What is DTLS and how is it used?
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原文地址：https://hackcontrol.org/blog/what-is-dtls-and-how-is-it-used/
DTLS is used for internet telephony, streaming, gaming and VPNs, among other things. The Datagram Transport Layer Security protocol builds on the secure TLS, with the great advantage that packets cannot be lost and they always arrive in the correct order. But what exactly is DTLS? And what are its benefits?
SSL, TLS and DTLS are three protocols that use certificate-based authentication in combination with symmetric encryption to secure data sent over an untrusted network. DTLS, which stands for Datagram Transport Layer Security, is based on the Transport Layer Security (TLS) protocol and built on top of the User Datagram Protocol (UDP).
WHAT EXACTLY IS DTLS?
DTLS protects the transport of datagrams. When designing the protocol, security experts adhered to TLS as much as was possible. As a result, the number of new security techniques needed could be kept to a minimum, while preserving the code and infrastructure as much as possible.
Therefore, DTLS offers as many security guarantees as TLS but reduces the need to use IPsec or design a custom application layer security protocol. The main difference between DTLS and TLS is that DTLS is built on UDP, while TLS uses Transmission Control Protocol (TCP).
DATAGRAMS, UDP AND DTLS
A datagram is a kind of telegram with digital data: as a data packet, it contains sufficient information to find its own route to the correct destination without a prior connection between the sender and the receiver. This makes the connection unreliable: the sender cannot determine whether his message has been received, while the recipient does not know whether the packets have arrived in the correct order.
The User Datagram Protocol – using which messages can be sent without a connection – is mainly used when fast data transfer and short response times are more important than reliability. Consider, for example, situations in which data may be lost because new data immediately follows and replaces old data, such as in video streaming or gaming. DTLS is designed in such a way that packages do not get lost or arrive in the wrong order.
THE BENEFITS OF DTLS
DTLS is a secure protocol, as it provides privacy with datagram protocols. As a result, communication between client-server applications is possible without the communication being overheard or manipulated.
DTLS also solves the problems surrounding the loss and reordering of packets, while it does not suffer from delays that occur with streaming protocols.
WHAT IS DTLS USED FOR?
DTLS is particularly suitable for securing applications and services that use datagram transport because they are sensitive to delays. Think of real-time applications such as internet telephony, online gaming and streaming video and audio. Developers can also use the DTLS protocol to secure communications between clients and servers.
Finally, DTLS can improve the performance of a VPN. The speed of a Virtual Private Network can drop when a TCP connection is used within another TCP connection. Since most internet traffic is still TCP-based, it is better to set up a UDP-based tunnel. The speed of the VPN can therefore improve enormously.