feat: crypto: Add basic AES keyslot manager

We loads keys from AppData/Alber/sysdata/aes_keys.txt.

NOTE: We do differ from other emulators by not hardcoding the generator key, it's the user responsibility to provide it in aes_keys.txt.

src/core/crypto/aes_engine.cpp

@@ -0,0 +1,84 @@
+#include <iostream>
+#include <fstream>
+
+#include "crypto/aes_engine.hpp"
+#include "helpers.hpp"
+
+namespace Crypto {
+	void AESEngine::loadKeys(const std::filesystem::path& path) {
+		std::ifstream file(path, std::ios::in);
+	
+		if (file.fail()) {
+			Helpers::warn("keys: Couldn't read key file: %s", path.c_str());
+			return;
+		}
+
+		while (!file.eof()) {
+			std::string line;
+
+			std::getline(file, line);
+
+			// Skip obvious invalid lines
+			if (line.empty() || line.starts_with("#")) {
+				continue;
+			}
+
+			const auto parts = Helpers::split(line, '=');
+
+			if (parts.size() != 2) {
+				Helpers::warn("keys: Failed to parse %s", line.c_str());
+				continue;
+			}
+
+			const std::string& name = parts[0];
+			const std::string& rawKeyHex = parts[1];
+
+			std::size_t slotId;
+			char keyType;
+
+			bool is_generator = name == "generator";
+
+			if (!is_generator && std::sscanf(name.c_str(), "slot0x%zXKey%c", &slotId, &keyType) != 2) {
+				Helpers::warn("keys: Ignoring unknown key %s", name.c_str());
+				continue;
+			}
+
+			auto key = createKeyFromHex(rawKeyHex);
+
+			if (!key.has_value()) {
+				Helpers::warn("keys: Failed to parse raw key %s", rawKeyHex.c_str());
+				continue;
+			}
+
+			if (is_generator) {
+				m_generator = key;
+				continue;
+			}
+
+			if (slotId >= AesKeySlotCount) {
+				Helpers::warn("keys: Invalid key slot id %u", slotId);
+				continue;
+			}
+
+			switch (keyType) {
+				case 'X':
+					setKeyX(slotId, key.value());
+					break;
+				case 'Y':
+					setKeyY(slotId, key.value());
+					break;
+				case 'N':
+					setNormalKey(slotId, key.value());
+					break;
+				default:
+					Helpers::warn("keys: Invalid key type %c", keyType);
+					break;
+			}
+		}
+
+		// As the generator key can be set at any time, force update all normal keys.
+		for (std::size_t i = 0; i < AesKeySlotCount; i++) {
+			updateNormalKey(i);
+		}
+	}
+};

src/emulator.cpp

@@ -135,8 +135,15 @@ bool Emulator::loadROM(const std::filesystem::path& path) {
     // Inside that path, we be use a game-specific folder as well. Eg if we were loading a ROM called PenguinDemo.3ds, the savedata would be in
     // %APPDATA%/Alber/PenguinDemo/SaveData on Windows, and so on. We do this because games save data in their own filesystem on the cart
     char* appData = SDL_GetPrefPath(nullptr, "Alber");
-    const std::filesystem::path dataPath = std::filesystem::path(appData) / path.filename().stem();
+    const std::filesystem::path appDataPath = std::filesystem::path(appData);
+    const std::filesystem::path dataPath = appDataPath / path.filename().stem();
+    const std::filesystem::path aesKeysPath = appDataPath / "sysdata" / "aes_keys.txt";
     IOFile::setAppDataDir(dataPath);
+
+    if (std::filesystem::exists(aesKeysPath)) {
+        aesEngine.loadKeys(aesKeysPath);
+    }
+
     SDL_free(appData);
 
     kernel.initializeFS();