OW_CryptographicRandomNumber.hpp

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#ifndef OW_CRYPTOGRAPHIC_RANDOM_NUMBER_HPP_INCLUDE_GUARD_
#define OW_CRYPTOGRAPHIC_RANDOM_NUMBER_HPP_INCLUDE_GUARD_
#include "OW_config.h"
#include "OW_Exception.hpp"

namespace OW_NAMESPACE
{

OW_DECLARE_APIEXCEPTION(CryptographicRandomNumber, OW_COMMON_API);

} // end namespace OW_NAMESPACE

#if defined(OW_HAVE_OPENSSL)
#include "OW_Types.hpp"

#include <stdlib.h> // for RAND_MAX

namespace OW_NAMESPACE
{

class OW_COMMON_API CryptographicRandomNumber
{
public:
   // Precondition: lowVal < highVal
   CryptographicRandomNumber(Int32 lowVal = 0, Int32 highVal = RAND_MAX);
   Int32 getNextNumber();
   
public:
   // This function can be called to control when the openssl cryptographic prng will be initialized.
   // It may be a lengthy process on some OSs which don't have /dev/urandom. If it hasn't been previously
   // called, it will be called the first time a CryptographicRandomNumber instance is instantiated.
   // It's okay to call this function multiple times from multiple threads.
   static void initRandomness();
   static void saveRandomState();

private:
   Int32 m_lowVal;
   Int32 m_highVal;
   Int32 m_range;
   int m_numBits;
};

} // end namespace OW_NAMESPACE

#else

// no openssl, so just typedef the class to RandomNumber
#include "OW_RandomNumber.hpp"

namespace OW_NAMESPACE
{

typedef RandomNumber CryptographicRandomNumber;

} // end namespace OW_NAMESPACE

#endif // #if defined(OW_HAVE_OPENSSL)

#endif

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