Comment Re:SMIME (Score 1) 243
Actually you are close but a little off. Verisign, Thawte, CAcert, Startcom, and the likes are trusted third parties, but they don't issue or generate your private key. You (via your browser software engine, smartcard, OpenSSL, etc.) generate your private key and send them your CSR (Certificate signing request) which contains your public key. The TTP then issues the certificate based on your public key and the CSR. The TTP never has your private key and therefore can't decrypt anything that was sent to you via your certificate, and can't sign anything to make it appear it came from your certificate.
The function of the TTP is for identification. Your browser is set to trust Verisign's signing key, so therefore when you visit https://supersecurewebsite.com/ your browser verifies that your certificate is signed by Verisign's, and therefore is trusted. Now you can use your own signing authority, as you called the "RSA key server" above, which is called self-signing your keys. You can still use it and it is just as cryptographically secure as using Verisign, however I don't know your signing authority from Sam, so my browser is going to warn me saying it is an untrusted signer. E-mail using such a certificate is the same, it will say the message is encrypted and has not been altered since it was sent, however the identify of the sender can not be confirmed. Now if I knew you personally and could meet with you to verify the fingerprint of your key, I could set my browser/e-mail client to trust your key (or your signer) and that warning would go away and be just as (really more so) secure than Verisign's signature.
When you get down to it, when you see the little lock icon on your browser, why do you trust it? Have you ever looked at the default list of trusted root keys? There are over 50 in my Firefox installation, and that is not including other authorities I've installed. AOL is not considered secure by anybody on the 'net, however their root key is installed as trusted by default in your browser. Why? Because at one point they talked their way onto the list way back in time, and while Mozilla now has a set list of requirements for new roots to be added, they have not gone back and applied those rules to roots already in place and basically grandfathered them in.
Even if the had its fingers inside of Verisign, Thawte, or any other root authority it doesn't make it any easier for them to decrypt your communications once it is been properly encrypted. At best it would let them generate a key for their own server, pretending to be https://supersecurewebsite.com/ and be a man in the middle.