) | const
| override virtual

Returns
  the name of this RNG type

Implements Botan::RandomNumberGenerator.

Definition at line 87 of file hmac_drbg.cpp.

88 {
89 return "HMAC_DRBG(" + m_mac->name() + ")";
90 }

uint8_t Botan::RandomNumberGenerator::next_byte | ( |  | ) |
| inline inherited

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 uint8_t b;
147 this->randomize(&b, 1);
148 return b;
149 }
Botan::RandomNumberGenerator::randomize
virtual void randomize(uint8_t output[], size_t length)=0

uint8_t Botan::RandomNumberGenerator::next_nonzero_byte | ( |  | ) |
| inline inherited

Returns
  a random byte that is greater than zero

Definition at line 154 of file rng.h.

155 {
156 uint8_t b = this->next_byte();
157 while(b == 0)
158 b = this->next_byte();
159 return b;
160 }
Botan::RandomNumberGenerator::next_byte
uint8_t next_byte()
Definition: rng.h:144

secure_vector<uint8_t> Botan::RandomNumberGenerator::random_vec | ( | size_t | bytes | ) |
| inline inherited

Return a random vector

Parameters

  bytes | number of bytes in the result

Returns
  randomized vector of length bytes

Definition at line 133 of file rng.h.

Referenced by Botan::CECPQ1_accept(), Botan::CECPQ1_offer(), Botan::TLS::Client_Key_Exchange::Client_Key_Exchange(), Botan::Curve25519_PrivateKey::Curve25519_PrivateKey(), Botan::PK_Decryptor::decrypt_or_random(), Botan::TLS::Session::encrypt(), Botan::KeyPair::encryption_consistency_check(), Botan::generate_bcrypt(), Botan::mceies_encrypt(), Botan::OctetString::OctetString(), Botan::BigInt::randomize(), Botan::TLS::Session_Manager_In_Memory::remove_all(), and Botan::TLS::Session_Manager_SQL::Session_Manager_SQL().

134 {
135 secure_vector<uint8_t> output(bytes);
136 this->randomize(output.data(), output.size());
137 return output;
138 }
Botan::RandomNumberGenerator::randomize
virtual void randomize(uint8_t output[], size_t length)=0

void Botan::HMAC_DRBG::randomize | ( | uint8_t | output[],
|  | size_t | length
| ) |  |
| override virtual

Randomize a byte array.

Parameters

  output | the byte array to hold the random output.
  length | the length of the byte array output in bytes.

Implements Botan::RandomNumberGenerator.

Definition at line 92 of file hmac_drbg.cpp.

References randomize_with_input().

93 {
94 randomize_with_input(output, output_len, nullptr, 0);
95 }
Botan::HMAC_DRBG::randomize_with_input
void randomize_with_input(uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len) override
Definition: hmac_drbg.cpp:101

void Botan::HMAC_DRBG::randomize_with_input | ( | uint8_t | output[],
|  | size_t | output_len,
|  | const uint8_t | input[],
|  | size_t | input_len
| ) |  |
| override 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

  output | buffer to hold the random output
  output_len | size of the output buffer in bytes
  input | entropy buffer to incorporate
  input_len | size of the input buffer in bytes

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 101 of file hmac_drbg.cpp.

References Botan::copy_mem(), Botan::CT::min(), and Botan::Stateful_RNG::reseed_check().

Referenced by randomize().

103 {
104 while(output_len > 0)
105 {
106 size_t this_req = std::min(m_max_number_of_bytes_per_request, output_len);
107 output_len -= this_req;
108
109 reseed_check();
110
111 if(input_len > 0)
112 {
113 update(input, input_len);
114 }
115
116 while(this_req)
117 {
118 const size_t to_copy = std::min(this_req, m_V.size());
119 m_mac->update(m_V.data(), m_V.size());
120 m_mac->final(m_V.data());
121 copy_mem(output, m_V.data(), to_copy);
122
123 output += to_copy;
124 this_req -= to_copy;
125 }
126
127 update(input, input_len);
128 }
129
130 }
Botan::copy_mem
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:68
Botan::Stateful_RNG::reseed_check
void reseed_check()
Definition: stateful_rng.cpp:74
Botan::CT::min
T min(T a, T b)
Definition: ct_utils.h:180

void Botan::Stateful_RNG::randomize_with_ts_input | ( | uint8_t | output[],
|  | size_t | output_len
| ) |  |
| final override virtual inherited

Overrides default implementation and also includes the current process ID and the reseed counter.

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 39 of file stateful_rng.cpp.

References Botan::OS::get_high_resolution_clock(), Botan::OS::get_system_timestamp_ns(), Botan::Stateful_RNG::m_reseed_counter, Botan::RandomNumberGenerator::randomize_with_input(), and Botan::store_le().

