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/*
* Copyright (c) 2020, Ali Mohammad Pur <mpfard@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Random.h>
#include <LibCrypto/BigInt/UnsignedBigInteger.h>
namespace Crypto {
namespace NumberTheory {
UnsignedBigInteger ModularInverse(UnsignedBigInteger const& a_, UnsignedBigInteger const& b);
UnsignedBigInteger ModularPower(UnsignedBigInteger const& b, UnsignedBigInteger const& e, UnsignedBigInteger const& m);
// Note: This function _will_ generate extremely huge numbers, and in doing so,
// it will allocate and free a lot of memory!
// Please use |ModularPower| if your use-case is modexp.
template<typename IntegerType>
static IntegerType Power(IntegerType const& b, IntegerType const& e)
{
IntegerType ep { e };
IntegerType base { b };
IntegerType exp { 1 };
while (!(ep < IntegerType { 1 })) {
if (ep.words()[0] % 2 == 1)
exp.set_to(exp.multiplied_by(base));
// ep = ep / 2;
ep.set_to(ep.divided_by(IntegerType { 2 }).quotient);
// base = base * base
base.set_to(base.multiplied_by(base));
}
return exp;
}
UnsignedBigInteger GCD(UnsignedBigInteger const& a, UnsignedBigInteger const& b);
UnsignedBigInteger LCM(UnsignedBigInteger const& a, UnsignedBigInteger const& b);
UnsignedBigInteger random_number(UnsignedBigInteger const& min, UnsignedBigInteger const& max_excluded);
bool is_probably_prime(UnsignedBigInteger const& p);
UnsignedBigInteger random_big_prime(size_t bits);
}
}
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