18.9. Transport Layer Security (TLS and DTLS)

So far we have discussed security protocols at layers 2 and 3. The most widely used protocol for security operates just above the transport layer and is called Transport Layer Security (TLS). TLS is used for securing Web communications and for several other popular protocols, including POP and IMAP (which are called POP3S and IMAPS, respectively, when protected with TLS). One reason for TLS’s popularity is that it can be implemented within or underneath applications that ride on top of the lower layers, whereas protocols such as EAP and IPsec usually require capabilities within the operating systems and protocol implementations of hosts and embedded devices.

There are several versions of TLS and its ...

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