40 {
41 uint8_t additional_input[24] = { 0 };
42 store_le(OS::get_system_timestamp_ns(), additional_input);
43 store_le(OS::get_high_resolution_clock(), additional_input + 8);
44 store_le(m_last_pid, additional_input + 16);
45 store_le(static_cast<uint32_t>(m_reseed_counter), additional_input + 20);
46
47 randomize_with_input(output, output_len, additional_input, sizeof(additional_input));
48 }
Botan::RandomNumberGenerator::randomize_with_input
virtual void randomize_with_input(uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)
Definition: rng.cpp:30
Botan::OS::get_system_timestamp_ns
uint64_t BOTAN_DLL get_system_timestamp_ns()
Definition: os_utils.cpp:157
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132
Botan::store_le
void store_le(uint16_t in, uint8_t out[2])
Definition: loadstor.h:457
Botan::OS::get_high_resolution_clock
uint64_t BOTAN_DLL get_high_resolution_clock()
Definition: os_utils.cpp:109

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`
| ) |  |
| override virtual inherited

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 50 of file stateful_rng.cpp.

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

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

53 {
54 size_t bits_collected = RandomNumberGenerator::reseed(srcs, poll_bits, poll_timeout);
55
56 if(bits_collected >= security_level())
57 {
58 m_reseed_counter = 1;
59 }
60
61 return bits_collected;
62 }
Botan::Stateful_RNG::security_level
virtual size_t security_level() const =0
Botan::RandomNumberGenerator::reseed
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:37
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132

void Botan::Stateful_RNG::reseed_check | ( |  | ) |
| protected inherited

Called with lock held

Definition at line 74 of file stateful_rng.cpp.

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

Referenced by randomize_with_input().

75 {
76 const uint32_t cur_pid = OS::get_process_id();
77
78 const bool fork_detected = (m_last_pid > 0) && (cur_pid != m_last_pid);
79
80 if(is_seeded() == false ||
81 fork_detected ||
82 (m_reseed_interval > 0 && m_reseed_counter >= m_reseed_interval))
83 {
84 m_reseed_counter = 0;
85 m_last_pid = cur_pid;
86
87 if(m_underlying_rng)
88 {
89 reseed_from_rng(*m_underlying_rng, security_level());
90 }
91
92 if(m_entropy_sources)
93 {
94 reseed(*m_entropy_sources, security_level());
95 }
96
97 if(!is_seeded())
98 {
99 if(fork_detected)
100 throw Exception("Detected use of fork but cannot reseed DRBG");
101 else
102 throw PRNG_Unseeded(name());
103 }
104 }
105 else
106 {
107 BOTAN_ASSERT(m_reseed_counter != 0, "RNG is seeded");
108 m_reseed_counter += 1;
109 }
110 }
Botan::OS::get_process_id
uint32_t BOTAN_DLL get_process_id()
Definition: os_utils.cpp:31
Botan::Stateful_RNG::security_level
virtual size_t security_level() const =0
BOTAN_ASSERT
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:27
Botan::Stateful_RNG::reseed_from_rng
void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS) overridefinal
Definition: stateful_rng.cpp:64
Botan::RandomNumberGenerator::name
virtual std::string name() const =0
Botan::Stateful_RNG::is_seeded
bool is_seeded() const overridefinal
Definition: stateful_rng.cpp:24
Botan::Stateful_RNG::reseed
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
Definition: stateful_rng.cpp:50
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132

void Botan::Stateful_RNG::reseed_from_rng | ( | RandomNumberGenerator & | rng,
|  | size_t | poll_bits = `BOTAN_RNG_RESEED_POLL_BITS`
| ) |  |
| final override virtual inherited

Reseed by reading specified bits from the RNG

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 64 of file stateful_rng.cpp.

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

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

65 {
66 RandomNumberGenerator::reseed_from_rng(rng, poll_bits);
67
68 if(poll_bits >= security_level())
69 {
70 m_reseed_counter = 1;
71 }
72 }
Botan::Stateful_RNG::security_level
virtual size_t security_level() const =0
Botan::RandomNumberGenerator::reseed_from_rng
virtual void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS)
Definition: rng.cpp:44
Botan::Stateful_RNG::m_reseed_counter
size_t m_reseed_counter
Definition: stateful_rng.h:132

size_t Botan::HMAC_DRBG::security_level | ( |  | ) | const
| override virtual

Returns
  intended security level of this DRBG

Implements Botan::Stateful_RNG.

Definition at line 168 of file hmac_drbg.cpp.

Referenced by add_entropy().

169 {
170 // security strength of the hash function
171 // for pre-image resistance (see NIST SP 800-57)
172 // SHA-160: 128 bits, SHA-224, SHA-512/224: 192 bits,
173 // SHA-256, SHA-512/256, SHA-384, SHA-512: >= 256 bits
174 // NIST SP 800-90A only supports up to 256 bits though
175 if(m_mac->output_length() < 32)
176 {
177 return (m_mac->output_length() - 4) * 8;
178 }
179 else
180 {
181 return 32 * 8;
182 }
183 }

## Member Data Documentation

size_t Botan::Stateful_RNG::m_reseed_counter = 0
| protected inherited

Definition at line 132 of file stateful_rng.h.

Referenced by add_entropy(), Botan::Stateful_RNG::clear(), Botan::Stateful_RNG::force_reseed(), Botan::Stateful_RNG::initialize_with(), Botan::Stateful_RNG::is_seeded(), Botan::Stateful_RNG::randomize_with_ts_input(), Botan::Stateful_RNG::reseed(), Botan::Stateful_RNG::reseed_check(), and Botan::Stateful_RNG::reseed_from_rng().

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

- src/lib/rng/hmac_drbg/hmac_drbg.h
- src/lib/rng/hmac_drbg/hmac_drbg.cpp