ncch_container: support encrypted games

src/core/CMakeLists.txt

@@ -64,6 +64,8 @@ add_library(core STATIC
     file_sys/ncch_container.h
     file_sys/path_parser.cpp
     file_sys/path_parser.h
+    file_sys/romfs_reader.cpp
+    file_sys/romfs_reader.h
     file_sys/savedata_archive.cpp
     file_sys/savedata_archive.h
     file_sys/title_metadata.cpp

src/core/file_sys/archive_ncch.cpp

@@ -74,14 +74,11 @@ ResultVal<std::unique_ptr<FileBackend>> NCCHArchive::OpenFile(const Path& path,
     // NCCH RomFS
     NCCHFilePathType filepath_type = static_cast<NCCHFilePathType>(openfile_path.filepath_type);
     if (filepath_type == NCCHFilePathType::RomFS) {
-        std::shared_ptr<FileUtil::IOFile> romfs_file;
+        std::shared_ptr<RomFSReader> romfs_file;
-        u64 romfs_offset = 0;
-        u64 romfs_size = 0;
 
-        result = ncch_container.ReadRomFS(romfs_file, romfs_offset, romfs_size);
+        result = ncch_container.ReadRomFS(romfs_file);
         std::unique_ptr<DelayGenerator> delay_generator = std::make_unique<RomFSDelayGenerator>();
-        file = std::make_unique<IVFCFile>(std::move(romfs_file), romfs_offset, romfs_size,
+        file = std::make_unique<IVFCFile>(std::move(romfs_file), std::move(delay_generator));
-                                          std::move(delay_generator));
     } else if (filepath_type == NCCHFilePathType::Code ||
                filepath_type == NCCHFilePathType::ExeFS) {
         std::vector<u8> buffer;

src/core/file_sys/archive_selfncch.cpp

@@ -174,8 +174,7 @@ private:
             std::unique_ptr<DelayGenerator> delay_generator =
                 std::make_unique<RomFSDelayGenerator>();
             return MakeResult<std::unique_ptr<FileBackend>>(
-                std::make_unique<IVFCFile>(ncch_data.romfs_file, ncch_data.romfs_offset,
+                std::make_unique<IVFCFile>(ncch_data.romfs_file, std::move(delay_generator)));
-                                           ncch_data.romfs_size, std::move(delay_generator)));
         } else {
             LOG_INFO(Service_FS, "Unable to read RomFS");
             return ERROR_ROMFS_NOT_FOUND;
@@ -187,8 +186,7 @@ private:
             std::unique_ptr<DelayGenerator> delay_generator =
                 std::make_unique<RomFSDelayGenerator>();
             return MakeResult<std::unique_ptr<FileBackend>>(std::make_unique<IVFCFile>(
-                ncch_data.update_romfs_file, ncch_data.update_romfs_offset,
+                ncch_data.update_romfs_file, std::move(delay_generator)));
-                ncch_data.update_romfs_size, std::move(delay_generator)));
         } else {
             LOG_INFO(Service_FS, "Unable to read update RomFS");
             return ERROR_ROMFS_NOT_FOUND;
@@ -252,17 +250,14 @@ void ArchiveFactory_SelfNCCH::Register(Loader::AppLoader& app_loader) {
 
     NCCHData& data = ncch_data[program_id];
 
-    std::shared_ptr<FileUtil::IOFile> romfs_file_;
+    std::shared_ptr<RomFSReader> romfs_file_;
-    if (Loader::ResultStatus::Success ==
+    if (Loader::ResultStatus::Success == app_loader.ReadRomFS(romfs_file_)) {
-        app_loader.ReadRomFS(romfs_file_, data.romfs_offset, data.romfs_size)) {
 
         data.romfs_file = std::move(romfs_file_);
     }
 
-    std::shared_ptr<FileUtil::IOFile> update_romfs_file;
+    std::shared_ptr<RomFSReader> update_romfs_file;
-    if (Loader::ResultStatus::Success == app_loader.ReadUpdateRomFS(update_romfs_file,
+    if (Loader::ResultStatus::Success == app_loader.ReadUpdateRomFS(update_romfs_file)) {
-                                                                    data.update_romfs_offset,
-                                                                    data.update_romfs_size)) {
 
