Information Technology Reference
remote controls for TV, stereo, DVD, VCR, curtains, central heating and air-
conditioning through our houses. Instead, it would be interesting if all these
systems obey to a one single universal remote control, which typically is
generally a personal digital assistant (PDA) or something similar.
It won't be necessary to buy a remote with the device, you only need to
establish an association between your PDA and the new device. Since you do
not want your neighbour is able to activate your own devices, this association
must be secure.
However this association could also be revoked (we must be able to sell
our old stereo retaining our PDA and replace a broken PDA without losing
control of all our devices), for this reason the Resurrecting Duckling 
policy has been developed.
To secure wireless communications, protocols have been developed with the
aim to guarantee a certain level of security for data transmitted and to give a
control access to systems connected to a network.
A protocol is a set of rules that governs sequence and exchange of
messages, or control signals, and the connection between devices.
There are different types of protocols that operate at different levels of the
ISO/OSI stack, from the lowest to relate the simple management of electrical
signals for communication to the highest such as security and authentication
 that are going to analyse in greater depth.
2.1 Guarantees of a security protocol
A security protocol is a sequence of message exchanges between agents on
an unsafe mean. Security protocols are usually executed before the communi-
cation protocols. However, this is not a rule.
According to the ISO standard, the main requirements that a secure net-
work must satisfy  are: confidentiality , integrity and non-repudiatebility .
Confidentiality of data : data sent and received should not be accessible to
Confidentiality of the traffic flow : prevents the acquisition of information
from observation of the characteristics of data traffic and
Confidentiality of place : ensures the confidentiality of the location of