{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,11]],"date-time":"2026-04-11T07:55:11Z","timestamp":1775894111787,"version":"3.50.1"},"reference-count":23,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2014,11,19]],"date-time":"2014-11-19T00:00:00Z","timestamp":1416355200000},"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>Privacy and security are very important in vehicular ad hoc networks (VANETs). VANETs are negatively affected by any malicious user\u2019s behaviors, such as bogus information and replay attacks on the disseminated messages. Among various security threats, privacy preservation is one of the new challenges of protecting users\u2019 private information. Existing authentication protocols to secure VANETs raise challenges, such as certificate distribution and reduction of the strong reliance on tamper-proof devices. In 2011, Yeh et al. proposed a PAACP: a portable privacy-preserving authentication and access control protocol in vehicular ad hoc networks. However, PAACP in the authorization phase is breakable and cannot maintain privacy in VANETs. In this paper, we present a cryptanalysis of an attachable blind signature and demonstrate that the PAACP\u2019s authorized credential (AC) is not secure and private, even if the AC is secretly stored in a tamper-proof device. An eavesdropper can construct an AC from an intercepted blind document. Any eavesdropper can determine who has which access privileges to access which service. For this reason, this paper copes with these challenges and proposes an efficient scheme. We conclude that an improving authentication scheme and access control protocol for VANETs not only resolves the problems that have appeared, but also is more secure and efficient.<\/jats:p>","DOI":"10.3390\/e16116152","type":"journal-article","created":{"date-parts":[[2014,11,19]],"date-time":"2014-11-19T10:56:41Z","timestamp":1416394601000},"page":"6152-6165","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Improving the Authentication Scheme and Access Control Protocol for VANETs"],"prefix":"10.3390","volume":"16","author":[{"given":"Wei-Chen","family":"Wu","sequence":"first","affiliation":[{"name":"Computer Center, Hsin Sheng Junior College of Medical Care and Management, No. 418, Kaoping Village, Lungtan Township, Taoyuan County 32544, Taiwan"},{"name":"Department of Information Management, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yi-Ming","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Information Management, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2014,11,19]]},"reference":[{"key":"ref_1","first-page":"23","article-title":"Lightweight anonymous authentication scheme with unlinkability in global mobility networks","volume":"4","author":"Chung","year":"2013","journal-title":"J. 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