         data.update_romfs_file = std::move(update_romfs_file);
     }

src/core/file_sys/archive_selfncch.h

@@ -22,13 +22,8 @@ struct NCCHData {
     std::shared_ptr<std::vector<u8>> icon;
     std::shared_ptr<std::vector<u8>> logo;
     std::shared_ptr<std::vector<u8>> banner;
-    std::shared_ptr<FileUtil::IOFile> romfs_file;
+    std::shared_ptr<RomFSReader> romfs_file;
-    u64 romfs_offset = 0;
+    std::shared_ptr<RomFSReader> update_romfs_file;
-    u64 romfs_size = 0;
-
-    std::shared_ptr<FileUtil::IOFile> update_romfs_file;
-    u64 update_romfs_offset = 0;
-    u64 update_romfs_size = 0;
 };
 
 /// File system interface to the SelfNCCH archive

src/core/file_sys/ivfc_archive.cpp

@@ -14,8 +14,7 @@
 
 namespace FileSys {
 
-IVFCArchive::IVFCArchive(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size)
+IVFCArchive::IVFCArchive(std::shared_ptr<RomFSReader> file) : romfs_file(std::move(file)) {}
-    : romfs_file(std::move(file)), data_offset(offset), data_size(size) {}
 
 std::string IVFCArchive::GetName() const {
     return "IVFC";
@@ -25,7 +24,7 @@ ResultVal<std::unique_ptr<FileBackend>> IVFCArchive::OpenFile(const Path& path,
                                                               const Mode& mode) const {
     std::unique_ptr<DelayGenerator> delay_generator = std::make_unique<IVFCDelayGenerator>();
     return MakeResult<std::unique_ptr<FileBackend>>(
-        std::make_unique<IVFCFile>(romfs_file, data_offset, data_size, std::move(delay_generator)));
+        std::make_unique<IVFCFile>(romfs_file, std::move(delay_generator)));
 }
 
 ResultCode IVFCArchive::DeleteFile(const Path& path) const {
@@ -85,18 +84,15 @@ u64 IVFCArchive::GetFreeBytes() const {
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-IVFCFile::IVFCFile(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size,
+IVFCFile::IVFCFile(std::shared_ptr<RomFSReader> file,
                    std::unique_ptr<DelayGenerator> delay_generator_)
-    : romfs_file(std::move(file)), data_offset(offset), data_size(size) {
+    : romfs_file(std::move(file)) {
     delay_generator = std::move(delay_generator_);
 }
 
 ResultVal<size_t> IVFCFile::Read(const u64 offset, const size_t length, u8* buffer) const {
     LOG_TRACE(Service_FS, "called offset={}, length={}", offset, length);
-    romfs_file->Seek(data_offset + offset, SEEK_SET);
+    return MakeResult<size_t>(romfs_file->ReadFile(offset, length, buffer));
-    size_t read_length = (size_t)std::min((u64)length, data_size - offset);
-
-    return MakeResult<size_t>(romfs_file->ReadBytes(buffer, read_length));
 }
 
 ResultVal<size_t> IVFCFile::Write(const u64 offset, const size_t length, const bool flush,
@@ -107,7 +103,7 @@ ResultVal<size_t> IVFCFile::Write(const u64 offset, const size_t length, const b
 }
 
 u64 IVFCFile::GetSize() const {
-    return data_size;
+    return romfs_file->GetSize();
 }
 
 bool IVFCFile::SetSize(const u64 size) const {

src/core/file_sys/ivfc_archive.h

@@ -13,6 +13,7 @@
 #include "core/file_sys/archive_backend.h"
 #include "core/file_sys/directory_backend.h"
 #include "core/file_sys/file_backend.h"
+#include "core/file_sys/romfs_reader.h"
 #include "core/hle/result.h"
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -67,7 +68,7 @@ public:
  */
 class IVFCArchive : public ArchiveBackend {
 public:
-    IVFCArchive(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size);
+    IVFCArchive(std::shared_ptr<RomFSReader> file);
 
     std::string GetName() const override;
 
@@ -84,15 +85,12 @@ public:
     u64 GetFreeBytes() const override;
 
 protected:
-    std::shared_ptr<FileUtil::IOFile> romfs_file;
+    std::shared_ptr<RomFSReader> romfs_file;
-    u64 data_offset;
-    u64 data_size;
 };
 
 class IVFCFile : public FileBackend {
 public:
-    IVFCFile(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size,
+    IVFCFile(std::shared_ptr<RomFSReader> file, std::unique_ptr<DelayGenerator> delay_generator_);
-             std::unique_ptr<DelayGenerator> delay_generator_);
 
