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::Stateful_RNG Class Referenceabstract

#include <stateful_rng.h>

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

Public Member Functions

virtual void add_entropy (const uint8_t input[], size_t length)=0
 
template<typename T >
void add_entropy_T (const T &t)
 
void clear () override
 
void force_reseed ()
 
void initialize_with (const uint8_t input[], size_t length)
 
bool is_seeded () const override final
 
virtual size_t max_number_of_bytes_per_request () const =0
 
virtual std::string name () const =0
 
uint8_t next_byte ()
 
uint8_t next_nonzero_byte ()
 
secure_vector< uint8_t > random_vec (size_t bytes)
 
virtual void randomize (uint8_t output[], size_t length)=0
 
virtual void randomize_with_input (uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)
 
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
 
virtual size_t security_level () const =0
 
 Stateful_RNG (RandomNumberGenerator &rng, Entropy_Sources &entropy_sources, size_t reseed_interval)
 
 Stateful_RNG (RandomNumberGenerator &rng, size_t reseed_interval)
 
 Stateful_RNG (Entropy_Sources &entropy_sources, size_t reseed_interval)
 
 Stateful_RNG ()
 

Static Public Member Functions

static RandomNumberGeneratormake_rng ()
 

Protected Member Functions

void reseed_check ()
 
void reset_reseed_counter ()
 

Detailed Description

Inherited by RNGs which maintain in-process state, like HMAC_DRBG. On Unix these RNGs are vulnerable to problems with fork, where the RNG state is duplicated, and the parent and child process RNGs will produce identical output until one of them reseeds. Stateful_RNG reseeds itself whenever a fork is detected, or after a set number of bytes have been output.

Not implemented by RNGs which access an external RNG, such as the system PRNG or a hardware RNG.

Definition at line 25 of file stateful_rng.h.

Constructor & Destructor Documentation

◆ Stateful_RNG() [1/4]

Botan::Stateful_RNG::Stateful_RNG ( RandomNumberGenerator rng,
Entropy_Sources entropy_sources,
size_t  reseed_interval 
)
inline
Parameters
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 35 of file stateful_rng.h.

37  :
38  m_underlying_rng(&rng),
39  m_entropy_sources(&entropy_sources),
40  m_reseed_interval(reseed_interval)
41  {}
size_t reseed_interval() const
Definition: stateful_rng.h:118

◆ Stateful_RNG() [2/4]

Botan::Stateful_RNG::Stateful_RNG ( RandomNumberGenerator rng,
size_t  reseed_interval 
)
inline
Parameters
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 49 of file stateful_rng.h.

49  :
50  m_underlying_rng(&rng),
51  m_reseed_interval(reseed_interval)
52  {}
size_t reseed_interval() const
Definition: stateful_rng.h:118

◆ Stateful_RNG() [3/4]

Botan::Stateful_RNG::Stateful_RNG ( Entropy_Sources entropy_sources,
size_t  reseed_interval 
)
inline
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 59 of file stateful_rng.h.

59  :
60  m_entropy_sources(&entropy_sources),
61  m_reseed_interval(reseed_interval)
62  {}
size_t reseed_interval() const
Definition: stateful_rng.h:118

◆ Stateful_RNG() [4/4]

Botan::Stateful_RNG::Stateful_RNG ( )
inline

In this case, automatic reseeding is impossible

Definition at line 67 of file stateful_rng.h.

67 : m_reseed_interval(0) {}

Member Function Documentation

◆ add_entropy()

virtual void Botan::RandomNumberGenerator::add_entropy ( const uint8_t  input[],
size_t  length 
)
pure virtualinherited

Incorporate some additional data into the RNG state. For example adding nonces or timestamps from a peer's protocol message can help hedge against VM state rollback attacks. A few RNG types do not accept any externally provided input, in which case this function is a no-op.

Parameters
inputa byte array containg the entropy to be added
lengththe length of the byte array in

Implemented in Botan::Null_RNG, Botan::HMAC_DRBG, Botan::ChaCha_RNG, Botan::TPM_RNG, Botan::RDRAND_RNG, Botan::AutoSeeded_RNG, and Botan::System_RNG.

Referenced by Botan::System_RNG::add_entropy(), initialize_with(), Botan::Getentropy::poll(), Botan::Intel_Rdrand::poll(), Botan::Darwin_SecRandom::poll(), Botan::Device_EntropySource::poll(), Botan::ProcWalking_EntropySource::poll(), Botan::RandomNumberGenerator::randomize_with_input(), and Botan::RandomNumberGenerator::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 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::Stateful_RNG::clear ( )
overridevirtual

Clear all internally held values of this RNG

Postcondition
is_seeded() == false

Implements Botan::RandomNumberGenerator.

Definition at line 13 of file stateful_rng.cpp.

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

14  {
15  m_reseed_counter = 0;
16  m_last_pid = 0;
17  }

◆ force_reseed()

void Botan::Stateful_RNG::force_reseed ( )

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 
)

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(), reset_reseed_counter(), and 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
finaloverridevirtual

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 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()

virtual size_t Botan::Stateful_RNG::max_number_of_bytes_per_request ( ) const
pure virtual

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)

Implemented in Botan::HMAC_DRBG, and Botan::ChaCha_RNG.

◆ name()

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

◆ 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()

virtual void Botan::RandomNumberGenerator::randomize ( uint8_t  output[],
size_t  length 
)
pure virtualinherited

◆ randomize_with_input()

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

Incorporate entropy into the RNG state then produce output. Some RNG types implement this using a single operation, default calls add_entropy + randomize in sequence.

Use this to further bind the outputs to your current process/protocol state. For instance if generating a new key for use in a session, include a session ID or other such value. See NIST SP 800-90 A, B, C series for more ideas.

Parameters
outputbuffer to hold the random output
output_lensize of the output buffer in bytes
inputentropy buffer to incorporate
input_lensize of the input buffer in bytes

Reimplemented in Botan::HMAC_DRBG, Botan::ChaCha_RNG, and Botan::AutoSeeded_RNG.

Definition at line 31 of file rng.cpp.

References Botan::RandomNumberGenerator::add_entropy(), and Botan::RandomNumberGenerator::randomize().

Referenced by randomize_with_ts_input(), and Botan::RandomNumberGenerator::randomize_with_ts_input().

33  {
34  this->add_entropy(input, input_len);
35  this->randomize(output, output_len);
36  }
virtual void add_entropy(const uint8_t input[], size_t length)=0
virtual void randomize(uint8_t output[], size_t length)=0

◆ randomize_with_ts_input()

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

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 
)
overridevirtual

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(), reset_reseed_counter(), and security_level().

Referenced by 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 ( )
protected

Definition at line 74 of file stateful_rng.cpp.

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

Referenced by Botan::ChaCha_RNG::randomize_with_input(), and Botan::HMAC_DRBG::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 
)
finaloverridevirtual

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(), reset_reseed_counter(), and security_level().

Referenced by 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
inline

Definition at line 118 of file stateful_rng.h.

118 { return m_reseed_interval; }

◆ reset_reseed_counter()

void Botan::Stateful_RNG::reset_reseed_counter ( )
inlineprotected

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(), Botan::HMAC_DRBG::add_entropy(), initialize_with(), reseed(), and reseed_from_rng().

129 { m_reseed_counter = 1; }

◆ security_level()

virtual size_t Botan::Stateful_RNG::security_level ( ) const
pure virtual
Returns
intended security level of this DRBG

Implemented in Botan::HMAC_DRBG, and Botan::ChaCha_RNG.

Referenced by initialize_with(), reseed(), reseed_check(), and reseed_from_rng().


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