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LibCrypto: Add CTR cipher mode
Kernel: Changed fortuna implementation to use CTR mode instead of manually implementing a counter.
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3 changed files with 153 additions and 26 deletions
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@ -30,6 +30,7 @@
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#include <AK/Vector.h>
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#include <LibCrypto/Cipher/Cipher.h>
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#include <LibCrypto/Cipher/Mode/CBC.h>
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#include <LibCrypto/Cipher/Mode/CTR.h>
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namespace Crypto {
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namespace Cipher {
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@ -110,6 +111,7 @@ private:
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class AESCipher final : public Cipher<AESCipherKey, AESCipherBlock> {
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public:
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using CBCMode = CBC<AESCipher>;
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using CTRMode = CTR<AESCipher>;
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constexpr static size_t BlockSizeInBits = BlockType::BlockSizeInBits;
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138
Libraries/LibCrypto/Cipher/Mode/CTR.h
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138
Libraries/LibCrypto/Cipher/Mode/CTR.h
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@ -0,0 +1,138 @@
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/*
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* Copyright (c) 2020, Peter Elliott <pelliott@ualberta.ca>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/String.h>
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#include <AK/StringBuilder.h>
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#include <AK/StringView.h>
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#include <LibCrypto/Cipher/Mode/Mode.h>
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namespace Crypto {
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namespace Cipher {
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template<typename T>
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class CTR : public Mode<T> {
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public:
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constexpr static size_t IVSizeInBits = 128;
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virtual ~CTR() { }
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template<typename... Args>
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explicit constexpr CTR<T>(Args... args)
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: Mode<T>(args...)
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{
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}
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virtual String class_name() const override
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{
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StringBuilder builder;
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builder.append(this->cipher().class_name());
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builder.append("_CTR");
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return builder.build();
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}
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virtual size_t IV_length() const override { return IVSizeInBits / 8; }
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virtual Optional<ByteBuffer> encrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
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{
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return this->encrypt_or_stream(&in, out, ivec);
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}
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Optional<ByteBuffer> key_stream(ByteBuffer& out, Optional<ByteBuffer> ivec = {})
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{
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return this->encrypt_or_stream(nullptr, out, ivec);
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}
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virtual void decrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
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{
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(void)in;
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(void)out;
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(void)ivec;
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// FIXME: Implement CTR decryption when it is needed.
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}
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private:
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static ByteBuffer increment(const ByteBuffer& in)
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{
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ByteBuffer new_buffer(in);
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size_t* num_view = (size_t*)new_buffer.data();
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for (size_t i = 0; i < in.size() / sizeof(size_t); ++i) {
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if (num_view[i] == (size_t)-1) {
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num_view[i] = 0;
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} else {
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num_view[i]++;
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break;
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}
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}
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return new_buffer;
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}
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Optional<ByteBuffer> encrypt_or_stream(const ByteBuffer* in, ByteBuffer& out, Optional<ByteBuffer> ivec)
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{
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size_t length;
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if (in) {
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ASSERT(in->size() <= out.size());
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length = in->size();
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if (length == 0)
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return {};
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} else {
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length = out.size();
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}
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auto& cipher = this->cipher();
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// FIXME: We should have two of these encrypt/decrypt functions that
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// we SFINAE out based on whether the Cipher mode needs an ivec
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ASSERT(ivec.has_value());
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auto iv = ivec.value();
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typename T::BlockType block { cipher.padding_mode() };
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size_t offset { 0 };
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auto block_size = cipher.block_size();
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while (length > 0) {
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block.overwrite(iv.slice_view(0, block_size));
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cipher.encrypt_block(block, block);
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if (in) {
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block.apply_initialization_vector(in->data() + offset);
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}
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auto write_size = min(block_size, length);
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out.overwrite(offset, block.get().data(), write_size);
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iv = increment(iv);
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length -= write_size;
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offset += write_size;
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}
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return iv;
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}
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};
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}
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}
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