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Estatal de Investigaci\u00f3n\u2014AEI","award":["101119746"],"award-info":[{"award-number":["101119746"]}]},{"name":"Spanish Agencia Estatal de Investigaci\u00f3n\u2014AEI","award":["101017733"],"award-info":[{"award-number":["101017733"]}]},{"name":"Spanish Agencia Estatal de Investigaci\u00f3n\u2014AEI","award":["101114043"],"award-info":[{"award-number":["101114043"]}]},{"name":"European Union\u2019s Horizon Europe research and innovation funding program","award":["PRTR-C17.I1"],"award-info":[{"award-number":["PRTR-C17.I1"]}]},{"name":"European Union\u2019s Horizon Europe research and innovation funding program","award":["101119746"],"award-info":[{"award-number":["101119746"]}]},{"name":"European Union\u2019s Horizon Europe research and innovation funding program","award":["101017733"],"award-info":[{"award-number":["101017733"]}]},{"name":"European Union\u2019s Horizon Europe research and innovation funding program","award":["101114043"],"award-info":[{"award-number":["101114043"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Quantum-key-distribution (QKD) networks are gaining importance and it has become necessary to analyze the most appropriate methods for their long-distance interconnection. In this paper, four different methods of interconnecting remote QKD networks are proposed. The methods are used to link three different QKD testbeds in Europe, located in Berlin, Madrid, and Poznan. Although long-distance QKD links are only emulated, the methods used can serve as a blueprint for the secure interconnection of distant QKD networks in the future. Specifically, the presented approaches combine, in a transparent way, different fiber and satellite physical media, as well as common standards of key delivery interfaces. The testbed interconnections are designed to increase the security by utilizing multipath techniques and multiple hybridizations of QKD and post-quantum cryptography (PQC) algorithms.<\/jats:p>","DOI":"10.3390\/e26020123","type":"journal-article","created":{"date-parts":[[2024,1,31]],"date-time":"2024-01-31T08:44:06Z","timestamp":1706690646000},"page":"123","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Linking QKD Testbeds across Europe"],"prefix":"10.3390","volume":"26","author":[{"given":"Max","family":"Brauer","sequence":"first","affiliation":[{"name":"T-Labs, Deutsche Telekom AG, 10781 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6334-639X","authenticated-orcid":false,"given":"Rafael J.","family":"Vicente","sequence":"additional","affiliation":[{"name":"DLSIIS and Center for Computational Simulation, Universidad Polit\u00e9cnica de Madrid, 28660 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9502-9978","authenticated-orcid":false,"given":"Jaime S.","family":"Buruaga","sequence":"additional","affiliation":[{"name":"DLSIIS and Center for Computational Simulation, Universidad Polit\u00e9cnica de Madrid, 28660 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rub\u00e9n B.","family":"M\u00e9ndez","sequence":"additional","affiliation":[{"name":"DLSIIS and Center for Computational Simulation, Universidad Polit\u00e9cnica de Madrid, 28660 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9433-5391","authenticated-orcid":false,"given":"Ralf-Peter","family":"Braun","sequence":"additional","affiliation":[{"name":"T-Labs, Deutsche Telekom AG, 10781 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marc","family":"Geitz","sequence":"additional","affiliation":[{"name":"T-Labs, Deutsche Telekom AG, 10781 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5050-742X","authenticated-orcid":false,"given":"Piotr","family":"Rydlichkowski","sequence":"additional","affiliation":[{"name":"Poznan Supercomputing and Networking Center, 61-139 Pozna\u0144, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hans H.","family":"Brunner","sequence":"additional","affiliation":[{"name":"Munich Research Center, Huawei Technologies Duesseldorf GmbH, 80992 Munich, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fred","family":"Fung","sequence":"additional","affiliation":[{"name":"Munich Research Center, Huawei Technologies Duesseldorf GmbH, 80992 Munich, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7928-0409","authenticated-orcid":false,"given":"Momtchil","family":"Peev","sequence":"additional","affiliation":[{"name":"Munich Research Center, Huawei Technologies Duesseldorf GmbH, 80992 Munich, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antonio","family":"Pastor","sequence":"additional","affiliation":[{"name":"Telef\u00f3nica gCTIO\/I+D, 28050 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8326-2000","authenticated-orcid":false,"given":"Diego R.","family":"Lopez","sequence":"additional","affiliation":[{"name":"Telef\u00f3nica gCTIO\/I+D, 28050 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vicente","family":"Martin","sequence":"additional","affiliation":[{"name":"DLSIIS and Center for Computational Simulation, Universidad Polit\u00e9cnica de Madrid, 28660 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan P.","family":"Brito","sequence":"additional","affiliation":[{"name":"DLSIIS and Center for Computational Simulation, Universidad Polit\u00e9cnica de Madrid, 28660 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,1,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1137\/S0036144598347011","article-title":"Polynomial-time algorithms for prime factorization and discrete logarithms on a quantum computer","volume":"41","author":"Shor","year":"1999","journal-title":"SIAM Rev."},{"key":"ref_2","unstructured":"Moody, D. 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