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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Performance Evaluation and Comparison of Standard Cryptographic Algorithms and Chinese Cryptographic Algorithms

Bergman Martinkauppi, Louise, He, Qiuping January 2019 (has links)
Background. China is regulating the import, export, sale, and use of encryption technology in China. If any foreign company wants to develop or release a product in China, they need to report their use of any encryption technology to the Office of State Commercial Cryptography Administration (OSCCA) to gain approval. SM2, SM3, and SM4 are cryptographic standards published by OSCCA and are authorized to be used in China. To comply with Chinese cryptography laws organizations and companies may have to replace standard cryptographic algorithms in their systems with Chinese cryptographic algorithms, such as SM2, SM3, and SM4. It is important to know beforehand how the replacement of algorithms will impact performance to determine future system costs. Objectives. Perform a theoretical study and performance comparison of the standard cryptographic algorithms and Chinese Cryptographic algorithms. The standard cryptographic algorithms studied are RSA, ECDSA, SHA-256, and AES-128, and the Chinese cryptographic algorithms studied are SM2, SM3, and SM4. Methods. A literature analysis was conducted to gain knowledge and collect information about the selected cryptographic algorithms in order to make a theoretical comparison of the algorithms. An experiment was conducted to get measurements of how the algorithms perform and to be able to rate them. Results. The literature analysis provides a comparison that identifies design similarities and differences between the algorithms. The controlled experiment provides measurements of the metrics of the algorithms mentioned in objectives. Conclusions. The conclusions are that the digital signature algorithms SM2 and ECDSA have similar design and also similar performance. SM2 and RSA have fundamentally different designs, and SM2 performs better than RSA when generating keys and signatures. When verifying signatures, RSA shows comparable performance in some cases and worse performance in other cases. Hash algorithms SM3 and SHA-256 have many design similarities, but SHA-256 performs slightly better than SM3. AES-128 and SM4 have many similarities but also a few differences. In the controlled experiment, AES-128 outperforms SM4 with a significant margin. / Bakgrund. Kina reglerar import, export, försäljning och användning av krypteringsteknologi i Kina. Om ett utländskt företag vill utveckla eller släppa en produkt i Kina måste de rapportera sin användning av krypteringsteknologi till Office of State Commercial Cryptography Administration (OSCCA) för godkännande. SM2, SM3 och SM4 är kryptografiska standarder som lagligt får används i Kina. Organisationer och företag kan behöva byta ut krypteringsalgoritmerna i sina system till kinesiska krypteringsalgoritmer för att uppfylla kraven för de kinesiska lagarna. Det är därför viktigt att i förväg veta hur ersättningen av algoritmer kommer att påverka prestandan för att utvärdera framtida kostnader för systemet. Syfte. Genomföra en teoretisk studie och prestanda jämförelse av standard krypteringsalgoritmer och kinesiska krypteringsalgoritmer. De standard krypteringsalgoritmerna är RSA, ECDSA, SHA-256 och AES-128. De kinesiska krypteringsalgoritmerna är SM2, SM3 och SM4. Metod. En litteraturanalys har genomförts för att få en bättre förståelse av de valda algoritmerna. Ett experiment har genomförts för att samla mätvärden av de bestämda parametrarna och för att sedan kunna ranka mätvärdena. Resultat. Litteraturanalysen gav en jämförelse som identifierar likheter och skillnader mellan algoritmerna. Det kontrollerade experimentet gav mätvärden av parametrarna för algoritmerna nämnda i syftet. Slutsatser. Slutsatserna är att de digitala signatur-algoritmerna SM2 och ECDSA har liknade design och också liknade prestanda. SM2 och RSA har fundamentala skillnader i deras design, och SM2 har bättre prestanda vid nyckelgenerering samt signaturgenerering. Vid verifiering av signaturer så visar RSA likvärdig prestanda i vissa fall och sämre prestanda i andra fall. Hashfunktionerna SM3 och SHA-256 har också många likheter i sin design, men SHA-256 presterar lite bättre än SM3. AES-128 och SM3 har många design likheter men också några skillnader. I det kontrollerade experimentet så presterar AES-128 bättre än SM4 med stor marginal.
2

