Subject: RE: [TLS] Record layer corner cases

From: Peter Williams <[email-masked]>
Date: Sun, 17 Dec 2006 10:34:08 -0800

I'm getting confused.
 
its one thing to worry about whether a record-layer record straddles one or more packets - given the legitimate issues that timing factors always have on all Security Protocol designs.
 
Its another to say a given handshake message can *always* straddle multiple records. This depends on the protocol version, as a part of TLS fallback rules.
 
-----------------
 
The latter was specifically made NON CONFORMING (in SSL2 ).  "For a two byte header, the maximum record length is 32767 bytes. For the three byte header, the maximum record length is 16383 bytes. The SSL Handshake Protocol messages are constrained to fit in a single SSL Record Protocol record. Application protocol messages are allowed to consume multiple SSL Record Protocol record's."
 
In SSL3, of course, the priority of transferring a given record type is a function of the upper-layer protocols. There is no equivalent rule in SSL3 to SSL2. One may decide to interrupt flow of a 32k cert chain on the client auth portion of a second handshake say (initiated by whoever holds the client role - due to a 30s timeout of its session policy - because of the need to prioritize transfer of some APDU (e.g. SSL protected APDU over some TLS extension, over OOB media). Obviously, One continues the back half of the certchain conveyance after the APDU has been signalled, and the client protocol machine can expect the server to properly handle such fragmentation of a handshake message.
 
> > o Do you correctly handle handshake messages that are fragmented> > to multiple TLS records? Also corner cases like a ClientHello> > that is split to several small fragments?
> Yes, this looks very good!> > Bodo
_________________________________________________________________
All-in-one security and maintenance for your PC.  Get a free 90-day trial!
http://www.windowsonecare.com/purchase/trial.aspx?sc_cid=wl_wlmail

_______________________________________________
TLS mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/tls