Botan  2.4.0
Crypto and TLS for C++11
Public Member Functions | Static Public Member Functions | Protected Member Functions | List of all members
Botan::HMAC_DRBG Class Referencefinal

#include <hmac_drbg.h>

Inheritance diagram for Botan::HMAC_DRBG:
Botan::Stateful_RNG Botan::RandomNumberGenerator

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 override 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 ()
 
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) override 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) override final
 
size_t reseed_interval () const
 
size_t security_level () const override
 

Static Public Member Functions

static RandomNumberGeneratormake_rng ()
 

Protected Member Functions

void reseed_check ()
 
void reset_reseed_counter ()
 

Detailed Description

HMAC_DRBG from NIST SP800-90A

Definition at line 21 of file hmac_drbg.h.

Constructor & Destructor Documentation

◆ HMAC_DRBG() [1/5]

Botan::HMAC_DRBG::HMAC_DRBG ( std::unique_ptr< MessageAuthenticationCode prf)
explicit

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  }
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:81
void clear() override
Definition: hmac_drbg.cpp:77

◆ HMAC_DRBG() [2/5]

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
prfMAC to use as a PRF
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
max_number_of_bytes_per_requestrequests 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.

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  }
size_t reseed_interval() const
Definition: stateful_rng.h:118
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:81
size_t max_number_of_bytes_per_request() const override
Definition: hmac_drbg.h:146
void clear() override
Definition: hmac_drbg.cpp:77

◆ HMAC_DRBG() [3/5]

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
prfMAC to use as a PRF
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.
max_number_of_bytes_per_requestrequests 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  }
size_t reseed_interval() const
Definition: stateful_rng.h:118
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:81
size_t max_number_of_bytes_per_request() const override
Definition: hmac_drbg.h:146
void clear() override
Definition: hmac_drbg.cpp:77

◆ HMAC_DRBG() [4/5]

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
prfMAC to use as a PRF
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.
max_number_of_bytes_per_requestrequests 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  }
size_t reseed_interval() const
Definition: stateful_rng.h:118
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:81
size_t max_number_of_bytes_per_request() const override
Definition: hmac_drbg.h:146
void clear() override
Definition: hmac_drbg.cpp:77

◆ HMAC_DRBG() [5/5]

Botan::HMAC_DRBG::HMAC_DRBG ( const std::string &  hmac_hash)
inlineexplicit

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  }
static std::unique_ptr< MessageAuthenticationCode > create_or_throw(const std::string &algo_spec, const std::string &provider="")
Definition: mac.cpp:140
void clear() override
Definition: hmac_drbg.cpp:77

Member Function Documentation

◆ add_entropy()

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

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 158 of file hmac_drbg.cpp.

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

159  {
160  update(input, input_len);
161 
162  if(8*input_len >= security_level())
163  {
165  }
166  }
size_t security_level() const override
Definition: hmac_drbg.cpp:168

◆ 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 59 of file rng.h.

References T.

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

60  {
61  this->add_entropy(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
62  }
virtual void add_entropy(const uint8_t input[], size_t length)=0
fe T
Definition: ge.cpp:37

◆ clear()

void Botan::HMAC_DRBG::clear ( )
overridevirtual

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  {
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  }
void clear() override

◆ force_reseed()

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.

20  {
21  m_reseed_counter = 0;
22  }

◆ initialize_with()

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::reset_reseed_counter(), and Botan::Stateful_RNG::security_level().

30  {
31  add_entropy(input, len);
32 
33  if(8*len >= security_level())
34  {
36  }
37  }
virtual void add_entropy(const uint8_t input[], size_t length)=0
virtual size_t security_level() const =0

◆ is_seeded()

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

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.

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

25  {
26  return m_reseed_counter > 0;
27  }

◆ 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 52 of file rng.cpp.

53  {
54 #if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
55  return new AutoSeeded_RNG;
56 #else
57  throw Exception("make_rng failed, no AutoSeeded_RNG in this build");
58 #endif
59  }

◆ max_number_of_bytes_per_request()

size_t Botan::HMAC_DRBG::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 146 of file hmac_drbg.h.

