{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T18:06:44Z","timestamp":1782410804624,"version":"3.54.5"},"reference-count":51,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2015,4,3]],"date-time":"2015-04-03T00:00:00Z","timestamp":1428019200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>The imperative need for unconditional secure key exchange is expounded by the increasing connectivity of networks and by the increasing number and level of sophistication of cyberattacks. Two concepts that are theoretically information-secure are quantum key distribution (QKD) and Kirchoff-Law-Johnson-Noise (KLJN). However, these concepts require a dedicated connection between hosts in peer-to-peer (P2P) networks which can be impractical and or cost prohibitive. A practical and cost effective method is to have each host share their respective cable(s) with other hosts such that two remote hosts can realize a secure key exchange without the need of an additional cable or key exchanger. In this article we analyze the cost complexities of cable, key exchangers, and time required in the star network. We mentioned the reliability of the star network and compare it with other network geometries. We also conceived a protocol and equation for the number of secure bit exchange periods needed in a star network. We then outline other network geometries and trade-off possibilities that seem interesting to explore.<\/jats:p>","DOI":"10.3390\/e17042010","type":"journal-article","created":{"date-parts":[[2015,4,7]],"date-time":"2015-04-07T03:47:46Z","timestamp":1428378466000},"page":"2010-2024","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Resource Requirements and Speed versus Geometry of Unconditionally Secure Physical Key Exchanges"],"prefix":"10.3390","volume":"17","author":[{"given":"Elias","family":"Gonzalez","sequence":"first","affiliation":[{"name":"Department of Electrical and Computer Engineering, Texas A&M University, 3128 TAMU College Station, TX 77843, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robert","family":"Balog","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Texas A&M University, 3128 TAMU College Station, TX 77843, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laszlo","family":"Kish","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Texas A&M University, 3128 TAMU College Station, TX 77843, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2015,4,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1109\/TITS.2004.838218","article-title":"Challenges of intervehicle ad hoc networks","volume":"5","author":"Blum","year":"2004","journal-title":"IEEE Trans. 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