Load keys from new3DS native firm

src/common/common_paths.h

@@ -51,3 +51,4 @@
 #define SHARED_FONT "shared_font.bin"
 #define AES_KEYS "aes_keys.txt"
 #define BOOTROM9 "boot9.bin"
+#define SECRET_SECTOR "sector0x96.bin"

src/core/hw/aes/key.cpp

@@ -6,6 +6,8 @@
 #include <exception>
 #include <optional>
 #include <sstream>
+#include <cryptopp/aes.h>
+#include <cryptopp/modes.h>
 #include <fmt/format.h>
 #include "common/common_paths.h"
 #include "common/file_util.h"
@@ -37,6 +39,19 @@ struct KeyDesc {
     bool same_as_before;
 };
 
+AESKey HexToKey(const std::string& hex) {
+    if (hex.size() < 32) {
+        throw std::invalid_argument("hex string is too short");
+    }
+
+    AESKey key;
+    for (std::size_t i = 0; i < key.size(); ++i) {
+        key[i] = static_cast<u8>(std::stoi(hex.substr(i * 2, 2), 0, 16));
+    }
+
+    return key;
+}
+
 struct KeySlot {
     std::optional<AESKey> x;
     std::optional<AESKey> y;
@@ -74,18 +89,39 @@ struct KeySlot {
 std::array<KeySlot, KeySlotID::MaxKeySlotID> key_slots;
 std::array<std::optional<AESKey>, 6> common_key_y_slots;
 
-AESKey HexToKey(const std::string& hex) {
+enum class FirmwareType : u32 {
-    if (hex.size() < 32) {
+    ARM9 = 0,  // uses NDMA
-        throw std::invalid_argument("hex string is too short");
+    ARM11 = 1, // uses XDMA
-    }
+};
 
-    AESKey key;
+struct FirmwareSectionHeader {
-    for (std::size_t i = 0; i < key.size(); ++i) {
+    u32_le offset;
-        key[i] = static_cast<u8>(std::stoi(hex.substr(i * 2, 2), 0, 16));
+    u32_le phys_address;
-    }
+    u32_le size;
+    enum_le<FirmwareType> firmware_type;
+    std::array<u8, 0x20> hash; // SHA-256 hash
+};
 
-    return key;
+struct FIRM_Header {
-}
+    u32_le magic;         // FIRM
+    u32_le boot_priority; // Usually 0
+    u32_le arm11_entrypoint;
+    u32_le arm9_entrypoint;
+    INSERT_PADDING_BYTES(0x30);                           // Reserved
+    std::array<FirmwareSectionHeader, 4> section_headers; // 1st ARM11?, 3rd ARM9
+    std::array<u8, 0x100> signature; // RSA-2048 signature of the FIRM header's hash
+};
+
+struct ARM9_HEADER {
+    AESKey enc_key_x;
+    AESKey key_y;
+    AESKey CTR;
+    std::array<u8, 8> size;  // in ASCII
+    INSERT_PADDING_BYTES(8); // Unknown
+    std::array<u8, 16> control_block;
+    std::array<u8, 16> hardware_debug_info;
+    std::array<u8, 16> enc_key_x_slot_16;
+};
 
 std::string KeyToString(AESKey& key) {
     std::string s;
@@ -170,8 +206,11 @@ void LoadBootromKeys() {
 void LoadNativeFirmKeysOld3DS() {
     // Use the save mode native firm instead of the normal mode since there are only 2 version of it
     // and thus we can use fixed offsets
+
     constexpr u64_le save_mode_native_firm_id_low = 0x0004013800000003;
 
+    // TODO(B3N30): Add the 0x25 KeyX that gets initalized by native_firm
+
     FileSys::NCCHArchive archive(save_mode_native_firm_id_low, Service::FS::MediaType::NAND);
     std::array<char, 8> exefs_filepath = {'.', 'f', 'i', 'r', 'm', 0, 0, 0};
     FileSys::Path file_path = FileSys::MakeNCCHFilePath(
@@ -213,6 +252,125 @@ void LoadNativeFirmKeysOld3DS() {
     }
 }
 
