Define secure. Because if you were trying to bring up a technological argument, please stop. It weakens our position. Cryptographically you absolutely can have asymmetric systems with a privileged master key that are secure to anyone not knowing the master key. You might argue that the key could leak, and they'll come right back with ephemerally rotating master keys signed by the backdoor agency. Legally enforced secure backdooring is not a technology issue, it is a social one.

Simply put, we don't want mass surveillance. We don't want authorities snooping in our private communications, period. That is more than sufficient, and does not require building on technological arguments that will only wear down.