Botan::Entropy_Sources Class Reference

#include <entropy_src.h>

Public Member Functions
void	add_source (std::unique_ptr< Entropy_Source > src)
std::vector< std::string >	enabled_sources () const
	Entropy_Sources ()=default
	Entropy_Sources (const Entropy_Sources &other)=delete
	Entropy_Sources (const std::vector< std::string > &sources)
	Entropy_Sources (Entropy_Sources &&other)=delete
Entropy_Sources &	operator= (const Entropy_Sources &other)=delete
Entropy_Sources &	operator= (Entropy_Sources &&other)=delete
size_t	poll (RandomNumberGenerator &rng, size_t bits)
size_t	poll (RandomNumberGenerator &rng, size_t bits, std::chrono::milliseconds timeout)
size_t	poll_just (RandomNumberGenerator &rng, std::string_view src)
	~Entropy_Sources ()=default

Static Public Member Functions
static Entropy_Sources &	global_sources ()

Detailed Description

A collection of entropy sources which can be polled together

Definition at line 68 of file entropy_src.h.

Constructor & Destructor Documentation

Entropy_Sources() [1/4]

Botan::Entropy_Sources::Entropy_Sources ( )

default

Create an empty collection of entropy sources

References Entropy_Sources().

Referenced by Entropy_Sources(), Entropy_Sources(), Entropy_Sources(), global_sources(), operator=(), and operator=().

Entropy_Sources() [2/4]

Botan::Entropy_Sources::Entropy_Sources ( const std::vector< std::string > & sources )

explicit

Create a collection containing the named entropy sources

Parameters

sources

the names of the sources to enable

Definition at line 214 of file entropy_srcs.cpp.

                                                                    {
   for(auto&& src_name : sources) {
      add_source(Entropy_Source::create(src_name));
   }
}

References add_source(), and Botan::Entropy_Source::create().

Entropy_Sources() [3/4]

Botan::Entropy_Sources::Entropy_Sources ( const Entropy_Sources & other )

delete

References Entropy_Sources().

Entropy_Sources() [4/4]

Botan::Entropy_Sources::Entropy_Sources ( Entropy_Sources && other )

delete

References Entropy_Sources().

~Entropy_Sources()

Botan::Entropy_Sources::~Entropy_Sources ( )

default

Member Function Documentation

add_source()

void Botan::Entropy_Sources::add_source

(

std::unique_ptr< Entropy_Source >

src

)

Add an entropy source to this collection

Parameters

src	the source to add

Definition at line 154 of file entropy_srcs.cpp.

                                                                  {
   if(src) {
      m_srcs.push_back(std::move(src));
   }
}

Referenced by Entropy_Sources().

enabled_sources()

std::vector< std::string > Botan::Entropy_Sources::enabled_sources

(

)

const

List the entropy sources in this collection

Returns

the names of the enabled sources

Definition at line 160 of file entropy_srcs.cpp.

                                                            {
   std::vector<std::string> sources;
   sources.reserve(m_srcs.size());
   for(const auto& src : m_srcs) {
      sources.push_back(src->name());
   }
   return sources;
}

global_sources()

Entropy_Sources & Botan::Entropy_Sources::global_sources ( )

static

Access the process-wide set of entropy sources used by default

Warning

This object is not synchronized. For general usage (eg polling) this is fine. However if you use global_sources().add_source() concurrently with a poll, likely a race leading to memory corruption will occur; only add a new entropy source at the start of main before RNG objects are created.

Definition at line 220 of file entropy_srcs.cpp.

                                                 {
   static Entropy_Sources global_entropy_sources({"rdseed", "hwrng", "getentropy", "system_rng", "system_stats"});
 
   return global_entropy_sources;
}

References Entropy_Sources().

Referenced by Botan::AutoSeeded_RNG::AutoSeeded_RNG().

operator=() [1/2]

Entropy_Sources & Botan::Entropy_Sources::operator= ( const Entropy_Sources & other )

delete

References Entropy_Sources().

operator=() [2/2]

Entropy_Sources & Botan::Entropy_Sources::operator= ( Entropy_Sources && other )

delete

References Entropy_Sources().

poll() [1/2]

size_t Botan::Entropy_Sources::poll	(	RandomNumberGenerator &	rng,
		size_t	bits )

Poll all sources to collect bits of entropy. Entropy collection is aborted as soon as the requested number of bits are obtained or the timeout runs out.

Returns

the number of bits collected from the entropy sources

Definition at line 190 of file entropy_srcs.cpp.

                                                                         {
   size_t bits_collected = 0;
 
   for(auto& src : m_srcs) {
      bits_collected += src->poll(rng);
 
      if(bits_collected >= poll_bits) {
         break;
      }
   }
 
   return bits_collected;
}

poll() [2/2]

size_t Botan::Entropy_Sources::poll	(	RandomNumberGenerator &	rng,
		size_t	bits,
		std::chrono::milliseconds	timeout )

Poll all sources to collect bits of entropy with a timeout. Entropy collection is aborted as soon as either the requested number of bits are obtained or the timeout runs out. If the target system does not provide a clock, the timeout is ignored.

Note that the timeout is cooperative. If the poll() method of an entropy source blocks forever, this invocation will potentially also block.

Returns

the number of bits collected from the entropy sources

TODO(Botan4) remove this variant, and the <chrono> include above

Definition at line 169 of file entropy_srcs.cpp.

                                                                                                        {
#if defined(BOTAN_TARGET_OS_HAS_SYSTEM_CLOCK)
   typedef std::chrono::system_clock clock;
   auto timeout_expired = [to = clock::now() + timeout] { return clock::now() > to; };
#else
   auto timeout_expired = [] { return false; };
#endif
 
   size_t bits_collected = 0;
 
   for(auto& src : m_srcs) {
      bits_collected += src->poll(rng);
 
      if(bits_collected >= poll_bits || timeout_expired()) {
         break;
      }
   }
 
   return bits_collected;
}

Referenced by Botan::RandomNumberGenerator::reseed_from_sources().

poll_just()

size_t Botan::Entropy_Sources::poll_just	(	RandomNumberGenerator &	rng,
		std::string_view	src )

Poll just a single named source. Ordinally only used for testing

Definition at line 204 of file entropy_srcs.cpp.

                                                                                    {
   for(auto& src : m_srcs) {
      if(src->name() == the_src) {
         return src->poll(rng);
      }
   }
 
   return 0;
}

---

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

• src/lib/entropy/entropy_src.h
• src/lib/entropy/entropy_srcs.cpp