     ResultVal<size_t> Read(u64 offset, size_t length, u8* buffer) const override;
     ResultVal<size_t> Write(u64 offset, size_t length, bool flush, const u8* buffer) override;
@@ -104,9 +102,7 @@ public:
     void Flush() const override {}
 
 private:
-    std::shared_ptr<FileUtil::IOFile> romfs_file;
+    std::shared_ptr<RomFSReader> romfs_file;
-    u64 data_offset;
-    u64 data_size;
 };
 
 class IVFCDirectory : public DirectoryBackend {

src/core/file_sys/ncch_container.cpp

@@ -5,10 +5,13 @@
 #include <cinttypes>
 #include <cstring>
 #include <memory>
+#include <cryptopp/aes.h>
+#include <cryptopp/modes.h>
 #include "common/common_types.h"
 #include "common/logging/log.h"
 #include "core/core.h"
 #include "core/file_sys/ncch_container.h"
+#include "core/hw/aes/key.h"
 #include "core/loader/loader.h"
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -142,6 +145,116 @@ Loader::ResultStatus NCCHContainer::Load() {
             return Loader::ResultStatus::ErrorInvalidFormat;
 
         has_header = true;
+        bool failed_to_decrypt = false;
+        if (!ncch_header.no_crypto) {
+            is_encrypted = true;
+
+            // Find primary and secondary keys
+            if (ncch_header.fixed_key) {
+                LOG_DEBUG(Service_FS, "Fixed-key crypto");
+                primary_key.fill(0);
+                secondary_key.fill(0);
+            } else {
+                using namespace HW::AES;
+                InitKeys();
+                std::array<u8, 16> key_y_primary, key_y_secondary;
+
+                std::copy(ncch_header.signature, ncch_header.signature + key_y_primary.size(),
+                          key_y_primary.begin());
+
+                if (!ncch_header.seed_crypto) {
+                    key_y_secondary = key_y_primary;
+                } else {
+                    // Seed crypto is unimplemented.
+                    LOG_ERROR(Service_FS, "Unsupported seed crypto");
+                    failed_to_decrypt = true;
+                }
+
+                SetKeyY(KeySlotID::NCCHSecure1, key_y_primary);
+                if (!IsNormalKeyAvailable(KeySlotID::NCCHSecure1)) {
+                    LOG_ERROR(Service_FS, "Secure1 KeyX missing");
+                    failed_to_decrypt = true;
+                }
+                primary_key = GetNormalKey(KeySlotID::NCCHSecure1);
+
+                switch (ncch_header.secondary_key_slot) {
+                case 0:
+                    LOG_DEBUG(Service_FS, "Secure1 crypto");
+                    secondary_key = primary_key;
+                    break;
+                case 1:
+                    LOG_DEBUG(Service_FS, "Secure2 crypto");
+                    SetKeyY(KeySlotID::NCCHSecure2, key_y_secondary);
+                    if (!IsNormalKeyAvailable(KeySlotID::NCCHSecure2)) {
+                        LOG_ERROR(Service_FS, "Secure2 KeyX missing");
+                        failed_to_decrypt = true;
+                    }
+                    secondary_key = GetNormalKey(KeySlotID::NCCHSecure2);
+                    break;
+                case 10:
+                    LOG_DEBUG(Service_FS, "Secure3 crypto");
+                    SetKeyY(KeySlotID::NCCHSecure3, key_y_secondary);
+                    if (!IsNormalKeyAvailable(KeySlotID::NCCHSecure3)) {
+                        LOG_ERROR(Service_FS, "Secure3 KeyX missing");
+                        failed_to_decrypt = true;
+                    }
+                    secondary_key = GetNormalKey(KeySlotID::NCCHSecure3);
+                    break;
+                case 11:
+                    LOG_DEBUG(Service_FS, "Secure4 crypto");
+                    SetKeyY(KeySlotID::NCCHSecure4, key_y_secondary);
+                    if (!IsNormalKeyAvailable(KeySlotID::NCCHSecure4)) {
+                        LOG_ERROR(Service_FS, "Secure4 KeyX missing");
+                        failed_to_decrypt = true;
+                    }
+                    secondary_key = GetNormalKey(KeySlotID::NCCHSecure4);
+                    break;
+                }
+            }
+
+            // Find CTR for each section
+            // Written with reference to
+            // https://github.com/d0k3/GodMode9/blob/99af6a73be48fa7872649aaa7456136da0df7938/arm9/source/game/ncch.c#L34-L52
+            if (ncch_header.version == 0 || ncch_header.version == 2) {
+                LOG_DEBUG(Loader, "NCCH version 0/2");
+                // In this version, CTR for each section is a magic number prefixed by partition ID
+                // (reverse order)
+                std::reverse_copy(ncch_header.partition_id, ncch_header.partition_id + 8,
+                                  exheader_ctr.begin());
+                exefs_ctr = romfs_ctr = exheader_ctr;
+                exheader_ctr[8] = 1;
+                exefs_ctr[8] = 2;
+                romfs_ctr[8] = 3;
+            } else if (ncch_header.version == 1) {
+                LOG_DEBUG(Loader, "NCCH version 1");
+                // In this version, CTR for each section is the section offset prefixed by partition
+                // ID, as if the entire NCCH image is encrypted using a single CTR stream.
+                std::copy(ncch_header.partition_id, ncch_header.partition_id + 8,
+                          exheader_ctr.begin());
+                exefs_ctr = romfs_ctr = exheader_ctr;
+                auto u32ToBEArray = [](u32 value) -> std::array<u8, 4> {
+                    return std::array<u8, 4>{
+                        static_cast<u8>(value >> 24),
+                        static_cast<u8>((value >> 16) & 0xFF),
+                        static_cast<u8>((value >> 8) & 0xFF),
+                        static_cast<u8>(value & 0xFF),
+                    };
+                };
+                auto offset_exheader = u32ToBEArray(0x200); // exheader offset
+                auto offset_exefs = u32ToBEArray(ncch_header.exefs_offset * kBlockSize);
+                auto offset_romfs = u32ToBEArray(ncch_header.romfs_offset * kBlockSize);
+                std::copy(offset_exheader.begin(), offset_exheader.end(),
+                          exheader_ctr.begin() + 12);
+                std::copy(offset_exefs.begin(), offset_exefs.end(), exefs_ctr.begin() + 12);
+                std::copy(offset_romfs.begin(), offset_romfs.end(), romfs_ctr.begin() + 12);
+            } else {
+                LOG_ERROR(Service_FS, "Unknown NCCH version {}", ncch_header.version);
+                failed_to_decrypt = true;
+            }
+        } else {
+            LOG_DEBUG(Service_FS, "No crypto");
+            is_encrypted = false;
+        }
 
