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But one thing the NSA likes to say is that the backdoors they insert are only accessible to them, not to others.Which is an empty statement when it comes to security principles. If you've placed a backdoor (and some are blatantly obvious if you look for it, like some SSL issues), then others can use it too. Most backdoors are not of the "we have an encrypted password only we know" variety, but of the purposeful hole to exploit.
>I see the benefit of inserting multiple backdoors. But none of them should be vulnerable to rival nations.
Except if the idea is to monitor the local population, and you do not care that much if others monitor them too.