Kvantdatorer är en unik form av datorer som har fördelar över traditionella datorer i speciellaanvändningsområden. Ett av de områdena är den teoretiska möjligheten att knäcka deasymmetriska krypteringsmetoder som dagens kommunikation förlitar sig på. Arbetet inriktarsig på just RSA som idag är den vanligaste krypteringsmetoden. Säkerheten hos RSA ärbaserad på att faktoriseringsproblemet och svårigheten av att faktorisera stora tal vilket ärnågot traditionella datorer behöver hundratals år för att klara av. Kvantdatorer med sinenorma beräkningskapacitet kan potentiellt klara av samma primtalsfaktorisering under enbråkdel av tiden. Dagens kvantdatorer är inte tillräckligt utvecklade och saknarberäkningsförmågan för att vara ett hot, uträkningsförmågan beror på mängden kvantbitarsom är sammankopplade. Det största hindret kvantdatorer står inför är framsteg inomfeltolerans som ger möjligheten att bygga kvantdatorer med ett större antal kvantbitar som ärihopkopplade. När kvantdatorer når en punkt med tillräckligt många kvantbitar för att hotakryptering är en svår fråga att besvara men enligt studien bör det komma att ta många årinnan det kvantdatorer blir relevanta för det syftet. För att kunna göra en kvalificerad gissningpå när detta kommer inträffa kombineras flera experters syn av ämnet och en framtidsprognosbaserad på en regressionsanalys. Att nå möjligheten att knäcka RSA 2048 mellan år 2064 och2066 med 50 tusen kvantbitar anses vara någorlunda rimligt enligt den data och uträkningarsom utförts i arbetet.

This thesis deals with encryption of short text message (SMS) in mobile communication. Introduction is dedicated to overview of the parts of GSM radiotelephone nets and SMS messages transfer . Next chapter is reserved for description of cryptographic methods especially symetric and asymetric encryptografic aproaches. A design of a SMS messages encryption and decryption techniques is in next. For SMS encryption and sign, there is used the asymetric cypher RSA. Encryption use OAEP padding schema. The public key is saved in certificate. The Symbian OS has been choosen as a suitable platform for programming of mobile devices.

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Child pedestrian safety is one of the biggest safety issues regarding planning of a well arranged urban traffic. The fact that vulnerable road users suffer most from traffic incidents also raises concern for children. Children need special care while considering traffic safety. The factors are various that they differ from adults by many aspects. For their physically smaller size, immature ability to judge the traffic situations, lack of experience about traffic and mental deficiencies like losing concentration after short periods, they are much more susceptible to the traffic hazards than adults. Various studies have been carried and many applications regarding child and school pedestrian safety worldwide and the most hazardous periods were found as afternoon hours. Age factor generally is flexible but as the child grows older, mobility increases and risks become larger. The risk factors also include the social and economical environment that children living in good life standards suffer less than those are not. Education is also crucial on adopting the sense of road safety on children’s perspective. Simulation based studies have proved to be effective in order to draw child’s attention to the subject, however it should be combined with field trips to gain a more realistic and solid idea about the matter. Besides, engineering measures rise up as another milestone where roadside and land use planning is important. Traffic calming measures have proved to be effective to warn road users and thus form a safer traffic environment for children. Special applications for school zones such as flashing lights, narrowed crossways or 30km/h areas have been effective. The case study concerns the evaluation of child pedestrian safety in the vicinities of various accidents previously happened in Norrköping. Two methods were used to examine the degree of safety for the places of incidents. For locations near an intersection, road safety audit and traffic conflicts technique were applied, while, for the incident points along streets, only road safety audit technique was used. It is stated that, because of the multivariable aspect of the problem, collective application of various safety evaluation solutions would give better idea on the risk of the location and possible improvements for the future.

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Modern-day computer security relies heavily on cryptography as a means to protect the data that we have become increasingly reliant on. As the Internet becomes more ubiquitous, methods of security must be better than ever. Validation tools can be leveraged to help increase our confidence and accountability for methods we employ to secure our systems. Security validation, however, can be difficult and time-consuming. As our computational ability increases, calculations that were once considered “hard” due to length of computation, can now be done in minutes. We are constantly increasing the size of our keys and attempting to make computations harder to protect our information. This increase in “cracking” difficulty often has the unfortunate side-effect of making validation equally as difficult. We can leverage massive-parallelism and the computational power that is granted by today’s commodity hardware such as GPUs to make checks that would otherwise be impossible to perform, attainable. Our work presents a practical tool for validating RSA keys for poor prime numbers: a fundamental problem that has led to significant security holes, despite the RSA algorithm’s mathematical soundness. Our tool, PARIS, leverages NVIDIA’s CUDA framework to perform a complete set of greatest common divisor calculations between all keys in a provided set. Our implementation offers a 27.5 times speedup using a GTX 480 and 33.9 times speedup using a Tesla K20Xm: both compared to a reference sequential implementation for sets of less than 200000 keys. This level of speedup brings this validation into the realm of practicality due to decreased runtime.

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Given the ubiquity of media use, especially among young children, the current study examines the impact of problematic media use (PMU) on children's (N = 418, M age = 53.62 months, SD = 3.38 months, M and SD are taken from the full sample of 418 children) physiological functioning. With previous studies reporting relations between media use, temperament, and physiological regulation, it was hypothesized that children with greater levels of PMU would have lower levels of baseline respiratory sinus arrhythmia (RSA; a measure of physiological regulatory capacity). It is further hypothesized that, higher levels of negative affect, and lower levels of effortful control (two distinct domains of temperament) would be linked to both PMU and RSA and that temperament might mediate the associations between PMU and physiological regulation (RSA) (i.e., higher negative affect, lower effortful control linked to higher PMU and lower RSA). Data were drawn from Wave 5 of Project M.E.D.I.A, a longitudinal study of the effects of media on children's development. Findings revealed that PMU was significantly linked to lower baseline RSA for girls, but not for boys. Both boys' and girls' PMU was linked to higher levels of negative affect. Girls' PMU was linked to lower effortful control. The hypothesis that temperament would meditate links between PMU and RSA was not supported. The sex difference in the relation between PMU and baseline RSA are discussed, including potential differences in content of media girls are using as well as potential developmental differences for girls' reactivity compared to boys. Overall, PMU may lead to diminished physiological regulation, especially for girls, and appears to be linked to higher levels of negative affect in children. It is important for parents to be aware of the potential impact media use may have on their children's development.