100 lines
2.8 KiB
C++
100 lines
2.8 KiB
C++
/*
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* Copyright (c) 2020, Ali Mohammad Pur <mpfard@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/ByteBuffer.h>
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#include <AK/Span.h>
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#include <LibCrypto/Cipher/Cipher.h>
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namespace Crypto::Cipher {
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template<typename T>
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class Mode {
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public:
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virtual ~Mode() = default;
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virtual void encrypt(ReadonlyBytes in, Bytes& out, ReadonlyBytes ivec = {}, Bytes* ivec_out = nullptr) = 0;
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virtual void decrypt(ReadonlyBytes in, Bytes& out, ReadonlyBytes ivec = {}) = 0;
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virtual size_t IV_length() const = 0;
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T const& cipher() const { return m_cipher; }
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static ErrorOr<ByteBuffer> create_aligned_buffer(size_t input_size)
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{
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size_t remainder = (input_size + T::block_size()) % T::block_size();
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if (remainder == 0)
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return ByteBuffer::create_uninitialized(input_size);
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else
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return ByteBuffer::create_uninitialized(input_size + T::block_size() - remainder);
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}
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#ifndef KERNEL
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virtual DeprecatedString class_name() const = 0;
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#endif
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T& cipher()
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{
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return m_cipher;
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}
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protected:
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virtual void prune_padding(Bytes& data)
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{
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auto size = data.size();
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switch (m_cipher.padding_mode()) {
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case PaddingMode::CMS: {
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auto maybe_padding_length = data[size - 1];
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if (maybe_padding_length >= T::block_size()) {
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// cannot be padding (the entire block cannot be padding)
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return;
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}
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for (auto i = size - maybe_padding_length; i < size; ++i) {
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if (data[i] != maybe_padding_length) {
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// not padding, part of data
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return;
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}
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}
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data = data.slice(0, size - maybe_padding_length);
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break;
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}
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case PaddingMode::RFC5246: {
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auto maybe_padding_length = data[size - 1];
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// FIXME: If we want constant-time operations, this loop should not stop
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for (auto i = size - maybe_padding_length - 1; i < size; ++i) {
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if (data[i] != maybe_padding_length) {
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// note that this is likely invalid padding
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return;
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}
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}
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data = data.slice(0, size - maybe_padding_length - 1);
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break;
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}
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case PaddingMode::Null: {
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while (data[size - 1] == 0)
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--size;
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data = data.slice(0, size);
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break;
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}
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default:
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// FIXME: support other padding modes
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VERIFY_NOT_REACHED();
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break;
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}
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}
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// FIXME: Somehow add a reference version of this
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template<typename... Args>
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Mode(Args... args)
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: m_cipher(args...)
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{
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}
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private:
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T m_cipher;
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};
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}
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