Why use DTLS over SCTP?

Question

Why use DTLS over SCTP when there is already TLS over SCTP ?

Is there any (good) reason or advantage for that idea?

I'm voting to close this question as off-topic because it is about [IT security](https://security.stackexchange.com) instead of programming. — Maarten Bodewes, Mar 25 '17 at 23:19
I disagree. Although Tim Panton mentions encryption in his answer, protocols also contain several features other than security. — user1511417, Mar 28 '17 at 12:57
Sorry, but this Q/A site is about programming / development questions. Could you point out how your question is on topic with this in mind? Do mind that I like the question, I am even responsible for the single upvote. But it's simply not about programming - that it has "features other than security" doesn't invalidate this. — Maarten Bodewes, Mar 28 '17 at 13:06
Let's simply say that I need to *develop* a (multimedia) application. You have to choose a specific protocol depending on what features are needed. For example: multi streaming, multihoming, packet ordering.. — user1511417, Mar 28 '17 at 13:32

score 6 · Accepted Answer · answered Mar 24 '17 at 08:30

TLS assumes an ordered delivery of cleartext messages. DTLS does not. SCTP supports both ordered and unordered delivery of messages.

So if you have an SCTP application that utilises unordered messages and needs an encryption layer then DTLS would be a good answer.

(Note however that WebRTC solves this the other way up, encapsulating the SCTP packets in DTLS and sending them over the wire.)

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