[Cryptography] SSL combines two aspects of communication
andreas.junius at gmail.com
Tue Jan 13 18:30:50 EST 2015
I've been working on a secure application for a while that is based on
https. One of the problems I found with SSL is that it combines two
aspects of communication, i.e. authentication and encryption. These two
aspects have contradicting requirements. One of the requirements for
authentication is that the certificate should not frequently change
(most SSL certificates are valid for one or two years). And I think an
important requirement for encryption is that a key gets not longer used
than absolutely necessary, i.e. it should be as short-living as possible.
So what I did was adding an additional level for encryption underneath
SSL (all at application level for a start). My server has two
certificates now; the SSL certificate for authentication and another one
that serves as the servers own CA. The server uses this CA certificate
to sign what I call an “encryption certificate”, that it delivers to the
client. This “encryption certificate” gets generated by the application
server on a regular basis. The interval can be set via parameter,
depending on the security needs of the application, e.g. re-generate
after 4 weeks or 2 weeks or even on every request/session.
I did all this because some sources claim the NSA is able to crack a SSL
key in about 10 days; which means they can then read all communication
with the targeted server for the remaining validity period of the SSL
certificate. If the key changes on a regular basis, their job will be
But the question remains: does this system actually add to security?
What do you think?
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