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crypto: Eliminate magic constants

pull/15/merge
Zach Hilman 7 years ago
parent
61a5b56abd
commit
42dc856ce1
4 changed files with 38 additions and 32 deletions
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  1. 2
      src/core/crypto/key_manager.cpp
  2. 33
      src/core/crypto/xts_encryption_layer.cpp
  3. 25
      src/core/file_sys/xts_archive.cpp
  4. 10
      src/core/file_sys/xts_archive.h

2
src/core/crypto/key_manager.cpp
View File

@ -102,7 +102,7 @@ Loader::ResultStatus DeriveSDKeys(std::array<Key256, 2>& sd_keys, const KeyManag
AESCipher<Key128> cipher(sd_kek, Mode::ECB);
for (size_t i = 0; i < 2; ++i) {
for (size_t j = 0; j < 0x20; ++j)
for (size_t j = 0; j < sd_key_sources[i].size(); ++j)
sd_key_sources[i][j] ^= sd_seed[j & 0xF];
cipher.Transcode(sd_key_sources[i].data(), sd_key_sources[i].size(), sd_keys[i].data(),
Op::Decrypt);

33
src/core/crypto/xts_encryption_layer.cpp
View File

@ -8,6 +8,8 @@
namespace Core::Crypto {
constexpr u64 XTS_SECTOR_SIZE = 0x4000;
XTSEncryptionLayer::XTSEncryptionLayer(FileSys::VirtualFile base_, Key256 key_)
: EncryptionLayer(std::move(base_)), cipher(key_, Mode::XTS) {}
@ -17,34 +19,35 @@ size_t XTSEncryptionLayer::Read(u8* data, size_t length, size_t offset) const {
const auto sector_offset = offset & 0x3FFF;
if (sector_offset == 0) {
if (length % 0x4000 == 0) {
if (length % XTS_SECTOR_SIZE == 0) {
std::vector<u8> raw = base->ReadBytes(length, offset);
cipher.XTSTranscode(raw.data(), raw.size(), data, offset / 0x4000, 0x4000, Op::Decrypt);
cipher.XTSTranscode(raw.data(), raw.size(), data, offset / XTS_SECTOR_SIZE,
XTS_SECTOR_SIZE, Op::Decrypt);
return raw.size();
}
if (length > 0x4000) {
const auto rem = length % 0x4000;
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(0x4000, offset);
if (buffer.size() < 0x4000)
buffer.resize(0x4000);
cipher.XTSTranscode(buffer.data(), buffer.size(), buffer.data(), offset / 0x4000, 0x4000,
Op::Decrypt);
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() < 0x4000)
block.resize(0x4000);
cipher.XTSTranscode(block.data(), block.size(), block.data(), (offset - sector_offset) / 0x4000,
0x4000, Op::Decrypt);
const size_t read = 0x4000 - 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 < 0x4000) {
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);
}

25
src/core/file_sys/xts_archive.cpp
View File

@ -19,6 +19,8 @@
namespace FileSys {
constexpr u64 NAX_HEADER_PADDING_SIZE = 0x4000;
template <typename SourceData, typename SourceKey, typename Destination>
static bool CalculateHMAC256(Destination* out, const SourceKey* key, size_t key_length,
const SourceData* data, size_t data_length) {
@ -67,14 +69,14 @@ NAX::NAX(VirtualFile file_, std::array<u8, 0x10> nca_id)
Common::HexArrayToString(nca_id, false)));
}
Loader::ResultStatus NAX::Parse(std::string path) {
Loader::ResultStatus NAX::Parse(std::string_view path) {
if (file->ReadObject(header.get()) != sizeof(NAXHeader))
return Loader::ResultStatus::ErrorBadNAXHeader;
if (header->magic != Common::MakeMagic('N', 'A', 'X', '0'))
return Loader::ResultStatus::ErrorBadNAXHeader;
if (file->GetSize() < 0x4000 + header->file_size)
if (file->GetSize() < NAX_HEADER_PADDING_SIZE + header->file_size)
return Loader::ResultStatus::ErrorIncorrectNAXFileSize;
keys.DeriveSDSeedLazy();
@ -87,14 +89,14 @@ Loader::ResultStatus NAX::Parse(std::string path) {
const auto enc_keys = header->key_area;
size_t i = 0;
for (; i < 2; ++i) {
for (; i < sd_keys.size(); ++i) {
std::array<Core::Crypto::Key128, 2> nax_keys{};
if (!CalculateHMAC256(nax_keys.data(), sd_keys[i].data(), 0x10, path.c_str(),
if (!CalculateHMAC256(nax_keys.data(), sd_keys[i].data(), 0x10, std::string(path).c_str(),
path.size())) {
return Loader::ResultStatus::ErrorNAXKeyHMACFailed;
}
for (size_t j = 0; j < 2; ++j) {
for (size_t j = 0; j < nax_keys.size(); ++j) {
Core::Crypto::AESCipher<Core::Crypto::Key128> cipher(nax_keys[j],
Core::Crypto::Mode::ECB);
cipher.Transcode(enc_keys[j].data(), 0x10, header->key_area[j].data(),
@ -117,28 +119,29 @@ Loader::ResultStatus NAX::Parse(std::string path) {
type = static_cast<NAXContentType>(i);
Core::Crypto::Key256 final_key{};
memcpy(final_key.data(), &header->key_area, 0x20);
const auto enc_file = std::make_shared<OffsetVfsFile>(file, header->file_size, 0x4000);
std::memcpy(final_key.data(), &header->key_area, final_key.size());
const auto enc_file =
std::make_shared<OffsetVfsFile>(file, header->file_size, NAX_HEADER_PADDING_SIZE);
dec_file = std::make_shared<Core::Crypto::XTSEncryptionLayer>(enc_file, final_key);
return Loader::ResultStatus::Success;
}
Loader::ResultStatus NAX::GetStatus() {
Loader::ResultStatus NAX::GetStatus() const {
return status;
}
VirtualFile NAX::GetDecrypted() {
VirtualFile NAX::GetDecrypted() const {
return dec_file;
}
std::shared_ptr<NCA> NAX::AsNCA() {
std::shared_ptr<NCA> NAX::AsNCA() const {
if (type == NAXContentType::NCA)
return std::make_shared<NCA>(GetDecrypted());
return nullptr;
}
NAXContentType NAX::GetContentType() {
NAXContentType NAX::GetContentType() const {
return type;
}

10
src/core/file_sys/xts_archive.h
View File

@ -33,13 +33,13 @@ public:
explicit NAX(VirtualFile file);
explicit NAX(VirtualFile file, std::array<u8, 0x10> nca_id);
Loader::ResultStatus GetStatus();
Loader::ResultStatus GetStatus() const;
VirtualFile GetDecrypted();
VirtualFile GetDecrypted() const;
std::shared_ptr<NCA> AsNCA();
std::shared_ptr<NCA> AsNCA() const;
NAXContentType GetContentType();
NAXContentType GetContentType() const;
std::vector<std::shared_ptr<VfsFile>> GetFiles() const override;
@ -53,7 +53,7 @@ protected:
bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
private:
Loader::ResultStatus Parse(std::string path);
Loader::ResultStatus Parse(std::string_view path);
std::unique_ptr<NAXHeader> header;

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