+void LoadNativeFirmKeysNew3DS() {
+    // The first 0x10 bytes of the secret_sector are used as a key to decrypt a KeyX from the
+    // native_firm
+    const std::string filepath =
+        FileUtil::GetUserPath(FileUtil::UserPath::SysDataDir) + SECRET_SECTOR;
+    auto secret = FileUtil::IOFile(filepath, "rb");
+    if (!secret) {
+        return;
+    }
+    ASSERT(secret.GetSize() > 0x10);
+
+    AESKey secret_key;
+    secret.ReadArray(secret_key.data(), secret_key.size());
+
+    // Use the save mode native firm instead of the normal mode since there are only 1 version of it
+    // and thus we can use fixed offsets
+    constexpr u64_le save_mode_native_firm_id_low = 0x0004013820000003;
+
+    // TODO(B3N30): Add the 0x25 KeyX that gets initalized by native_firm
+
+    // TODO(B3N30): Add the 0x18 - 0x1F KeyX that gets initalized by native_firm. This probably
+    // requires the normal native firm with version > 9.6.0-X
+
+    FileSys::NCCHArchive archive(save_mode_native_firm_id_low, Service::FS::MediaType::NAND);
+    std::array<char, 8> exefs_filepath = {'.', 'f', 'i', 'r', 'm', 0, 0, 0};
+    FileSys::Path file_path = FileSys::MakeNCCHFilePath(
+        FileSys::NCCHFileOpenType::NCCHData, 0, FileSys::NCCHFilePathType::ExeFS, exefs_filepath);
+    FileSys::Mode open_mode = {};
+    open_mode.read_flag.Assign(1);
+    auto file_result = archive.OpenFile(file_path, open_mode);
+    if (file_result.Failed())
+        return;
+
+    auto firm = std::move(file_result).Unwrap();
+    std::vector<u8> firm_buffer(firm->GetSize());
+    firm->Read(0, firm_buffer.size(), firm_buffer.data());
+    firm->Close();
+
+    FIRM_Header header;
+    std::memcpy(&header, firm_buffer.data(), sizeof(header));
+
+    auto MakeMagic = [](char a, char b, char c, char d) -> u32 {
+        return a | b << 8 | c << 16 | d << 24;
+    };
+    if (MakeMagic('F', 'I', 'R', 'M') != header.magic) {
+        LOG_ERROR(HW_AES, "N3DS SAVE MODE Native Firm has wrong header {}", header.magic);
+        return;
+    }
+
+    u32 arm9_offset(0);
+    u32 arm9_size(0);
+    for (auto section_header : header.section_headers) {
+        if (section_header.firmware_type == FirmwareType::ARM9) {
+            arm9_offset = section_header.offset;
+            arm9_size = section_header.size;
+            break;
+        }
+    }
+
+    if (arm9_offset != 0x66800) {
+        LOG_ERROR(HW_AES, "ARM9 binary at wrong offset: {}", arm9_offset);
+        return;
+    }
+    if (arm9_size != 0x8BA00) {
+        LOG_ERROR(HW_AES, "ARM9 binary has wrong size: {}", arm9_size);
+        return;
+    }
+
+    ARM9_HEADER arm9_header;
+    std::memcpy(&arm9_header, firm_buffer.data() + arm9_offset, sizeof(arm9_header));
+
+    AESKey keyX_slot0x15;
+    CryptoPP::ECB_Mode<CryptoPP::AES>::Decryption d;
+    d.SetKey(secret_key.data(), secret_key.size());
+    d.ProcessData(keyX_slot0x15.data(), arm9_header.enc_key_x.data(), arm9_header.enc_key_x.size());
+
+    key_slots.at(0x15).SetKeyX(keyX_slot0x15);
+    key_slots.at(0x15).SetKeyY(arm9_header.key_y);
+    auto normal_key_slot0x15 = key_slots.at(0x15).normal;
+    if (!normal_key_slot0x15) {
+        LOG_ERROR(HW_AES, "Failed to get normal key for slot id 0x15");
+        return;
+    }
+
+    constexpr u32 ARM9_BINARY_OFFSET = 0x800; // From the beginning of the ARM9 section
+    std::vector<u8> enc_arm9_binary;
+    enc_arm9_binary.resize(arm9_size - ARM9_BINARY_OFFSET);
+    ASSERT(enc_arm9_binary.size() + arm9_offset + ARM9_BINARY_OFFSET < firm_buffer.size());
+    std::memcpy(enc_arm9_binary.data(), firm_buffer.data() + arm9_offset + ARM9_BINARY_OFFSET,
+                enc_arm9_binary.size());
+
+    std::vector<u8> arm9_binary;
+    arm9_binary.resize(enc_arm9_binary.size());
+    CryptoPP::CTR_Mode<CryptoPP::AES>::Decryption d2;
+    d2.SetKeyWithIV(normal_key_slot0x15->data(), normal_key_slot0x15->size(),
+                    arm9_header.CTR.data(), arm9_header.CTR.size());
+    d2.ProcessData(arm9_binary.data(), enc_arm9_binary.data(), enc_arm9_binary.size());
+
+    AESKey key;
+    constexpr std::size_t SLOT_0x31_KEY_Y_OFFSET = 517368;
+    std::memcpy(key.data(), arm9_binary.data() + SLOT_0x31_KEY_Y_OFFSET, sizeof(key));
+    key_slots.at(0x31).SetKeyY(key);
+    LOG_DEBUG(HW_AES, "Loaded Slot0x31 KeyY: {}", KeyToString(key));
+
+    auto LoadCommonKey = [&arm9_binary](std::size_t key_slot) -> AESKey {
+        constexpr std::size_t START_OFFSET = 541065;
+        constexpr std::size_t OFFSET = 0x14; // 0x10 bytes for key + 4 bytes between keys
+        AESKey key;
+        std::memcpy(key.data(), arm9_binary.data() + START_OFFSET + OFFSET * key_slot, sizeof(key));
+        return key;
+    };
+
+    for (std::size_t key_slot{0}; key_slot < 6; ++key_slot) {
+        AESKey key = LoadCommonKey(key_slot);
+        common_key_y_slots[key_slot] = key;
+        LOG_DEBUG(HW_AES, "Loaded common key{}: {}", key_slot, KeyToString(key));
+    }
+}
+
 void LoadPresetKeys() {
     const std::string filepath = FileUtil::GetUserPath(FileUtil::UserPath::SysDataDir) + AES_KEYS;
     FileUtil::CreateFullPath(filepath); // Create path if not already created
@@ -288,7 +446,7 @@ void InitKeys() {
         return;
     LoadBootromKeys();
     LoadNativeFirmKeysOld3DS();
-    // TODO(B3N30): Load new_3ds save_native_firm
+    LoadNativeFirmKeysNew3DS();
     LoadPresetKeys();
     initialized = true;
 }