Constraints on the Fourth-Generation Quark Mixing Matrix from Precision Flavour Observables

Menzel, Andreas 27 February 2017 (has links)
Das Standardmodell einer zusätzlichen sequentiellen Fermiongeneration (SM4) war 2012 auf Basis eines Fits an elektroschwache Präzisionsobservable und die Higgs-Signalstärken mit einer Signifikanz von 5.3 sigma ausgeschlossen worden. Komplementär dazu wurden in der vorliegenden Arbeit Fits des SM4 an eine Kombination eines typischen Satzes von Flavour-Observablen mit den Ergebnissen des zuvor durchgeführten Elektroschwachen Präzisionsfits durchgeführt. Im SM3-Kontext extrahierte Größen wurden gemäß ihrer Bedeutung im SM4 reinterpretiert und die angepassten theoretischen Ausdrücke angegeben. Die resultierenden Einschränkungen der CKM-Matrix des SM4, ihrer potentiell CP-verletzenden Phasen sowie der Masse des up-type-Quarks der 4. Generation t'' werden angegeben. Zum Vergleich des SM4 mit dem SM3 werden die erreichten chi^2-Werte genutzt. chi^2=15.53 im SM4 und 9.56 im SM3 passen fast vollkommen zu einer gleich guten Beschreibung der Experimente durch beide Modelle, wobei das SM3 aber sechs Freiheitsgrade mehr besitzt. Außerdem wurden die Vorhersagen des SM3 und des SM4 für die Dimyon-Ladungsasymmetrie ASL mit experimentellen Werten verglichen. Die Vorhersage des SM3 ist ca. 2 sigma vom experimentellen Wert entfernt, die des SM4 ca. 3 sigma.\par Die Ergebnisse deuten nicht darauf hin, dass die Signifikanz des 2012 erreichten Ausschlusses des SM4 durch die Hinzunahme von Flavour-Observablen zu den damals verwendeten elektroschwachen Präzisionsobservablen und Higgs-Querschnitten bedeutend verringert würde.\par Es konnte jedoch keine genaue quantitative Aussage über die Auswirkungen der Flavourobservablen auf diese Signifikanz getroffen werden, weil das Programm CKMfitter likelihood-ratio-Berechnung nur durchführen kann, wenn sich eines der untersuchten Modelle durch Fixierung von Parametern aus dem anderen ergibt (nested models), was hier nicht der Fall ist. / The Standard Model extended by an additional sequential generation of Dirac fermions (SM4) was excluded with a significance of 5.3 sigma in 2012. This was achieved in a combined fit of the SM4 to Electroweak Precision Observables and signal strengths of the Higgs boson. This thesis complements this excludion by a fit of the SM4 to a typical set of Flavour physics observables and the results of the previously performed Electroweak Precision fit. Quantities extracted in an SM3 framework are reinterpreted in SM4 terms and the adapted theoretical expressions are given. The resultant constraints on the SM4''s CKM matrix, its potentially CP-violating phases and the mass of the new up-type quark t'' are given. To compare the relative performance of the SM4 and the SM3, this work uses the chi^2 values achieved in the fit. The values of 15.53 for the SM4 and 9.56 for the SM4 are almost perfectly consistent with both models describing the experimental data equally well with the SM3 having six degrees of freedom more. The dimuon charge asymmetry ASL was not used as a fit input because the interpretation of its measurement was subject to debate at the time when the fits were produced, but its prediction in the fit was used as an additional test of the SM4. The SM3''s prediction differs from the experimental values by about 2 sigma, and the SM4''s prediction by about 3 sigma. \par In summary, these results do not suggest that any significant reduction of the 5.3 sigma exclusion could be achieved by combining the Electroweak Precision Observables and Higgs inputs with Flavour physics data. However, the exact effect of the Flavour physics input on the significance of the SM4''s exclusion cannot be given at this point because the CKMfitter software is currently not able to perform a statistically stringent likelihood comparison of non-nested models.

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