| Abstract [eng] |
Nowadays technologies are being improved rapidly – extremely fast dedicated servers, high internet and network throughput, enables more and more applications to be moved to a virtual space, which is called ‘Cloud computing’. Cloud computing is responsible that all shared computer resources, like Software, Hardware and Network would be allocated for services in optimal way. This feature enables to appear new services, like media streaming, documents editing online etc. This kind of services are based on ‘Thin client’ architecture, which is especially important for mobile devices. Main feature of this architecture is that applications which require many computations, now can be executed in dedicated servers and results can be displayed in mobile device screen. Fact, that aplication is not executed in mobile device environment decreases probability that important information will be infected by viruses, worms etc. However, between many existing problems with mobile devices there are two major which should be stated in the first place: energy consumption and information security. The first issue is due to inadequate progress of computational resources and battery energy power (e.g., CPU speed, memory capacity is being increased several times within a few years, while battery power doubles only in a decade). The second issue is closely related with the first one. Today people want to work anywhere, so there is abillity that mobile devices including important information could be stolen or lost. That‘s why in order to protect data from publishing it in readable form we must encrypt it. To better understand the relation between strength of the crypto algorithm and battery energy consumption we have chosen to investigate Rijndael symmetric encryption algorithm. This algorithm because of different key lengths (longer key means better strength) and block sizes is universal and used widely including mobile devices. Solutions of .NET Compact Framework platform have motivated us to programme a tool which has calculated the energy consumption of encryption and decryption processes which were based on Rijndael algorithm. The results of research have shown that „Pareto optimal“ values, which show the best ratio between strength of the Rijndael crypto algorithm and battery energy consumption, are achieved when key lengths and block sizes are equal. Moreover, based on the experiment results, we can construct three security profiles for mobile device users as follows: 1) low energy / low security – so far considered secure, but theoretically crackable; 2) medium energy / medium security – suitable for very secret information, consumes ~10% more energy than low energy/security profile; 3) high energy / high security – suitable for top secret information, consumes ~12% more energy than medium energy/security profile. |