         // System archives and DLC don't have an extended header but have RomFS
         if (ncch_header.extended_header_size) {
@@ -149,6 +262,26 @@ Loader::ResultStatus NCCHContainer::Load() {
                 sizeof(ExHeader_Header))
                 return Loader::ResultStatus::Error;
 
+            if (is_encrypted) {
+                // This ID check is masked to low 32-bit as a toleration to ill-formed ROM created
+                // by merging games and its updates.
+                if ((exheader_header.system_info.jump_id & 0xFFFFFFFF) ==
+                    (ncch_header.program_id & 0xFFFFFFFF)) {
+                    LOG_WARNING(Service_FS, "NCCH is marked as encrypted but with decrypted "
+                                            "exheader. Force no crypto scheme.");
+                    is_encrypted = false;
+                } else {
+                    if (failed_to_decrypt) {
+                        LOG_ERROR(Service_FS, "Failed to decrypt");
+                        return Loader::ResultStatus::ErrorEncrypted;
+                    }
+                    CryptoPP::byte* data = reinterpret_cast<CryptoPP::byte*>(&exheader_header);
+                    CryptoPP::CTR_Mode<CryptoPP::AES>::Decryption(
+                        primary_key.data(), primary_key.size(), exheader_ctr.data())
+                        .ProcessData(data, data, sizeof(exheader_header));
+                }
+            }
+
             is_compressed = (exheader_header.codeset_info.flags.flag & 1) == 1;
             u32 entry_point = exheader_header.codeset_info.text.address;
             u32 code_size = exheader_header.codeset_info.text.code_size;
@@ -173,12 +306,6 @@ Loader::ResultStatus NCCHContainer::Load() {
             LOG_DEBUG(Service_FS, "System Mode:                 {}",
                       static_cast<int>(exheader_header.arm11_system_local_caps.system_mode));
 
