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// --------------------------------------------------------------------------
//
// File
// Name: Random.cpp
// Purpose: Random numbers
// Created: 31/12/03
//
// --------------------------------------------------------------------------
#include "Box.h"
#include <openssl/rand.h>
#include <stdio.h>
#include "Random.h"
#include "CipherException.h"
#include "MemLeakFindOn.h"
// --------------------------------------------------------------------------
//
// Function
// Name: Random::Initialise()
// Purpose: Add additional randomness to the standard library initialisation
// Created: 18/6/04
//
// --------------------------------------------------------------------------
void Random::Initialise()
{
#ifdef HAVE_RANDOM_DEVICE
if(::RAND_load_file(RANDOM_DEVICE, 1024) != 1024)
{
THROW_EXCEPTION(CipherException, RandomInitFailed)
}
#else
BOX_ERROR("No random device -- additional seeding of random number "
"generator not performed.");
#endif
}
// --------------------------------------------------------------------------
//
// Function
// Name: Random::Generate(void *, int)
// Purpose: Generate Length bytes of random data
// Created: 31/12/03
//
// --------------------------------------------------------------------------
void Random::Generate(void *pOutput, int Length)
{
if(RAND_bytes((uint8_t*)pOutput, Length) == -1)
{
THROW_EXCEPTION(CipherException, PseudoRandNotAvailable)
}
}
// --------------------------------------------------------------------------
//
// Function
// Name: Random::GenerateHex(int)
// Purpose: Generate Length bytes of hex encoded data. Note that the
// maximum length requested is limited. (Returns a string
// 2 x Length characters long.)
// Created: 1/11/04
//
// --------------------------------------------------------------------------
std::string Random::GenerateHex(int Length)
{
uint8_t r[256];
if(Length > (int)sizeof(r))
{
THROW_EXCEPTION(CipherException, LengthRequestedTooLongForRandomHex)
}
Random::Generate(r, Length);
std::string o;
static const char *h = "0123456789abcdef";
for(int l = 0; l < Length; ++l)
{
o += h[r[l] >> 4];
o += h[r[l] & 0xf];
}
return o;
}
// --------------------------------------------------------------------------
//
// Function
// Name: Random::RandomInt(int)
// Purpose: Return a random integer between 0 and MaxValue inclusive.
// Created: 21/1/04
//
// --------------------------------------------------------------------------
uint32_t Random::RandomInt(uint32_t MaxValue)
{
uint32_t v = 0;
// Generate a mask
uint32_t mask = 0;
while(mask < MaxValue)
{
mask = (mask << 1) | 1;
}
do
{
// Generate a random number
uint32_t r = 0;
Random::Generate(&r, sizeof(r));
// Mask off relevant bits
v = r & mask;
// Check that it's in the right range.
} while(v > MaxValue);
// NOTE: don't do a mod, because this doesn't give a correct random distribution
return v;
}
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