ladybird/Libraries/LibCrypto/Cipher/Mode/Mode.h

/*
 * Copyright (c) 2020, Ali Mohammad Pur <ali.mpfard@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 <LibCrypto/Cipher/Cipher.h>

namespace Crypto {
namespace Cipher {

    template <typename T>
    class Mode {
    public:
        // FIXME: Somehow communicate that encrypt returns the last initialization vector (if the mode supports it)
        virtual Optional<ByteBuffer> encrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) = 0;
        virtual void decrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) = 0;

        const T& cipher() const { return m_cipher; }

        ByteBuffer create_aligned_buffer(size_t input_size) const
        {
            size_t remainder = (input_size + T::block_size()) % T::block_size();
            if (remainder == 0)
                return ByteBuffer::create_uninitialized(input_size);
            else
                return ByteBuffer::create_uninitialized(input_size + T::block_size() - remainder);
        }

    protected:
        T& cipher() { return m_cipher; }

        virtual void prune_padding(ByteBuffer& data)
        {
            auto size = data.size();
            switch (m_cipher.padding_mode()) {
            case PaddingMode::CMS: {
                auto maybe_padding_length = data[size - 1];
                if (maybe_padding_length >= T::block_size()) {
                    // cannot be padding (the entire block cannot be padding)
                    return;
                }
                for (auto i = maybe_padding_length; i > 0; --i) {
                    if (data[size - i] != maybe_padding_length) {
                        // not padding, part of data
                        return;
                    }
                }
                data.trim(size - maybe_padding_length);
                break;
            }
            case PaddingMode::Null: {
                while (data[size - 1] == 0)
                    --size;
                data.trim(size);
                break;
            }
            default:
                // FIXME: support other padding modes
                ASSERT_NOT_REACHED();
                break;
            }
        }

        // FIXME: Somehow add a reference version of this
        template <typename... Args>
        Mode(Args... args)
            : m_cipher(args...)
        {
        }

    private:
        T m_cipher;
    };
}

}