-            if (exheader_header.system_info.jump_id != ncch_header.program_id) {
-                LOG_ERROR(Service_FS,
-                          "ExHeader Program ID mismatch: the ROM is probably encrypted.");
-                return Loader::ResultStatus::ErrorEncrypted;
-            }
-
             has_exheader = true;
         }
 
@@ -194,6 +321,13 @@ Loader::ResultStatus NCCHContainer::Load() {
             if (file.ReadBytes(&exefs_header, sizeof(ExeFs_Header)) != sizeof(ExeFs_Header))
                 return Loader::ResultStatus::Error;
 
+            if (is_encrypted) {
+                CryptoPP::byte* data = reinterpret_cast<CryptoPP::byte*>(&exefs_header);
+                CryptoPP::CTR_Mode<CryptoPP::AES>::Decryption(primary_key.data(),
+                                                              primary_key.size(), exefs_ctr.data())
+                    .ProcessData(data, data, sizeof(exefs_header));
+            }
+
             exefs_file = FileUtil::IOFile(filepath, "rb");
             has_exefs = true;
         }
@@ -293,6 +427,17 @@ Loader::ResultStatus NCCHContainer::LoadSectionExeFS(const char* name, std::vect
                 (section.offset + exefs_offset + sizeof(ExeFs_Header) + ncch_offset);
             exefs_file.Seek(section_offset, SEEK_SET);
 
+            std::array<u8, 16> key;
+            if (strcmp(section.name, "icon") == 0 || strcmp(section.name, "banner") == 0) {
+                key = primary_key;
+            } else {
+                key = secondary_key;
+            }
+
+            CryptoPP::CTR_Mode<CryptoPP::AES>::Decryption dec(key.data(), key.size(),
+                                                              exefs_ctr.data());
+            dec.Seek(section.offset + sizeof(ExeFs_Header));
+
             if (strcmp(section.name, ".code") == 0 && is_compressed) {
                 // Section is compressed, read compressed .code section...
                 std::unique_ptr<u8[]> temp_buffer;
@@ -305,6 +450,10 @@ Loader::ResultStatus NCCHContainer::LoadSectionExeFS(const char* name, std::vect
                 if (exefs_file.ReadBytes(&temp_buffer[0], section.size) != section.size)
                     return Loader::ResultStatus::Error;
 
+                if (is_encrypted) {
+                    dec.ProcessData(&temp_buffer[0], &temp_buffer[0], section.size);
+                }
+
                 // Decompress .code section...
                 u32 decompressed_size = LZSS_GetDecompressedSize(&temp_buffer[0], section.size);
                 buffer.resize(decompressed_size);
@@ -315,6 +464,9 @@ Loader::ResultStatus NCCHContainer::LoadSectionExeFS(const char* name, std::vect
                 buffer.resize(section.size);
                 if (exefs_file.ReadBytes(&buffer[0], section.size) != section.size)
                     return Loader::ResultStatus::Error;
+                if (is_encrypted) {
+                    dec.ProcessData(&buffer[0], &buffer[0], section.size);
+                }
             }
             return Loader::ResultStatus::Success;
         }
@@ -354,13 +506,12 @@ Loader::ResultStatus NCCHContainer::LoadOverrideExeFSSection(const char* name,
     return Loader::ResultStatus::ErrorNotUsed;
 }
 
-Loader::ResultStatus NCCHContainer::ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file,
+Loader::ResultStatus NCCHContainer::ReadRomFS(std::shared_ptr<RomFSReader>& romfs_file) {
-                                              u64& offset, u64& size) {
     Loader::ResultStatus result = Load();
     if (result != Loader::ResultStatus::Success)
         return result;
 
-    if (ReadOverrideRomFS(romfs_file, offset, size) == Loader::ResultStatus::Success)
+    if (ReadOverrideRomFS(romfs_file) == Loader::ResultStatus::Success)
         return Loader::ResultStatus::Success;
 
     if (!has_romfs) {
@@ -381,26 +532,30 @@ Loader::ResultStatus NCCHContainer::ReadRomFS(std::shared_ptr<FileUtil::IOFile>&
         return Loader::ResultStatus::Error;
 
