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/*
* BigInt Random Generation
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/bigint.h>
#include <botan/parsing.h>
namespace Botan {
/*
* Construct a BigInt of a specific form
*/
BigInt::BigInt(NumberType type, u32bit bits)
{
set_sign(Positive);
if(type == Power2)
set_bit(bits);
else
throw Invalid_Argument("BigInt(NumberType): Unknown type");
}
/*
* Randomize this number
*/
void BigInt::randomize(RandomNumberGenerator& rng,
u32bit bitsize)
{
set_sign(Positive);
if(bitsize == 0)
clear();
else
{
SecureVector<byte> array = rng.random_vec((bitsize + 7) / 8);
if(bitsize % 8)
array[0] &= 0xFF >> (8 - (bitsize % 8));
array[0] |= 0x80 >> ((bitsize % 8) ? (8 - bitsize % 8) : 0);
binary_decode(&array[0], array.size());
}
}
/*
* Generate a random integer within given range
*/
BigInt BigInt::random_integer(RandomNumberGenerator& rng,
const BigInt& min, const BigInt& max)
{
BigInt range = max - min;
if(range <= 0)
throw Invalid_Argument("random_integer: invalid min/max values");
return (min + (BigInt(rng, range.bits() + 2) % range));
}
}
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