ffi_rng.cpp File Reference

#include <botan/ffi.h>
#include <botan/internal/ffi_util.h>
#include <botan/internal/ffi_rng.h>
#include <botan/system_rng.h>
#include <botan/auto_rng.h>
#include <functional>
#include <memory>

Go to the source code of this file.

Functions
int	botan_rng_add_entropy (botan_rng_t rng, const uint8_t *input, size_t len)
int	botan_rng_destroy (botan_rng_t rng)
int	botan_rng_get (botan_rng_t rng, uint8_t *out, size_t out_len)
int	botan_rng_init (botan_rng_t *rng_out, const char *rng_type)
int	botan_rng_init_custom (botan_rng_t *rng_out, const char *rng_name, void *context, int(*get_cb)(void *context, uint8_t *out, size_t out_len), int(*add_entropy_cb)(void *context, const uint8_t input[], size_t length), void(*destroy_cb)(void *context))
int	botan_rng_reseed (botan_rng_t rng, size_t bits)
int	botan_rng_reseed_from_rng (botan_rng_t rng, botan_rng_t source_rng, size_t bits)
int	botan_system_rng_get (uint8_t *out, size_t out_len)

Function Documentation

botan_rng_add_entropy()

int botan_rng_add_entropy	(	botan_rng_t	rng,
		const uint8_t *	entropy,
		size_t	entropy_len
	)

Add some seed material to a random number generator

Parameters

rng	rng object
entropy	the data to add
entropy_len	length of entropy buffer

Returns

0 on success, a negative value on failure

Definition at line 188 of file ffi_rng.cpp.

   {
   return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.add_entropy(input, len); });
   }

References BOTAN_FFI_VISIT.

botan_rng_destroy()

int botan_rng_destroy

(

botan_rng_t

rng

)

Frees all resources of the random number generator object

Parameters

rng	rng object

Returns

0 if success, error if invalid object handle

Definition at line 164 of file ffi_rng.cpp.

   {
   return BOTAN_FFI_CHECKED_DELETE(rng);
   }

References BOTAN_FFI_CHECKED_DELETE.

botan_rng_get()

int botan_rng_get	(	botan_rng_t	rng,
		uint8_t *	out,
		size_t	out_len
	)

Get random bytes from a random number generator

Parameters

rng	rng object
out	output buffer of size out_len
out_len	number of requested bytes

Returns

0 on success, negative on failure

Definition at line 169 of file ffi_rng.cpp.

   {
   return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.randomize(out, out_len); });
   }

References BOTAN_FFI_VISIT.

botan_rng_init()

int botan_rng_init	(	botan_rng_t *	rng,
		const char *	rng_type
	)

Initialize a random number generator object

Parameters

rng	rng object
rng_type	type of the rng, possible values: "system": system RNG "user": userspace RNG "user-threadsafe": userspace RNG, with internal locking "rdrand": directly read RDRAND Set rng_type to null to let the library choose some default.

Definition at line 25 of file ffi_rng.cpp.

   {
   return ffi_guard_thunk(__func__, [=]() -> int {
   if(rng_out == nullptr)
      return BOTAN_FFI_ERROR_NULL_POINTER;
 
   const std::string rng_type_s(rng_type ? rng_type : "system");
 
   std::unique_ptr<Botan::RandomNumberGenerator> rng;
 
   if(rng_type_s == "system")
      {
      rng = std::make_unique<Botan::System_RNG>();
      }
   else if(rng_type_s == "user" || rng_type_s == "user-threadsafe")
      {
      rng = std::make_unique<Botan::AutoSeeded_RNG>();
      }
   else if(rng_type_s == "null")
      {
      rng = std::make_unique<Botan::Null_RNG>();
      }
#if defined(BOTAN_HAS_PROCESSOR_RNG)
   else if((rng_type_s == "rdrand" || rng_type_s == "hwrng") && Botan::Processor_RNG::available())
      {
      rng = std::make_unique<Botan::Processor_RNG>();
      }
#endif
 
   if(!rng)
      {
      return BOTAN_FFI_ERROR_NOT_IMPLEMENTED;
      }
 
   *rng_out = new botan_rng_struct(std::move(rng));
   return BOTAN_FFI_SUCCESS;
   });
   }

References Botan::Processor_RNG::available(), BOTAN_FFI_ERROR_NOT_IMPLEMENTED, BOTAN_FFI_ERROR_NULL_POINTER, BOTAN_FFI_SUCCESS, and Botan_FFI::ffi_guard_thunk().

botan_rng_init_custom()

int botan_rng_init_custom	(	botan_rng_t *	rng_out,
		const char *	rng_name,
		void *	context,
		int(*)(void *context, uint8_t *out, size_t out_len)	get_cb,
		int(*)(void *context, const uint8_t input[], size_t length)	add_entropy_cb,
		void(*)(void *context)	destroy_cb
	)

Initialize a custom random number generator from a set of callback functions

Parameters

rng_out	rng object to create
rng_name	name of the rng
context	An application-specific context passed to the callback functions
get_cb	Callback for getting random bytes from the rng, return 0 for success
add_entropy_cb	Callback for adding entropy to the rng, return 0 for success, may be NULL
destroy_cb	Callback called when rng is destroyed, may be NULL

Definition at line 64 of file ffi_rng.cpp.