     // We reopen the file, to allow its position to be independent from file's
-    romfs_file = std::make_shared<FileUtil::IOFile>(filepath, "rb");
+    FileUtil::IOFile romfs_file_inner(filepath, "rb");
-    if (!romfs_file->IsOpen())
+    if (!romfs_file_inner.IsOpen())
         return Loader::ResultStatus::Error;
 
-    offset = romfs_offset;
+    if (is_encrypted) {
-    size = romfs_size;
+        romfs_file = std::make_shared<RomFSReader>(std::move(romfs_file_inner), romfs_offset,
+                                                   romfs_size, secondary_key, romfs_ctr, 0x1000);
+    } else {
+        romfs_file =
+            std::make_shared<RomFSReader>(std::move(romfs_file_inner), romfs_offset, romfs_size);
+    }
 
     return Loader::ResultStatus::Success;
 }
 
-Loader::ResultStatus NCCHContainer::ReadOverrideRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file,
+Loader::ResultStatus NCCHContainer::ReadOverrideRomFS(std::shared_ptr<RomFSReader>& romfs_file) {
-                                                      u64& offset, u64& size) {
     // Check for RomFS overrides
     std::string split_filepath = filepath + ".romfs";
     if (FileUtil::Exists(split_filepath)) {
-        romfs_file = std::make_shared<FileUtil::IOFile>(split_filepath, "rb");
+        FileUtil::IOFile romfs_file_inner(split_filepath, "rb");
-        if (romfs_file->IsOpen()) {
+        if (romfs_file_inner.IsOpen()) {
             LOG_WARNING(Service_FS, "File {} overriding built-in RomFS", split_filepath);
-            offset = 0;
+            romfs_file = std::make_shared<RomFSReader>(std::move(romfs_file_inner), 0,
-            size = romfs_file->GetSize();
+                                                       romfs_file_inner.GetSize());
             return Loader::ResultStatus::Success;
         }
     }

src/core/file_sys/ncch_container.h

@@ -13,6 +13,7 @@
 #include "common/file_util.h"
 #include "common/swap.h"
 #include "core/core.h"
+#include "core/file_sys/romfs_reader.h"
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 /// NCCH header (Note: "NCCH" appears to be a publicly unknown acronym)
@@ -32,7 +33,28 @@ struct NCCH_Header {
     u8 extended_header_hash[0x20];
     u32_le extended_header_size;
     u8 reserved_2[4];
-    u8 flags[8];
+    u8 reserved_flag[3];
+    u8 secondary_key_slot;
+    u8 platform;
+    enum class ContentType : u8 {
+        Application = 0,
+        SystemUpdate = 1,
+        Manual = 2,
+        Child = 3,
+        Trial = 4,
+    };
+    union {
+        BitField<0, 1, u8> is_data;
+        BitField<1, 1, u8> is_executable;
+        BitField<2, 3, ContentType> content_type;
+    };
+    u8 content_unit_size;
+    union {
+        BitField<0, 1, u8> fixed_key;
+        BitField<1, 1, u8> no_romfs;
+        BitField<2, 1, u8> no_crypto;
+        BitField<5, 1, u8> seed_crypto;
+    };
     u32_le plain_region_offset;
     u32_le plain_region_size;
     u32_le logo_region_offset;
@@ -211,8 +233,7 @@ public:
      * @param size The size of the romfs
      * @return ResultStatus result of function
      */
-    Loader::ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
+    Loader::ResultStatus ReadRomFS(std::shared_ptr<RomFSReader>& romfs_file);
-                                   u64& size);
 
     /**
      * Get the override RomFS of the NCCH container
@@ -222,8 +243,7 @@ public:
      * @param size The size of the romfs
      * @return ResultStatus result of function
      */
-    Loader::ResultStatus ReadOverrideRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file,
+    Loader::ResultStatus ReadOverrideRomFS(std::shared_ptr<RomFSReader>& romfs_file);
-                                           u64& offset, u64& size);
 
     /**
      * Get the Program ID of the NCCH container
@@ -263,6 +283,14 @@ private:
     bool is_loaded = false;
     bool is_compressed = false;
 
