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serenity/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
AnotherTest 2601441486 LibCrypto: Avoid overly big allocs in intermediate ModularPower results
If we don't limit the sizes of the intermediate results, they will grow
indefinitely, causing each iteration to take longer and longer (in both
memcpy time, and algorithm runtime).
While calculating the trimmed length is fairly expensive, it's a small
cost to pay for uniform iteration times.
2021-04-03 11:22:01 +02:00

144 lines
6.5 KiB
C++

/*
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/ByteBuffer.h>
#include <AK/Span.h>
#include <AK/String.h>
#include <AK/Types.h>
#include <AK/Vector.h>
namespace Crypto {
struct UnsignedDivisionResult;
constexpr size_t STARTING_WORD_SIZE = 512;
class UnsignedBigInteger {
public:
UnsignedBigInteger(u32 x) { m_words.append(x); }
explicit UnsignedBigInteger(Vector<u32, STARTING_WORD_SIZE>&& words)
: m_words(move(words))
{
}
explicit UnsignedBigInteger(const u8* ptr, size_t length);
UnsignedBigInteger() { }
static UnsignedBigInteger create_invalid();
static UnsignedBigInteger import_data(const StringView& data) { return import_data((const u8*)data.characters_without_null_termination(), data.length()); }
static UnsignedBigInteger import_data(const u8* ptr, size_t length)
{
return UnsignedBigInteger(ptr, length);
}
size_t export_data(Bytes, bool remove_leading_zeros = false) const;
static UnsignedBigInteger from_base10(const String& str);
String to_base10() const;
const Vector<u32, STARTING_WORD_SIZE>& words() const { return m_words; }
void set_to_0();
void set_to(u32 other);
void set_to(const UnsignedBigInteger& other);
void invalidate()
{
m_is_invalid = true;
m_cached_trimmed_length = {};
}
bool is_invalid() const { return m_is_invalid; }
size_t length() const { return m_words.size(); }
// The "trimmed length" is the number of words after trimming leading zeroed words
size_t trimmed_length() const;
void clamp_to_trimmed_length();
UnsignedBigInteger plus(const UnsignedBigInteger& other) const;
UnsignedBigInteger minus(const UnsignedBigInteger& other) const;
UnsignedBigInteger bitwise_or(const UnsignedBigInteger& other) const;
UnsignedBigInteger bitwise_and(const UnsignedBigInteger& other) const;
UnsignedBigInteger bitwise_xor(const UnsignedBigInteger& other) const;
UnsignedBigInteger bitwise_not() const;
UnsignedBigInteger shift_left(size_t num_bits) const;
UnsignedBigInteger multiplied_by(const UnsignedBigInteger& other) const;
UnsignedDivisionResult divided_by(const UnsignedBigInteger& divisor) const;
void set_bit_inplace(size_t bit_index);
static void add_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& output);
static void subtract_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& output);
static void bitwise_or_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& output);
static void bitwise_and_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& output);
static void bitwise_xor_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& output);
static void bitwise_not_without_allocation(const UnsignedBigInteger& left, UnsignedBigInteger& output);
static void shift_left_without_allocation(const UnsignedBigInteger& number, size_t bits_to_shift_by, UnsignedBigInteger& temp_result, UnsignedBigInteger& temp_plus, UnsignedBigInteger& output);
static void multiply_without_allocation(const UnsignedBigInteger& left, const UnsignedBigInteger& right, UnsignedBigInteger& temp_shift_result, UnsignedBigInteger& temp_shift_plus, UnsignedBigInteger& temp_shift, UnsignedBigInteger& temp_plus, UnsignedBigInteger& output);
static void divide_without_allocation(const UnsignedBigInteger& numerator, const UnsignedBigInteger& denominator, UnsignedBigInteger& temp_shift_result, UnsignedBigInteger& temp_shift_plus, UnsignedBigInteger& temp_shift, UnsignedBigInteger& temp_minus, UnsignedBigInteger& quotient, UnsignedBigInteger& remainder);
static void divide_u16_without_allocation(const UnsignedBigInteger& numerator, u32 denominator, UnsignedBigInteger& quotient, UnsignedBigInteger& remainder);
bool operator==(const UnsignedBigInteger& other) const;
bool operator!=(const UnsignedBigInteger& other) const;
bool operator<(const UnsignedBigInteger& other) const;
private:
ALWAYS_INLINE static void shift_left_by_n_words(const UnsignedBigInteger& number, size_t number_of_words, UnsignedBigInteger& output);
ALWAYS_INLINE static u32 shift_left_get_one_word(const UnsignedBigInteger& number, size_t num_bits, size_t result_word_index);
static constexpr size_t BITS_IN_WORD = 32;
// Little endian
// m_word[0] + m_word[1] * 256 + m_word[2] * 65536 + ...
Vector<u32, STARTING_WORD_SIZE> m_words;
// Used to indicate a negative result, or a result of an invalid operation
bool m_is_invalid { false };
mutable Optional<size_t> m_cached_trimmed_length;
};
struct UnsignedDivisionResult {
Crypto::UnsignedBigInteger quotient;
Crypto::UnsignedBigInteger remainder;
};
}
template<>
struct AK::Formatter<Crypto::UnsignedBigInteger> : Formatter<StringView> {
void format(FormatBuilder&, const Crypto::UnsignedBigInteger&);
};
inline Crypto::UnsignedBigInteger
operator""_bigint(const char* string, size_t length)
{
return Crypto::UnsignedBigInteger::from_base10({ string, length });
}