[Linux] Read AirPods state from BLE broadcast when not connected (#138)

* Fix possible build error

* [Linux] Read AirPods state from BLE broadcast when not connected

* SImplify

* Remove old code

* Remove old code

* Maintain charging state when state is unknown

* Simplify

* Remove unused var

linux/ble/bleutils.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include <QObject>
+#include <QByteArray>
+
+class BLEUtils : public QObject
+{
+    Q_OBJECT
+public:
+    explicit BLEUtils(QObject *parent = nullptr);
+
+    /**
+     * @brief Verifies if the provided Bluetooth address is an RPA that matches the given Identity Resolving Key (IRK)
+     * @param address The Bluetooth address to verify
+     * @param irk The Identity Resolving Key to use for verification
+     * @return true if the address is verified as an RPA matching the IRK
+     */
+    static bool verifyRPA(const QString &address, const QByteArray &irk);
+
+    /**
+     * @brief Checks if the given IRK and RPA are valid
+     * @param irk The Identity Resolving Key
+     * @param rpa The Resolvable Private Address
+     * @return true if the RPA is valid for the given IRK
+     */
+    Q_INVOKABLE static bool isValidIrkRpa(const QByteArray &irk, const QString &rpa);
+
+    /**
+     * @brief Decrypts the last 16 bytes of the input data using the provided key with AES-128 ECB
+     * @param data The input data containing at least 16 bytes
+     * @param key The 16-byte key for decryption
+     * @return The decrypted 16 bytes, or an empty QByteArray on failure
+     */
+    static QByteArray decryptLastBytes(const QByteArray &data, const QByteArray &key);
+
+private:
+    /**
+     * @brief Performs E function (AES-128) as specified in Bluetooth Core Specification
+     * @param key The key for encryption
+     * @param data The data to encrypt
+     * @return The encrypted data
+     */
+    static QByteArray e(const QByteArray &key, const QByteArray &data);
+
+    /**
+     * @brief Performs the ah function as specified in Bluetooth Core Specification
+     * @param k The IRK key
+     * @param r The random part of the address
+     * @return The hash part of the address
+     */
+    static QByteArray ah(const QByteArray &k, const QByteArray &r);
+};