+    bool is_encrypted = false;
+    // for decrypting exheader, exefs header and icon/banner section
+    std::array<u8, 16> primary_key{};
+    std::array<u8, 16> secondary_key{}; // for decrypting romfs and .code section
+    std::array<u8, 16> exheader_ctr{};
+    std::array<u8, 16> exefs_ctr{};
+    std::array<u8, 16> romfs_ctr{};
+
     u32 ncch_offset = 0; // Offset to NCCH header, can be 0 for NCCHs or non-zero for CIAs/NCSDs
     u32 exefs_offset = 0;
 

src/core/file_sys/romfs_reader.cpp

@@ -0,0 +1,22 @@
+#include <algorithm>
+#include <cryptopp/aes.h>
+#include <cryptopp/modes.h>
+#include "core/file_sys/romfs_reader.h"
+
+namespace FileSys {
+
+std::size_t RomFSReader::ReadFile(std::size_t offset, std::size_t length, u8* buffer) {
+    if (length == 0)
+        return 0; // Crypto++ does not like zero size buffer
+    file.Seek(file_offset + offset, SEEK_SET);
+    std::size_t read_length = std::min(length, data_size - offset);
+    read_length = file.ReadBytes(buffer, read_length);
+    if (is_encrypted) {
+        CryptoPP::CTR_Mode<CryptoPP::AES>::Decryption d(key.data(), key.size(), ctr.data());
+        d.Seek(crypto_offset + offset);
+        d.ProcessData(buffer, buffer, read_length);
+    }
+    return read_length;
+}
+
+} // namespace FileSys

src/core/file_sys/romfs_reader.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <array>
+#include "common/common_types.h"
+#include "common/file_util.h"
+
+namespace FileSys {
+
+class RomFSReader {
+public:
+    RomFSReader(FileUtil::IOFile&& file, std::size_t file_offset, std::size_t data_size)
+        : is_encrypted(false), file(std::move(file)), file_offset(file_offset),
+          data_size(data_size) {}
+
+    RomFSReader(FileUtil::IOFile&& file, std::size_t file_offset, std::size_t data_size,
+                const std::array<u8, 16>& key, const std::array<u8, 16>& ctr,
+                std::size_t crypto_offset)
+        : is_encrypted(true), file(std::move(file)), key(key), ctr(ctr), file_offset(file_offset),
+          crypto_offset(crypto_offset), data_size(data_size) {}
+
+    std::size_t GetSize() const {
+        return data_size;
+    }
+
+    std::size_t ReadFile(std::size_t offset, std::size_t length, u8* buffer);
+
+private:
+    bool is_encrypted;
+    FileUtil::IOFile file;
+    std::array<u8, 16> key;
+    std::array<u8, 16> ctr;
+    std::size_t file_offset;
+    std::size_t crypto_offset;
+    std::size_t data_size;
+};
+
+} // namespace FileSys

src/core/hw/aes/key.cpp

@@ -56,13 +56,6 @@ struct KeySlot {
 
 std::array<KeySlot, KeySlotID::MaxKeySlotID> key_slots;
 
-void ClearAllKeys() {
-    for (KeySlot& slot : key_slots) {
-        slot.Clear();
-    }
-    generator_constant.reset();
-}
-
 AESKey HexToKey(const std::string& hex) {
     if (hex.size() < 32) {
         throw std::invalid_argument("hex string is too short");
@@ -141,8 +134,11 @@ void LoadPresetKeys() {
 } // namespace
 
 void InitKeys() {
-    ClearAllKeys();
+    static bool initialized = false;
+    if (initialized)
+        return;
     LoadPresetKeys();
+    initialized = true;
 }
 
 void SetGeneratorConstant(const AESKey& key) {

src/core/hw/aes/key.h

@@ -12,8 +12,16 @@ namespace HW {
 namespace AES {
 
 enum KeySlotID : size_t {
-    // AES Keyslot used to generate the UDS data frame CCMP key.
+    // AES keyslots used to decrypt NCCH
+    NCCHSecure1 = 0x2C,
+    NCCHSecure2 = 0x25,
+    NCCHSecure3 = 0x18,
+    NCCHSecure4 = 0x1B,
+
+    // AES keyslot used to generate the UDS data frame CCMP key.
     UDSDataKey = 0x2D,
+
+    // AES keyslot used for APT:Wrap/Unwrap functions
     APTWrap = 0x31,
 
     MaxKeySlotID = 0x40,

src/core/loader/3dsx.cpp

@@ -283,8 +283,7 @@ ResultStatus AppLoader_THREEDSX::Load(Kernel::SharedPtr<Kernel::Process>& proces
     return ResultStatus::Success;
 }
 
