Place all the chicken brine ingredients in a pot and bring to a boil.
Boil the brine for 1 minute, until the salt dissolves, then chill it completely. If you’re in a hurry, you can place the mixture in a bowl and set that in an ice bath. Otherwise, let it chill to room temperature, then place it in the fridge.
Once the mixture is chilled, place the chicken in the brine for 8 hours. Try not to go beyond 8 hours or the chicken will get too salty.
Discard the brine and pat the chicken very dry with paper towels. Let the chicken sit at room temperature for 1 hour while you prep the other ingredients.
Mix the flour with the garlic powder, onion powder, paprika, cayenne, salt, and pepper. Split this between two bowls. Place the buttermilk in a third bowl, set in between the two spiced flour bowls.
Preheat a deep fryer to 320 degrees F, and right before frying, dip the drumsticks and thighs into the flour mixture, then the buttermilk, then the flour mixture again.
Fry the drumsticks and thighs for 10 minutes, until golden brown and 170 degrees F inside, then drain on paper towels.
Raise the fryer heat to 340 degrees F, and dip the wings and breasts into the flour, then the buttermilk, then the flour again.
Fry the wings and breasts for 6 to 7 minutes, until golden brown and cooked to 160 degrees F, then drain on paper towels.