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LibCrypto: Add a simple SignedBigInteger

This patchset adds a simple SignedBigInteger that is entirely defined in
terms of UnsignedBigInteger.

It also adds a NumberTheory::Power function, which is terribly
inefficient, but since the use of exponentiation is very much
discouraged for large inputs, no particular attempts were made
to make it more performant.
This commit is contained in:
AnotherTest 2020-06-04 22:46:18 +04:30 committed by Andreas Kling
parent b4591f0037
commit d8208fd37c
5 changed files with 661 additions and 0 deletions

View file

@ -0,0 +1,159 @@
/*
* Copyright (c) 2020, the SerenityOS developers.
* 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 <LibCrypto/BigInt/UnsignedBigInteger.h>
namespace Crypto {
struct SignedDivisionResult;
class SignedBigInteger {
public:
SignedBigInteger(i32 x)
: m_sign(x < 0)
, m_unsigned_data(abs(x))
{
}
SignedBigInteger(UnsignedBigInteger&& unsigned_data, bool sign)
: m_sign(sign)
, m_unsigned_data(move(unsigned_data))
{
}
explicit SignedBigInteger(UnsignedBigInteger unsigned_data)
: m_sign(false)
, m_unsigned_data(move(unsigned_data))
{
}
SignedBigInteger()
: m_sign(false)
, m_unsigned_data()
{
}
static SignedBigInteger create_invalid()
{
return { UnsignedBigInteger::create_invalid(), false };
}
static SignedBigInteger import_data(const AK::StringView& data) { return import_data((const u8*)data.characters_without_null_termination(), data.length()); }
static SignedBigInteger import_data(const u8* ptr, size_t length);
size_t export_data(AK::ByteBuffer& data) const;
size_t export_data(const u8* ptr, size_t length) const
{
auto buffer = ByteBuffer::wrap(ptr, length);
return export_data(buffer);
}
static SignedBigInteger from_base10(StringView str);
String to_base10() const;
const UnsignedBigInteger& unsigned_value() const { return m_unsigned_data; }
const Vector<u32, STARTING_WORD_SIZE> words() const { return m_unsigned_data.words(); }
bool is_negative() const { return m_sign; }
void negate() { m_sign = !m_sign; }
void set_to_0() { m_unsigned_data.set_to_0(); }
void set_to(i32 other)
{
m_unsigned_data.set_to((u32)other);
m_sign = other < 0;
}
void set_to(const SignedBigInteger& other)
{
m_unsigned_data.set_to(other.m_unsigned_data);
m_sign = other.m_sign;
}
void invalidate()
{
m_unsigned_data.invalidate();
}
bool is_invalid() const { return m_unsigned_data.is_invalid(); }
// These get + 1 byte for the sign.
size_t length() const { return m_unsigned_data.length() + 1; }
size_t trimmed_length() const { return m_unsigned_data.trimmed_length() + 1; };
SignedBigInteger plus(const SignedBigInteger& other) const;
SignedBigInteger minus(const SignedBigInteger& other) const;
SignedBigInteger shift_left(size_t num_bits) const;
SignedBigInteger multiplied_by(const SignedBigInteger& other) const;
SignedDivisionResult divided_by(const SignedBigInteger& divisor) const;
SignedBigInteger plus(const UnsignedBigInteger& other) const;
SignedBigInteger minus(const UnsignedBigInteger& other) const;
SignedBigInteger multiplied_by(const UnsignedBigInteger& other) const;
SignedDivisionResult divided_by(const UnsignedBigInteger& divisor) const;
void set_bit_inplace(size_t bit_index);
bool operator==(const SignedBigInteger& other) const;
bool operator!=(const SignedBigInteger& other) const;
bool operator<(const SignedBigInteger& other) const;
bool operator==(const UnsignedBigInteger& other) const;
bool operator!=(const UnsignedBigInteger& other) const;
bool operator<(const UnsignedBigInteger& other) const;
private:
bool m_sign { false };
UnsignedBigInteger m_unsigned_data;
};
struct SignedDivisionResult {
Crypto::SignedBigInteger quotient;
Crypto::SignedBigInteger remainder;
};
}
inline const LogStream&
operator<<(const LogStream& stream, const Crypto::SignedBigInteger value)
{
if (value.is_invalid()) {
stream << "Invalid BigInt";
return stream;
}
if (value.is_negative())
stream << "-";
stream << value.unsigned_value();
return stream;
}
inline Crypto::SignedBigInteger
operator""_sbigint(const char* string, size_t length)
{
return Crypto::SignedBigInteger::from_base10({ string, length });
}