I don't get why everybody talks about Verisign or others giving them "keys". The NSA just need certificates for their own key, right? The only private key that

I don't get why everybody talks about Verisign or others giving them "keys". The NSA just need certificates for their own key, right? The only private key that Verisign could give them would be their signing key, which seems much too powerful and central for a signing authority to hand out.