147  { return m_max_number_of_bytes_per_request; }

◆ name()

std::string Botan::HMAC_DRBG::name ( ) const
overridevirtual
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  }

◆ next_byte()

uint8_t Botan::RandomNumberGenerator::next_byte ( )
inlineinherited

Return a random byte

Returns
random byte

Definition at line 143 of file rng.h.

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

144  {
145  uint8_t b;
146  this->randomize(&b, 1);
147  return b;
148  }
virtual void randomize(uint8_t output[], size_t length)=0

◆ next_nonzero_byte()

uint8_t Botan::RandomNumberGenerator::next_nonzero_byte ( )
inlineinherited
Returns
a random byte that is greater than zero

Definition at line 153 of file rng.h.

154  {
155  uint8_t b = this->next_byte();
156  while(b == 0)
157  b = this->next_byte();
158  return b;
159  }

◆ random_vec()

secure_vector<uint8_t> Botan::RandomNumberGenerator::random_vec ( size_t  bytes)
inlineinherited

◆ randomize()

void Botan::HMAC_DRBG::randomize ( uint8_t  output[],
size_t  length 
)
overridevirtual

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 92 of file hmac_drbg.cpp.

References randomize_with_input().

93  {
94  randomize_with_input(output, output_len, nullptr, 0);
95  }
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

◆ randomize_with_input()

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

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 from Botan::RandomNumberGenerator.

Definition at line 101 of file hmac_drbg.cpp.

References Botan::copy_mem(), 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  }
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:97

◆ randomize_with_ts_input()

void Botan::Stateful_RNG::randomize_with_ts_input ( uint8_t  output[],
size_t  output_len 
)
finaloverridevirtualinherited

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::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  }
virtual void randomize_with_input(uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)
Definition: rng.cpp:31
uint64_t BOTAN_TEST_API get_system_timestamp_ns()
Definition: os_utils.cpp:183
void store_le(uint16_t in, uint8_t out[2])
Definition: loadstor.h:450
uint64_t BOTAN_TEST_API get_high_resolution_clock()
Definition: os_utils.cpp:135

◆ 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 50 of file stateful_rng.cpp.

References Botan::RandomNumberGenerator::reseed(), Botan::Stateful_RNG::reset_reseed_counter(), 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  {
59  }
60 
61  return bits_collected;
62  }
virtual size_t security_level() const =0
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:38

◆ reseed_check()

void Botan::Stateful_RNG::reseed_check ( )
protectedinherited

Definition at line 74 of file stateful_rng.cpp.

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().

Referenced by Botan::ChaCha_RNG::randomize_with_input(), and 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  }
bool is_seeded() const override final
uint32_t BOTAN_TEST_API get_process_id()
Definition: os_utils.cpp:64
virtual size_t security_level() const =0
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:29
virtual std::string name() const =0
void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS) override 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

◆ reseed_from_rng()

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

Reseed by reading specified bits from the RNG

Reimplemented from Botan::RandomNumberGenerator.

Definition at line 64 of file stateful_rng.cpp.

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

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

65  {
67 
68  if(poll_bits >= security_level())
69  {
71  }
72  }
virtual size_t security_level() const =0
virtual void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS)
Definition: rng.cpp:45

◆ reseed_interval()

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

Definition at line 118 of file stateful_rng.h.

118 { return m_reseed_interval; }

◆ reset_reseed_counter()

void Botan::Stateful_RNG::reset_reseed_counter ( )
inlineprotectedinherited

Called by a subclass to notify that a reseed has been successfully performed.

Definition at line 129 of file stateful_rng.h.

Referenced by Botan::ChaCha_RNG::add_entropy(), add_entropy(), Botan::Stateful_RNG::initialize_with(), Botan::Stateful_RNG::reseed(), and Botan::Stateful_RNG::reseed_from_rng().

129 { m_reseed_counter = 1; }

◆ security_level()

size_t Botan::HMAC_DRBG::security_level ( ) const
overridevirtual
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  }

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