Your demand for independence is right. But since you are living under their roof, you need to abide by the house rules your parents have set. If they believe you should not return later than a specific time at night, give them valid reasons and inform them whenever you plan to come late.
If you are earning, contribute a part of it to the family expenses. Offer to help with the groceries or pay the electricity bill. Your presence should be a source of comfort to others. If your parents get the feeling that you are able to support yourself yet you are living with them, they will naturally let you a life without restrictions.
Help with the chores:
If you are unable to help with the finances, do it in the non monetary terms. Do the lawn on weekends, help with laundry and other chores around the house. The least you can do is not to be a burden by doing your own chores and not leaving them to family members. If you show responsibility people will automatically let you become independent.
Exhibit that you are mature enough:
If your parents realize that you are old and mature enough to decide for yourself and guard your interests, they will drop the protective parents mask. You have to prove in the first place that you can be relied upon through your character, activities and responsibilities. Do not bring in friends who mighty embarrass you in front of the family by doing crazy stuff. During a conflict with parents depend on logic and reason rather than your tone or fist. This will help in establishing a grown up air about you.
Maintain your space:
Keep your bedroom clean and prove that you can maintain it on your own. This will eliminate the reason for parents and siblings prying in to your room to clean or collect stuff. Inside the house respect the privacy of your parents and your siblings so that you get treated the same in return.