DTLS is in openssl 0.9.8a. There are some bugs in it and it doesn't exactly comply with the DTLS draft (the change cipherspec is incorrectly encoded). I am still waiting for patches to fix the problems. I didn't actually code anything with the openssl APIs. I only used the sample client/server apps for interop testing with a DTLS SDK I created for the company I work for. Take a look at the sample apps and you should be able to figure out most of the details for how to add it to your own app.

One thing to remember is that DTLS does not ensure that your application data is delivered reliably. Datagrams may be lost or arrive out of order. That is something you will have to deal with yourself. DTLS only ensures that the handshake protocol can be reliably negotiated, through a combination of message fragmentation and re-transmission timers. Alerts and application datagrams are never re-transmitted and may not be delivered in the same order they were sent by the peer. If you already have an application running over UDP then you probably already have a way for dealing with these issues or you maybe don't need to care. If you are moving an application from TCP w/TLS to UDP w/DTLS then you will have to implement some mechanism to handle these issues for your application data. I believe the openssl sample apps simply ignore these issues.

hope this helps

rob


From: Pjothi <[EMAIL PROTECTED]>
Reply-To: openssl-users@openssl.org
To: openssl-users@openssl.org
Subject: Does OpenSSL has DTLS support
Date: Sat, 28 Jan 2006 20:14:47 +0100

 Dear all,

Does OpenSSL has DTLS support ? If yes, from which version is DTLS supported
? Are there any tutorials /briefs avaiable for adding DTLS support for
applications?

It would be very helpful if any of you can give me some  information
regarding this,

I thank you one and all,

regards,
Pjothi


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