Sprinkle entire surface of chicken with salt, with an emphasis on legs and breasts. Place in a baking dish, cover with plastic wrap and refrigerate for 2 days.
With the rack in the middle position, preheat the oven to 190° C (375 °F).
In a bowl, combine ketchup and butter. Gently lift skin from breasts and thighs, without tearing. Spread butter mixture between meat and skin.
In another bowl, combine all spices. Sprinkle spice mixture over entire surface of chicken. Place back in the baking dish (see note). Roast for about 1 hour and 15 minutes or until a thermometer inserted in the thigh without touching bone reads 82 °C (180 °F). Baste with pan juices halfway through cooking. Keep chicken warm.
When roasting a whole chicken, use a fairly large baking dish because, if it is too small, there will be an accumulation of cooking juices and chicken won’t roast very well.