   {
   return ffi_guard_thunk(__func__,[=]() -> int {
   if(rng_out == nullptr)
      return BOTAN_FFI_ERROR_NULL_POINTER;
 
   if(rng_name == nullptr)
      return BOTAN_FFI_ERROR_NULL_POINTER;
 
   if(get_cb == nullptr)
      return BOTAN_FFI_ERROR_NULL_POINTER;
 
   class Custom_RNG : public Botan::RandomNumberGenerator
      {
      public:
         Custom_RNG(std::string_view name, void* context,
                    int(* get_cb)(void* context, uint8_t* out, size_t out_len),
                    int(* add_entropy_cb)(void* context, const uint8_t input[], size_t length),
                    void(* destroy_cb)(void* context)) :
            m_name(name)
            {
            m_context = context;
            m_get_cb = get_cb;
            m_add_entropy_cb = add_entropy_cb;
            m_destroy_cb = destroy_cb;
            }
 
         ~Custom_RNG() override
            {
            if(m_destroy_cb)
               {
               m_destroy_cb(m_context);
               }
            }
 
         Custom_RNG(const Custom_RNG& other) = delete;
         Custom_RNG(Custom_RNG&& other) = delete;
         Custom_RNG& operator=(const Custom_RNG& other) = delete;
         Custom_RNG& operator=(Custom_RNG&& other) = delete;
 
      protected:
         void fill_bytes_with_input(std::span<uint8_t> output, std::span<const uint8_t> input) override
            {
            if(accepts_input() && !input.empty())
               {
               int rc = m_add_entropy_cb(m_context, input.data(), input.size());
               if(rc)
                  {
                  throw Botan::Invalid_State("Failed to add entropy via C callback, rc=" + std::to_string(rc));
                  }
               }
 
            if(!output.empty())
               {
               int rc = m_get_cb(m_context, output.data(), output.size());
               if(rc)
                  {
                  throw Botan::Invalid_State("Failed to get random from C callback, rc=" + std::to_string(rc));
                  }
               }
            }
 
      public:
         bool accepts_input() const override
            {
            return m_add_entropy_cb != nullptr;
            }
 
         std::string name() const override
            {
            return m_name;
            }
 
         void clear() override
            {
            }
 
         bool is_seeded() const override
            {
            return true;
            }
 
      private:
         std::string m_name;
         void* m_context;
         std::function<int(void* context, uint8_t* out, size_t out_len)> m_get_cb;
         std::function<int(void* context, const uint8_t input[], size_t length)> m_add_entropy_cb;
         std::function<void(void* context)> m_destroy_cb;
      };
 
   auto rng = std::make_unique<Custom_RNG>(rng_name, context, get_cb, add_entropy_cb, destroy_cb);
 
   *rng_out = new botan_rng_struct(std::move(rng));
   return BOTAN_FFI_SUCCESS;
   });
   }

References BOTAN_FFI_ERROR_NULL_POINTER, BOTAN_FFI_SUCCESS, Botan_FFI::ffi_guard_thunk(), and name.

botan_rng_reseed()

int botan_rng_reseed	(	botan_rng_t	rng,
		size_t	bits
	)

Reseed a random number generator Uses the System_RNG as a seed generator.

Parameters

rng	rng object
bits	number of bits to reseed with

Returns

0 on success, a negative value on failure

Definition at line 183 of file ffi_rng.cpp.

   {
   return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.reseed_from_rng(Botan::system_rng(), bits); });
   }

References BOTAN_FFI_VISIT, and Botan::system_rng().

botan_rng_reseed_from_rng()

int botan_rng_reseed_from_rng	(	botan_rng_t	rng,
		botan_rng_t	source_rng,
		size_t	bits
	)

Reseed a random number generator

Parameters

rng	rng object
source_rng	the rng that will be read from
bits	number of bits to reseed with

Returns

0 on success, a negative value on failure

Definition at line 193 of file ffi_rng.cpp.

   {
   return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.reseed_from_rng(safe_get(source_rng), bits); });
   }

References BOTAN_FFI_VISIT, and Botan_FFI::safe_get().

botan_system_rng_get()

int botan_system_rng_get	(	uint8_t *	out,
		size_t	out_len
	)

Get random bytes from system random number generator

Parameters

out	output buffer of size out_len
out_len	number of requested bytes

Returns

0 on success, negative on failure

Definition at line 174 of file ffi_rng.cpp.

   {
   return ffi_guard_thunk(__func__, [=]() -> int
      {
      Botan::system_rng().randomize(out, out_len);
      return BOTAN_FFI_SUCCESS;
      });
   }

References BOTAN_FFI_SUCCESS, Botan_FFI::ffi_guard_thunk(), Botan::RandomNumberGenerator::randomize(), and Botan::system_rng().