Military Communications and Information Technology: A Trusted ...
Military Communications and Information Technology: A Trusted ... Military Communications and Information Technology: A Trusted ...
478 Military Communications and Information Technology... weeks depending on number of couriers, number of served devices and devices network topology. In the case of the electronic distribution, secure communication infrastructure used to transfer of the data is available. So the time of the distribution can be treat as negligible in this case. The graphs presented in Fig. 2 show the example of timing dependencies of the whole process of the data preparation in case of courier (1) and electronic distribution (2). The mutual proportions of the time of planning and time of generation can be different depending on the applied method of the planning. However in the first case their total time will certainly be much smaller than the time of courier distribution. The efficiency of planning and generation have no bigger meaning, because the distribution is the bottleneck. In second case, the whole process of the data preparation become significantly shorter. In this situation new profitable possibilities appear (presented in Fig. 3): giving more time for analysis process and shortening the validity period. The second solution increases security for data protection system. In both solutions the planning is more effective because the needs for cryptographic relations known at the beginning of planning are more adequate to real needs existing in the moment of introducing the keys to use. In this case the planning and generation become bottleneck. It is necessary to determine if optimization of planning time and generation time is possible. Let’s begin from generation process. The total time of generation is equal to the product of generation time of single key and number of required keys. The time of generation of single key follows from the property of random generator and, for concrete solutions, is a fixed value. Let’s assume that generation of one key lasts 1 second. Figure 1. Life cycle of cryptographic data Figure 2. Timing dependencies in process of data preparation
Chapter 4: Information Assurance & Cyber Defence 479 Figure 3. Timing dependencies in case of electronic distribution The number of keys is equal to the number of cryptographic relations established in planning process. The number of relations depends not only on real needs but also on applied method of planning: “each to each” or “according to needs”. IV. Each to each method In the method each to each all possible cryptographic relations are set, which means that each device can communicate with any other in secret mode. Assume that R is the number of relations and the N – the number of users. Then: R = ½ * N * (N-1). In this case, the planning process is reduced to producing the order for the cryptographic data. Basing on the order, the generation subsystem will produce the required keys. The table 1 gives the total generation time for different numbers of devices (assuming that the generation of a single key takes 1 second). Advantages: The planning process is very easy to implement and its execution time is negligibly short. Disadvantages: Generation of a large number of keys (many of them will probably never be used). Too long generation time, in some cases unacceptable. V. Pareto principle The alternative for “each to each” method is “according to needs” method. However, can we expect significant shorte-ning of generation time, when a concrete system and its needs in range of cryptographic relations are unknown At the beginning we can refer to our own life experiences. Probably each user of mail or mobile phone can find in his address book a few such contacts which added long time ago and were never used after. From second side the same user could mention a few such contacts which are used definitely more often then the others. As confirmation of this what follows from experiences it is worth to quote the conclusions of Italian economist Pareto. Vilfredo Pareto observed in 1906 that 80% of the land in Italy was owned by 20% of the population. This rule called Pareto principle (also known as rule 80-20), has many expressions concerning
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Chapter 4: <strong>Information</strong> Assurance & Cyber Defence<br />
479<br />
Figure 3. Timing dependencies in case of electronic distribution<br />
The number of keys is equal to the number of cryptographic relations established<br />
in planning process. The number of relations depends not only on real needs<br />
but also on applied method of planning: “each to each” or “according to needs”.<br />
IV. Each to each method<br />
In the method each to each all possible cryptographic relations are set, which<br />
means that each device can communicate with any other in secret mode. Assume<br />
that R is the number of relations <strong>and</strong> the N – the number of users. Then:<br />
R = ½ * N * (N-1).<br />
In this case, the planning process is reduced to producing the order for<br />
the cryptographic data. Basing on the order, the generation subsystem will produce<br />
the required keys. The table 1 gives the total generation time for different numbers<br />
of devices (assuming that the generation of a single key takes 1 second).<br />
Advantages: The planning process is very easy to implement <strong>and</strong> its execution<br />
time is negligibly short.<br />
Disadvantages: Generation of a large number of keys (many of them will<br />
probably never be used). Too long generation time, in some cases unacceptable.<br />
V. Pareto principle<br />
The alternative for “each to each” method is “according to needs” method.<br />
However, can we expect significant shorte-ning of generation time, when a concrete<br />
system <strong>and</strong> its needs in range of cryptographic relations are unknown<br />
At the beginning we can refer to our own life experiences. Probably each<br />
user of mail or mobile phone can find in his address book a few such contacts<br />
which added long time ago <strong>and</strong> were never used after. From second side the same<br />
user could mention a few such contacts which are used definitely more often then<br />
the others. As confirmation of this what follows from experiences it is worth to<br />
quote the conclusions of Italian economist Pareto. Vilfredo Pareto observed in 1906<br />
that 80% of the l<strong>and</strong> in Italy was owned by 20% of the population. This rule called<br />
Pareto principle (also known as rule 80-20), has many expressions concerning
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