Iot sdk thesis

2.5
 
Datagram Transport Layer Security (DTLS) 
Technological advancements in last couple of decades have elicited the emergence of 
many applications that do not require reliable, in-order transport of packets. That is because, 
these applications prefer low latency over reliable delivery of all packets. Such applications 
include VoIP, internet telephony, video-conferencing, streaming etc.
In IoT, many applications and usecases necessitate very optimum usage of available 
resources: power, hardware, bandwidth. Typical TCP-based protocols like HTTP prove to be 
unsuitable while keeping the power, hardware and bandwidth usage minimal. Sometimes, it is 
not even feasible. Hence, many IoT usecases implement UDP-based protocols like CoAP which 
have been specifically designed with resource constraints in mind. So, the usability of UDP-
based communication which is connectionless, unreliable, out-of-order is growing every day.
Now, to keep the packet traffic secure from the attackers, a robust encryption suite has 
to be in place. Transport Layer Security (TLS) is a popular encryption protocol seen HTTP, 
IMAP (used for emails), POP. However, TLS can work only over reliable transfer protocol like 
TCP. Hence, TLS cannot be used to offer a secure UDP-based communication. To work around 
this issue, Datagram Transport Layer Protocol (DTLS) was conceived, which can offer TLS-
like security over unreliable protocols like UDP. In practical sense, DTLS is a modified TLS to 
compensate for unreliability of UDP-like protocols [24]. Thus, in order to understand DTLS, it 
is useful to understand TLS first. 
2.5.1
 
Transport Layer Security (TLS) 
TLS is an application layer security protocol that establishes a secure channel for 
communicating entities with following main security features: a) Authentication of the server; 
b) Confidentiality of the communication channel; c) Message integrity of the communication 
channel; d) Authentication of the client (Optional) [23] 
Protocol 
TLS is a layered protocol, where four types of payloads are carried in “records” over 
TCP. The layered architecture of TLS is shown in Figure 2.5.1.1:

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