Botan  2.19.1
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

bool accepts_input () const overridefinal
 
void add_entropy (const uint8_t input[], size_t input_len) overridefinal
 
template<typename T >
void add_entropy_T (const T &t)
 
void clear () overridefinal
 
void force_reseed ()
 
void initialize_with (const uint8_t input[], size_t length)
 
bool is_seeded () const overridefinal
 
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)
 
template<typename Alloc >
void random_vec (std::vector< uint8_t, Alloc > &v, size_t bytes)
 
void randomize (uint8_t output[], size_t output_len) overridefinal
 
void randomize_with_input (uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len) overridefinal
 
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 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

virtual void clear_state ()=0
 
virtual void generate_output (uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)=0
 
void reseed_check ()
 
virtual void update (const uint8_t input[], size_t input_len)=0
 

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 26 of file stateful_rng.h.

Constructor & Destructor Documentation

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 36 of file stateful_rng.h.

38  :
39  m_underlying_rng(&rng),
40  m_entropy_sources(&entropy_sources),
41  m_reseed_interval(reseed_interval)
42  {}
size_t reseed_interval() const
Definition: stateful_rng.h:128
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 50 of file stateful_rng.h.

50  :
51  m_underlying_rng(&rng),
52  m_reseed_interval(reseed_interval)
53  {}
size_t reseed_interval() const
Definition: stateful_rng.h:128
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 60 of file stateful_rng.h.

60  :
61  m_entropy_sources(&entropy_sources),
62  m_reseed_interval(reseed_interval)
63  {}
size_t reseed_interval() const
Definition: stateful_rng.h:128
Botan::Stateful_RNG::Stateful_RNG ( )
inline

In this case, automatic reseeding is impossible

Definition at line 68 of file stateful_rng.h.

68 : m_reseed_interval(0) {}

Member Function Documentation

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

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 79 of file stateful_rng.h.

79 { return true; }
void Botan::Stateful_RNG::add_entropy ( const uint8_t  input[],
size_t  length 
)
finaloverridevirtual

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 37 of file stateful_rng.cpp.

References security_level(), and update().

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

38  {
39  lock_guard_type<recursive_mutex_type> lock(m_mutex);
40 
41  update(input, input_len);
42 
43  if(8*input_len >= security_level())
44  {
45  reset_reseed_counter();
46  }
47  }
virtual size_t security_level() const =0
virtual void update(const uint8_t input[], size_t input_len)=0
template<typename T >
void Botan::RandomNumberGenerator::add_entropy_T ( const T t)
inlineinherited

Incorporate some additional data into the RNG state.

Definition at line 69 of file rng.h.

References T.

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

70  {
71  static_assert(std::is_standard_layout<T>::value && std::is_trivial<T>::value, "add_entropy_T data must be POD");
72  this->add_entropy(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
73  }
virtual void add_entropy(const uint8_t input[], size_t length)=0
fe T
Definition: ge.cpp:37
void Botan::Stateful_RNG::clear ( )
finaloverridevirtual

Clear all internally held values of this RNG

Postcondition
is_seeded() == false

Implements Botan::RandomNumberGenerator.

Definition at line 17 of file stateful_rng.cpp.

References clear_state().

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

18  {
19  lock_guard_type<recursive_mutex_type> lock(m_mutex);
20  m_reseed_counter = 0;
21  m_last_pid = 0;
22  clear_state();
23  }
virtual void clear_state()=0
virtual void Botan::Stateful_RNG::clear_state ( )
protectedpure virtual

Referenced by clear().

void Botan::Stateful_RNG::force_reseed ( )

Mark state as requiring a reseed on next use

Definition at line 25 of file stateful_rng.cpp.

26  {
27  lock_guard_type<recursive_mutex_type> lock(m_mutex);
28  m_reseed_counter = 0;
29  }
virtual void Botan::Stateful_RNG::generate_output ( uint8_t  output[],
size_t  output_len,
const uint8_t  input[],
size_t  input_len 
)
protectedpure virtual

Referenced by randomize_with_input().

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 49 of file stateful_rng.cpp.