-ResultStatus AppLoader_THREEDSX::ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file,
+ResultStatus AppLoader_THREEDSX::ReadRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) {
-                                           u64& offset, u64& size) {
     if (!file.IsOpen())
         return ResultStatus::Error;
 
@@ -307,12 +306,12 @@ ResultStatus AppLoader_THREEDSX::ReadRomFS(std::shared_ptr<FileUtil::IOFile>& ro
         LOG_DEBUG(Loader, "RomFS size:             {:#010X}", romfs_size);
 
         // We reopen the file, to allow its position to be independent from file's
-        romfs_file = std::make_shared<FileUtil::IOFile>(filepath, "rb");
+        FileUtil::IOFile romfs_file_inner(filepath, "rb");
-        if (!romfs_file->IsOpen())
+        if (!romfs_file_inner.IsOpen())
             return ResultStatus::Error;
 
-        offset = romfs_offset;
+        romfs_file = std::make_shared<FileSys::RomFSReader>(std::move(romfs_file_inner),
-        size = romfs_size;
+                                                            romfs_offset, romfs_size);
 
         return ResultStatus::Success;
     }

src/core/loader/3dsx.h

@@ -35,8 +35,7 @@ public:
 
     ResultStatus ReadIcon(std::vector<u8>& buffer) override;
 
-    ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
+    ResultStatus ReadRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) override;
-                           u64& size) override;
 
 private:
     std::string filename;

src/core/loader/loader.h

@@ -13,6 +13,7 @@
 #include <boost/optional.hpp>
 #include "common/common_types.h"
 #include "common/file_util.h"
+#include "core/file_sys/romfs_reader.h"
 #include "core/hle/kernel/kernel.h"
 
 namespace Kernel {
@@ -160,12 +161,9 @@ public:
      * Get the RomFS of the application
      * Since the RomFS can be huge, we return a file reference instead of copying to a buffer
      * @param romfs_file The file containing the RomFS
-     * @param offset The offset the romfs begins on
-     * @param size The size of the romfs
      * @return ResultStatus result of function
      */
-    virtual ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
+    virtual ResultStatus ReadRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) {
-                                   u64& size) {
         return ResultStatus::ErrorNotImplemented;
     }
 
@@ -173,12 +171,9 @@ public:
      * Get the update RomFS of the application
      * Since the RomFS can be huge, we return a file reference instead of copying to a buffer
      * @param romfs_file The file containing the RomFS
-     * @param offset The offset the romfs begins on
-     * @param size The size of the romfs
      * @return ResultStatus result of function
      */
-    virtual ResultStatus ReadUpdateRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
+    virtual ResultStatus ReadUpdateRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) {
-                                         u64& size) {
         return ResultStatus::ErrorNotImplemented;
     }
 

src/core/loader/ncch.cpp

@@ -211,17 +211,15 @@ ResultStatus AppLoader_NCCH::ReadProgramId(u64& out_program_id) {
     return ResultStatus::Success;
 }
 
-ResultStatus AppLoader_NCCH::ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
+ResultStatus AppLoader_NCCH::ReadRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) {
-                                       u64& size) {
+    return base_ncch.ReadRomFS(romfs_file);
-    return base_ncch.ReadRomFS(romfs_file, offset, size);
 }
 
-ResultStatus AppLoader_NCCH::ReadUpdateRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file,
+ResultStatus AppLoader_NCCH::ReadUpdateRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) {
-                                             u64& offset, u64& size) {
+    ResultStatus result = update_ncch.ReadRomFS(romfs_file);
-    ResultStatus result = update_ncch.ReadRomFS(romfs_file, offset, size);
 
     if (result != ResultStatus::Success)
-        return base_ncch.ReadRomFS(romfs_file, offset, size);
+        return base_ncch.ReadRomFS(romfs_file);
 
     return ResultStatus::Success;
 }

src/core/loader/ncch.h

@@ -51,11 +51,9 @@ public:
 
     ResultStatus ReadProgramId(u64& out_program_id) override;
 
-    ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
+    ResultStatus ReadRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) override;
-                           u64& size) override;
 
-    ResultStatus ReadUpdateRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
+    ResultStatus ReadUpdateRomFS(std::shared_ptr<FileSys::RomFSReader>& romfs_file) override;
-                                 u64& size) override;
 
     ResultStatus ReadTitle(std::string& title) override;