Does protection from a color prevent the permanent from being targeted by colorless spells?

Protection from a color grants four specific shields, often remembered by the acronym DEBT: the permanent cannot be Damaged, Enchanted/Equipped/Fortified, Blocked, or Targeted by anything of that color (CR 702.16b). A colorless spell or ability is exactly that — it has no color at all — so it does not match the protected color and none of the four shields apply.

Color is a property defined by a card's color indicator or the colors of mana in its mana cost (CR 105.2). A spell with a generic or colorless mana cost (such as {3} or {C}) has no color. Because the protection definition requires the source to be the protected color, a colorless source simply fails that test.

This means a creature with protection from blue can still be targeted by a colorless spell like Warping Wail or affected by a colorless artifact's activated ability. The protection offers zero defense against colorless sources.

Concrete example: Your opponent controls a Paladin en-Vec (protection from black and red). You cast Spatial Contortion ({1}{C}), which is colorless. Paladin en-Vec has no protection from colorless, so it is a legal target and will take the -3/-3 effect normally.

If you want to protect a permanent from colorless spells and abilities, you would need a different form of protection — such as "protection from colorless" granted by cards like Eldrazi Conscription or certain Zendikar Rising cards — which explicitly names colorless as the protected quality (CR 702.16b).