深信服VPN hardid研究

public String m() {
    String deviceId = this.i.checkPermission("android.permission.READ_PHONE_STATE", Process.myPid(), Process.myUid()) == 0 ? ((TelephonyManager) this.i.getApplicationContext().getSystemService("phone")).getDeviceId() : null;
    if (deviceId == null) {
        deviceId = Build.VERSION.SDK_INT >= 29 ? u.g().d() : ((WifiManager) this.i.getApplicationContext().getSystemService("wifi")).getConnectionInfo().getMacAddress();
    }
    if (deviceId == null) {
        Log.a(h, "Can't get device's hardware Information.");
        return null;
    }
    try {
        byte[] digest = MessageDigest.getInstance("MD5").digest(deviceId.getBytes());
        StringBuilder sb = new StringBuilder(32);
        int length = digest.length;
        for (int i = 0; i < length; i++) {
            sb.append(String.format("%02X", Byte.valueOf(digest[i])));
        }
        return sb.toString();
    } catch (NoSuchAlgorithmException e) {
        Log.a(h, "Can't generate device's hardware ID.", e);
        return null;
    }
}