Re: [TLS] make ChangeCipherSpec a handshake message

[Ilari Liusvaara <[e-mail]>]

On Sun, Dec 28, 2014 at 06:06:39PM +0100, Hauke Mehrtens wrote:
> Why is ChangeCipherSpec a special type and not just a handshake message?
> It is only send in the handshake and preceded and followed by handshake
> messages.
> 
> DTLS has some functionality for reordering of handshake messages. All
> the handshake messages have a message_seq field which is used to bring
> the messages into the right order again and detect duplicates. The
> messages can get into the wrong order if they are send independently and
> not the hole flight in one turn. This gets even messier when the
> packages are getting retransmitted. When packages are getting
> retransmitted all packages from a flight are getting retransmitted even
> if just one of these packages were not received. With the message_seq
> field one can detect if this package was already received and what is
> the next package to handle.

I think the plan is to rip out CCS entierely, that is, rely on handshake
state machine to initate the key transitions (which should make it more
difficult to get wrong).


-Ilari