References add_entropy(), and clear().

50  {
51  lock_guard_type<recursive_mutex_type> lock(m_mutex);
52 
53  clear();
54  add_entropy(input, len);
55  }
void add_entropy(const uint8_t input[], size_t input_len) overridefinal
void clear() overridefinal
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 31 of file stateful_rng.cpp.

Referenced by reseed_check().

32  {
33  lock_guard_type<recursive_mutex_type> lock(m_mutex);
34  return m_reseed_counter > 0;
35  }
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 69 of file rng.cpp.

70  {
71 #if defined(BOTAN_HAS_AUTO_SEEDING_RNG)
72  return new AutoSeeded_RNG;
73 #else
74  throw Not_Implemented("make_rng failed, no AutoSeeded_RNG in this build");
75 #endif
76  }
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.

Referenced by randomize_with_input().

virtual std::string Botan::RandomNumberGenerator::name ( ) const
pure virtualinherited
uint8_t Botan::RandomNumberGenerator::next_byte ( )
inlineinherited

Return a random byte

Returns
random byte

Definition at line 161 of file rng.h.

Referenced by Botan::random_prime().

162  {
163  uint8_t b;
164  this->randomize(&b, 1);
165  return b;
166  }
virtual void randomize(uint8_t output[], size_t length)=0
uint8_t Botan::RandomNumberGenerator::next_nonzero_byte ( )
inlineinherited
Returns
a random byte that is greater than zero

Definition at line 171 of file rng.h.

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

172  {
173  uint8_t b = this->next_byte();
174  while(b == 0)
175  b = this->next_byte();
176  return b;
177  }
secure_vector<uint8_t> Botan::RandomNumberGenerator::random_vec ( size_t  bytes)
inlineinherited
template<typename Alloc >
void Botan::RandomNumberGenerator::random_vec ( std::vector< uint8_t, Alloc > &  v,
size_t  bytes 
)
inlineinherited

Definition at line 151 of file rng.h.

152  {
153  v.resize(bytes);
154  this->randomize(v.data(), v.size());
155  }
virtual void randomize(uint8_t output[], size_t length)=0
void Botan::Stateful_RNG::randomize ( uint8_t  output[],
size_t  length 
)
finaloverridevirtual

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 57 of file stateful_rng.cpp.

References randomize_with_input().

58  {
59  randomize_with_input(output, output_len, nullptr, 0);
60  }
void randomize_with_input(uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len) overridefinal
void Botan::Stateful_RNG::randomize_with_input ( uint8_t  output[],
size_t  output_len,
const uint8_t  input[],
size_t  input_len 
)
finaloverridevirtual

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 79 of file stateful_rng.cpp.

References generate_output(), max_number_of_bytes_per_request(), and reseed_check().

Referenced by randomize(), and randomize_with_ts_input().

81  {
82  if(output_len == 0)
83  return;
84 
85  lock_guard_type<recursive_mutex_type> lock(m_mutex);
86 
87  const size_t max_per_request = max_number_of_bytes_per_request();
88 
89  if(max_per_request == 0) // no limit
90  {
91  reseed_check();
92  this->generate_output(output, output_len, input, input_len);
93  }
94  else
95  {
96  while(output_len > 0)
97  {
98  const size_t this_req = std::min(max_per_request, output_len);
99 
100  /*
101  * We split the request into several requests to the underlying DRBG but
102  * pass the input to each invocation. It might be more sensible to only
103  * provide it for the first invocation, however between 2.0 and 2.15
104  * HMAC_DRBG always provided it for all requests so retain that here.
105  */
106 
107  reseed_check();
108  this->generate_output(output, this_req, input, input_len);
109 
110  output += this_req;
111  output_len -= this_req;
112  }
113  }
114  }
virtual void generate_output(uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len)=0
virtual size_t max_number_of_bytes_per_request() const =0
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 62 of file stateful_rng.cpp.

References Botan::OS::get_high_resolution_clock(), Botan::OS::get_process_id(), Botan::OS::get_system_timestamp_ns(), Botan::System_RNG::randomize(), randomize_with_input(), Botan::store_le(), and Botan::system_rng().

