55 lines
2.1 KiB
C++
55 lines
2.1 KiB
C++
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// Copyright 2018 yuzu emulator team
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <cstring>
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#include "common/assert.h"
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#include "core/crypto/xts_encryption_layer.h"
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namespace Core::Crypto {
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XTSEncryptionLayer::XTSEncryptionLayer(FileSys::VirtualFile base_, Key256 key_)
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: EncryptionLayer(std::move(base_)), cipher(key_, Mode::XTS) {}
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size_t XTSEncryptionLayer::Read(u8* data, size_t length, size_t offset) const {
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if (length == 0)
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return 0;
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const auto sector_offset = offset & 0x3FFF;
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if (sector_offset == 0) {
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if (length % 0x4000 == 0) {
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std::vector<u8> raw = base->ReadBytes(length, offset);
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cipher.XTSTranscode(raw.data(), raw.size(), data, offset / 0x4000, 0x4000, Op::Decrypt);
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return raw.size();
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}
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if (length > 0x4000) {
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const auto rem = length % 0x4000;
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const auto read = length - rem;
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return Read(data, read, offset) + Read(data + read, rem, offset + read);
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}
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std::vector<u8> buffer = base->ReadBytes(0x4000, offset);
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if (buffer.size() < 0x4000)
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buffer.resize(0x4000);
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cipher.XTSTranscode(buffer.data(), buffer.size(), buffer.data(), offset / 0x4000, 0x4000,
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Op::Decrypt);
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std::memcpy(data, buffer.data(), std::min(buffer.size(), length));
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return std::min(buffer.size(), length);
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}
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// offset does not fall on block boundary (0x4000)
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std::vector<u8> block = base->ReadBytes(0x4000, offset - sector_offset);
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if (block.size() < 0x4000)
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block.resize(0x4000);
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cipher.XTSTranscode(block.data(), block.size(), block.data(), (offset - sector_offset) / 0x4000,
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0x4000, Op::Decrypt);
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const size_t read = 0x4000 - sector_offset;
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if (length + sector_offset < 0x4000) {
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std::memcpy(data, block.data() + sector_offset, std::min<u64>(length, read));
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return std::min<u64>(length, read);
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}
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std::memcpy(data, block.data() + sector_offset, read);
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return read + Read(data + read, length - read, offset + read);
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}
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} // namespace Core::Crypto
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