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/*
* 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/String.h>
#include <AK/StringBuilder.h>
#include <LibCrypto/Cipher/Mode/Mode.h>
namespace Crypto {
namespace Cipher {
template <typename T>
class CBC : public Mode<T> {
public:
virtual ~CBC() {}
template <typename... Args>
explicit constexpr CBC<T>(Args... args)
: Mode<T>(args...)
{
}
virtual String class_name() const override
{
StringBuilder builder;
builder.append(this->cipher().class_name());
builder.append("_CBC");
return builder.build();
}
virtual Optional<ByteBuffer> encrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
{
auto length = in.size();
if (length == 0)
return {};
auto& cipher = this->cipher();
// FIXME: We should have two of these encrypt/decrypt functions that
// we SFINAE out based on whether the Cipher mode needs an ivec
ASSERT(ivec.has_value());
const auto* iv = ivec.value().data();
typename T::BlockType block { cipher.padding_mode() };
size_t offset { 0 };
auto block_size = cipher.block_size();
while (length >= block_size) {
block.overwrite(in.slice_view(offset, block_size));
block.apply_initialization_vector(iv);
cipher.encrypt_block(block, block);
out.overwrite(offset, block.get().data(), block_size);
iv = out.offset_pointer(offset);
length -= block_size;
offset += block_size;
}
if (length > 0) {
block.overwrite(in.slice_view(offset, length));
block.apply_initialization_vector(iv);
cipher.encrypt_block(block, block);
out.overwrite(offset, block.get().data(), block_size);
iv = out.offset_pointer(offset);
}
return ByteBuffer::copy(iv, block_size);
}
virtual void decrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
{
auto length = in.size();
if (length == 0)
return;
auto& cipher = this->cipher();
ASSERT(ivec.has_value());
const auto* iv = ivec.value().data();
auto block_size = cipher.block_size();
// if the data is not aligned, it's not correct encrypted data
// FIXME (ponder): Should we simply decrypt as much as we can?
ASSERT(length % block_size == 0);
typename T::BlockType block { cipher.padding_mode() };
size_t offset { 0 };
while (length > 0) {
auto* slice = in.offset_pointer(offset);
block.overwrite(slice, block_size);
cipher.decrypt_block(block, block);
block.apply_initialization_vector(iv);
auto decrypted = block.get();
out.overwrite(offset, decrypted.data(), decrypted.size());
iv = slice;
length -= block_size;
offset += block_size;
}
out.trim(offset);
this->prune_padding(out);
}
};
}
}
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