63  {
64  uint8_t additional_input[20] = { 0 };
65 
66  store_le(OS::get_high_resolution_clock(), additional_input);
67 
68 #if defined(BOTAN_HAS_SYSTEM_RNG)
69  System_RNG system_rng;
70  system_rng.randomize(additional_input + 8, sizeof(additional_input) - 8);
71 #else
72  store_le(OS::get_system_timestamp_ns(), additional_input + 8);
73  store_le(OS::get_process_id(), additional_input + 16);
74 #endif
75 
76  randomize_with_input(output, output_len, additional_input, sizeof(additional_input));
77  }
RandomNumberGenerator & system_rng()
Definition: system_rng.cpp:283
virtual void randomize(uint8_t output[], size_t length)=0
uint32_t BOTAN_TEST_API get_process_id()
Definition: os_utils.cpp:96
void randomize_with_input(uint8_t output[], size_t output_len, const uint8_t input[], size_t input_len) overridefinal
uint64_t BOTAN_TEST_API get_system_timestamp_ns()
Definition: os_utils.cpp:293
void store_le(uint16_t in, uint8_t out[2])
Definition: loadstor.h:454
uint64_t BOTAN_TEST_API get_high_resolution_clock()
Definition: os_utils.cpp:241
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 116 of file stateful_rng.cpp.

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

Referenced by reseed_check().

119  {
120  lock_guard_type<recursive_mutex_type> lock(m_mutex);
121 
122  const size_t bits_collected = RandomNumberGenerator::reseed(srcs, poll_bits, poll_timeout);
123 
124  if(bits_collected >= security_level())
125  {
126  reset_reseed_counter();
127  }
128 
129  return bits_collected;
130  }
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:45
void Botan::Stateful_RNG::reseed_check ( )
protected

Definition at line 150 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 randomize_with_input().

151  {
152  // Lock is held whenever this function is called
153 
154  const uint32_t cur_pid = OS::get_process_id();
155 
156  const bool fork_detected = (m_last_pid > 0) && (cur_pid != m_last_pid);
157 
158  if(is_seeded() == false ||
159  fork_detected ||
160  (m_reseed_interval > 0 && m_reseed_counter >= m_reseed_interval))
161  {
162  m_reseed_counter = 0;
163  m_last_pid = cur_pid;
164 
165  if(m_underlying_rng)
166  {
167  reseed_from_rng(*m_underlying_rng, security_level());
168  }
169 
170  if(m_entropy_sources)
171  {
172  reseed(*m_entropy_sources, security_level());
173  }
174 
175  if(!is_seeded())
176  {
177  if(fork_detected)
178  throw Invalid_State("Detected use of fork but cannot reseed DRBG");
179  else
180  throw PRNG_Unseeded(name());
181  }
182  }
183  else
184  {
185  BOTAN_ASSERT(m_reseed_counter != 0, "RNG is seeded");
186  m_reseed_counter += 1;
187  }
188  }
uint32_t BOTAN_TEST_API get_process_id()
Definition: os_utils.cpp:96
virtual size_t security_level() const =0
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:55
void reseed_from_rng(RandomNumberGenerator &rng, size_t poll_bits=BOTAN_RNG_RESEED_POLL_BITS) overridefinal
virtual std::string name() const =0
bool is_seeded() const 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 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 132 of file stateful_rng.cpp.

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

Referenced by reseed_check().

133  {
134  lock_guard_type<recursive_mutex_type> lock(m_mutex);
135 
137 
138  if(poll_bits >= security_level())
139  {
140  reset_reseed_counter();
141  }
142  }
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:59
size_t Botan::Stateful_RNG::reseed_interval ( ) const
inline

Definition at line 128 of file stateful_rng.h.

128 { return m_reseed_interval; }
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 add_entropy(), reseed(), reseed_check(), and reseed_from_rng().

virtual void Botan::Stateful_RNG::update ( const uint8_t  input[],
size_t  input_len 
)
protectedpure virtual

Referenced by add_entropy().


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