According to Cook, the government's objective would require Apple to create a backdoor into its devices which currently doesn't exist, leaving thousands at risk.
"The government suggests this tool could only be used once, on one phone," he said. "But that's simply not true.
"Once created, the technique could be used over and over again, on any number of devices. In the physical world, it would be the equivalent of a master key, capable of opening hundreds of millions of locks — from restaurants and banks to stores and homes. No reasonable person would find that acceptable."
The company will have five days to file an appeal of the federal court's order.