What is DTLS or Datagram Transport Layer Security?

Otherwise known as Secure Real-time Transport Protocol, DTLS (Datagram Transport Layer Security) is used where low latency or "delay sensitive" data must be secured, such as Voice over IP, VPN, Video Conferencing, and various real-time and Massively Multiplayer Online Games.

Much as TLS (Transport Layer Security), a derivative of SSL  (Secure Socket Layer), is used to protect Internet traffic such as HTTPS, FTPS, and IMAPS from eavesdropping, DTLS provides the same reassurance that your delay sensitive streaming data is secured.


Most of today's client software for these protocols, such as Cisco's Anyconnect VPN client,  have DTLS already implemented.

DTLS is also used to secure the transmission control channels for various streaming protocols, such as Datagram Congestion Control Protocol (DCCP), Stream Control Transmission Protocol (SCTP), and Secure Real-time Transport Protocol (SRTP)

(Another great article I found on the difference between SSL, TLS, and STARTTLS)

References:

The Design and Implementation of Datagram TLS
Wikipedia: Datagram Transport Layer Security
Wikipedia: Secure Real-time Transport Protocol
IETF: Suite B Profile for Datagram Transport Layer Security / Secure Real-time Transport Protocol
Wikipedia: Comparison of TLS implementations
IETF: RFC 6347 for  User Datagram Protocol (UDP)
IETF: RFC 5238 for  Datagram Congestion Control Protocol (DCCP),
IETF: RFC 6083 for  Stream Control Transmission Protocol (SCTP) encapsulation,
IETF: RFC 5764 for  Secure Real-time Transport Protocol (SRTP)