diff options
Diffstat (limited to 'src/core/crypto/xts_encryption_layer.cpp')
-rw-r--r-- | src/core/crypto/xts_encryption_layer.cpp | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/src/core/crypto/xts_encryption_layer.cpp b/src/core/crypto/xts_encryption_layer.cpp new file mode 100644 index 000000000..c10832cfe --- /dev/null +++ b/src/core/crypto/xts_encryption_layer.cpp @@ -0,0 +1,58 @@ +// Copyright 2018 yuzu emulator team +// Licensed under GPLv2 or any later version +// Refer to the license.txt file included. + +#include <algorithm> +#include <cstring> +#include "common/assert.h" +#include "core/crypto/xts_encryption_layer.h" + +namespace Core::Crypto { + +constexpr u64 XTS_SECTOR_SIZE = 0x4000; + +XTSEncryptionLayer::XTSEncryptionLayer(FileSys::VirtualFile base_, Key256 key_) + : EncryptionLayer(std::move(base_)), cipher(key_, Mode::XTS) {} + +size_t XTSEncryptionLayer::Read(u8* data, size_t length, size_t offset) const { + if (length == 0) + return 0; + + const auto sector_offset = offset & 0x3FFF; + if (sector_offset == 0) { + if (length % XTS_SECTOR_SIZE == 0) { + std::vector<u8> raw = base->ReadBytes(length, offset); + cipher.XTSTranscode(raw.data(), raw.size(), data, offset / XTS_SECTOR_SIZE, + XTS_SECTOR_SIZE, Op::Decrypt); + return raw.size(); + } + if (length > XTS_SECTOR_SIZE) { + const auto rem = length % XTS_SECTOR_SIZE; + const auto read = length - rem; + return Read(data, read, offset) + Read(data + read, rem, offset + read); + } + std::vector<u8> buffer = base->ReadBytes(XTS_SECTOR_SIZE, offset); + if (buffer.size() < XTS_SECTOR_SIZE) + buffer.resize(XTS_SECTOR_SIZE); + cipher.XTSTranscode(buffer.data(), buffer.size(), buffer.data(), offset / XTS_SECTOR_SIZE, + XTS_SECTOR_SIZE, Op::Decrypt); + std::memcpy(data, buffer.data(), std::min(buffer.size(), length)); + return std::min(buffer.size(), length); + } + + // offset does not fall on block boundary (0x4000) + std::vector<u8> block = base->ReadBytes(0x4000, offset - sector_offset); + if (block.size() < XTS_SECTOR_SIZE) + block.resize(XTS_SECTOR_SIZE); + cipher.XTSTranscode(block.data(), block.size(), block.data(), + (offset - sector_offset) / XTS_SECTOR_SIZE, XTS_SECTOR_SIZE, Op::Decrypt); + const size_t read = XTS_SECTOR_SIZE - sector_offset; + + if (length + sector_offset < XTS_SECTOR_SIZE) { + std::memcpy(data, block.data() + sector_offset, std::min<u64>(length, read)); + return std::min<u64>(length, read); + } + std::memcpy(data, block.data() + sector_offset, read); + return read + Read(data + read, length - read, offset + read); +} +} // namespace Core::Crypto |