Is it really "equivalent"? I get both problems are about entropy in the universe but I would have thought managing the state of a black is harder, due to its su

Is it really "equivalent"? I get both problems are about entropy in the universe but I would have thought managing the state of a black is harder, due to its suction into oblivion and whatnot. I don't know much about if it's possible to make entangled particles stable somehow, or whether you could maybe just have a lot of them so you never run out even if a lot become untangled naturally. Doesn't quantum key exchange use entangled particles? So it must be possible to keep them stable for at least a little while.