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/*
* RandomNumberGenerator
* (C) 1999-2009 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_RANDOM_NUMBER_GENERATOR_H__
#define BOTAN_RANDOM_NUMBER_GENERATOR_H__
#include <botan/entropy_src.h>
#include <botan/exceptn.h>
#include <string>
namespace Botan {
/**
* This class represents a random number (RNG) generator object.
*/
class BOTAN_DLL RandomNumberGenerator
{
public:
/**
* Create a seeded and active RNG object for general application use
*/
static RandomNumberGenerator* make_rng();
/**
* Randomize a byte array.
* @param output the byte array to hold the random output.
* @param length the length of the byte array output.
*/
virtual void randomize(byte output[], u32bit length) = 0;
/**
* Return a random byte
* @return random byte
*/
byte next_byte();
/**
* Check whether this RNG is seeded.
* @return true if this RNG was already seeded, false otherwise.
*/
virtual bool is_seeded() const { return true; }
/**
* Clear all internally held values of this RNG.
*/
virtual void clear() = 0;
/**
* Return the name of this object
*/
virtual std::string name() const = 0;
/**
* Seed this RNG using the entropy sources it contains.
* @param bits_to_collect is the number of bits of entropy to
attempt to gather from the entropy sources
*/
virtual void reseed(u32bit bits_to_collect) = 0;
/**
* Add this entropy source to the RNG object
* @param source the entropy source which will be retained and used by RNG
*/
virtual void add_entropy_source(EntropySource* source) = 0;
/**
* Add entropy to this RNG.
* @param in a byte array containg the entropy to be added
* @param length the length of the byte array in
*/
virtual void add_entropy(const byte in[], u32bit length) = 0;
RandomNumberGenerator() {}
virtual ~RandomNumberGenerator() {}
private:
RandomNumberGenerator(const RandomNumberGenerator&) {}
RandomNumberGenerator& operator=(const RandomNumberGenerator&)
{ return (*this); }
};
/**
* Null/stub RNG - fails if you try to use it for anything
*/
class BOTAN_DLL Null_RNG : public RandomNumberGenerator
{
public:
void randomize(byte[], u32bit) { throw PRNG_Unseeded("Null_RNG"); }
void clear() {}
std::string name() const { return "Null_RNG"; }
void reseed(u32bit) {}
bool is_seeded() const { return false; }
void add_entropy(const byte[], u32bit) {}
void add_entropy_source(EntropySource* es) { delete es; }
};
}
#endif
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