Pub Date : 2021-06-02DOI: 10.33048/semi.2021.18.063
A. Gorodilova, N. Tokareva, S. Agievich, C. Carlet, V. Idrisova, K. Kalgin, D. Kolegov, A. Kutsenko, N. Mouha, M. Pudovkina, A. Udovenko
The International Olympiad in Cryptography NSUCRYPTO is the unique Olympiad containing scientific mathematical problems for professionals, school and university students from any country. Its aim is to involve young researchers in solving curious and tough scientific problems of modern cryptography. In 2020, it was held for the seventh time. Prizes and diplomas were awarded to 84 participants in the first round and 49 teams in the second round from 32 countries. In this paper, problems and their solutions of NSUCRYPTO'2020 are presented. We consider problems related to attacks on ciphers and hash functions, protocols, permutations, primality tests, etc. We discuss several open problems on JPEG encoding, Miller -- Rabin primality test, special bases in the vector space, AES-GCM. The problem of a modified Miller -- Rabin primality test was solved during the Olympiad. The problem for finding special bases was partially solved.
{"title":"The Seventh International Olympiad in Cryptography: Problems and solutions","authors":"A. Gorodilova, N. Tokareva, S. Agievich, C. Carlet, V. Idrisova, K. Kalgin, D. Kolegov, A. Kutsenko, N. Mouha, M. Pudovkina, A. Udovenko","doi":"10.33048/semi.2021.18.063","DOIUrl":"https://doi.org/10.33048/semi.2021.18.063","url":null,"abstract":"The International Olympiad in Cryptography NSUCRYPTO is the unique Olympiad containing scientific mathematical problems for professionals, school and university students from any country. Its aim is to involve young researchers in solving curious and tough scientific problems of modern cryptography. In 2020, it was held for the seventh time. Prizes and diplomas were awarded to 84 participants in the first round and 49 teams in the second round from 32 countries. In this paper, problems and their solutions of NSUCRYPTO'2020 are presented. We consider problems related to attacks on ciphers and hash functions, protocols, permutations, primality tests, etc. We discuss several open problems on JPEG encoding, Miller -- Rabin primality test, special bases in the vector space, AES-GCM. The problem of a modified Miller -- Rabin primality test was solved during the Olympiad. The problem for finding special bases was partially solved.","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49434689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-02DOI: 10.33048/semi.2021.18.043
A. Kozhanov, N. Shadrina
{"title":"Boundary value problems with conjugation conditions for quasi-parabolic equations of the third order with a discontinuous sign-variable coefficient","authors":"A. Kozhanov, N. Shadrina","doi":"10.33048/semi.2021.18.043","DOIUrl":"https://doi.org/10.33048/semi.2021.18.043","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44365050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-02DOI: 10.33048/semi.2021.18.044
A. Mednykh
{"title":"Fixed points of cyclic groups acting purely harmonically on a graph","authors":"A. Mednykh","doi":"10.33048/semi.2021.18.044","DOIUrl":"https://doi.org/10.33048/semi.2021.18.044","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45769528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-26DOI: 10.33048/semi.2021.18.042
N. Pertsev
{"title":"Construction of exponentially decreasing estimates of solutions to a Cauchy problem for some nonlinear systems of delay differential equations","authors":"N. Pertsev","doi":"10.33048/semi.2021.18.042","DOIUrl":"https://doi.org/10.33048/semi.2021.18.042","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47630273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-25DOI: 10.33048/semi.2021.18.040
A. K. Bazzaev, D. K. Gutnova
{"title":"About convergence of difference schemes for a third-order pseudo-parabolic equation with nonlocal boundary value condition","authors":"A. K. Bazzaev, D. K. Gutnova","doi":"10.33048/semi.2021.18.040","DOIUrl":"https://doi.org/10.33048/semi.2021.18.040","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47193134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-19DOI: 10.33048/semi.2021.18.038
V. D. Plaksina, P. Shcherbina
{"title":"New perfect colorings of infinite circulant graphs with continuous sets of distances","authors":"V. D. Plaksina, P. Shcherbina","doi":"10.33048/semi.2021.18.038","DOIUrl":"https://doi.org/10.33048/semi.2021.18.038","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46122871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-18DOI: 10.33048/semi.2021.18.037
T. I. Fedoryaeva
{"title":"Center and its spectrum of almost all $n$-vertex graphs of given diameter","authors":"T. I. Fedoryaeva","doi":"10.33048/semi.2021.18.037","DOIUrl":"https://doi.org/10.33048/semi.2021.18.037","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49361299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-12DOI: 10.33048/semi.2021.18.035
Z. K. Ivanova, M. Faizrahmanov
{"title":"Weak reducibility of computable and generalized computable numberings","authors":"Z. K. Ivanova, M. Faizrahmanov","doi":"10.33048/semi.2021.18.035","DOIUrl":"https://doi.org/10.33048/semi.2021.18.035","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44918281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-28DOI: 10.33048/semi.2021.18.033
T. Yuldashev, F. Mukhamadiev
{"title":"Local $tau$-density and local weak $tau$-density in topological spaces","authors":"T. Yuldashev, F. Mukhamadiev","doi":"10.33048/semi.2021.18.033","DOIUrl":"https://doi.org/10.33048/semi.2021.18.033","url":null,"abstract":"","PeriodicalId":45858,"journal":{"name":"Siberian Electronic Mathematical Reports-Sibirskie Elektronnye Matematicheskie Izvestiya","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48892727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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