In a small bowl, stir together the mayonnaise and Sriracha. Cover with plastic wrap and chill until ready to serve.
Add the buttermilk to a bowl. Add the calamari, and let it soak; chill for at least 1 hour.
In a medium bowl, whisk together the flour, salt, pepper and paprika. Remove the calamari from the buttermilk and dredge it in the flour mixture. Shake off the excess, and separate the rings and tentacles.
Pour oil to depth of 2 inches into a large pot; heat to 365°F. Fry the calamari, in batches, 1 minute or until done. Drain on paper towels, and serve warm with the spicy mayonnaise.
Notes
Since it's impossible to know how much oil stays with the calamari after frying, the oil is not included in the nutritional information.