{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:14:43Z","timestamp":1760058883384,"version":"build-2065373602"},"reference-count":45,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2025,5,1]],"date-time":"2025-05-01T00:00:00Z","timestamp":1746057600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cryptography"],"abstract":"<jats:p>Virtual reality (VR)\/the metaverse is transforming into a ubiquitous technology by leveraging smart devices to provide highly immersive experiences at an affordable price. Cryptographically securing such augmented reality schemes is of paramount importance. Securely transferring the same secret key, i.e., obfuscated, between several parties is the main issue with symmetric cryptography, the workhorse of modern cryptography, because of its ease of use and quick speed. Typically, asymmetric cryptography establishes a shared secret between parties, after which the switch to symmetric encryption can be made. However, several SoTA (State-of-The-Art) security research schemes lack flexibility and scalability for industrial Internet-of-Things (IoT)-sized applications. In this paper, we present the full architecture of the PRIVocular framework. PRIVocular (i.e., PRIV(acy)-ocular) is a VR-ready hardware\u2013software integrated system that is capable of visually transmitting user data over three versatile modes of encapsulation, encrypted\u2014without loss of generality\u2014using an asymmetric-key cryptosystem. These operation modes can be optical character-based or QR-tag-based. Encryption and decryption primarily depend on each mode\u2019s success ratio of correct encoding and decoding. We investigate the most efficient means of ocular (encrypted) data transfer by considering several designs and contributing to each framework component. Our pre-prototyped framework can provide such privacy preservation (namely virtual proof of privacy (VPP)) and visually secure data transfer promptly (&lt;1000 ms), as well as the physical distance of the smart glasses (\u223c50 cm).<\/jats:p>","DOI":"10.3390\/cryptography9020029","type":"journal-article","created":{"date-parts":[[2025,5,1]],"date-time":"2025-05-01T09:16:12Z","timestamp":1746090972000},"page":"29","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["PRIVocular: Enhancing User Privacy Through Air-Gapped Communication Channels"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6236-1707","authenticated-orcid":false,"given":"Anastasios N.","family":"Bikos","sequence":"first","affiliation":[{"name":"Department of Computer Engineering and Informatics, University of Patras, 26504 Patras, Greece"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Kuty\u0142owski, M., and Vaidya, J. (2014). Ubic: Bridging the Gap between Digital Cryptography and the Physical World. Computer Security\u2014ESORICS 2014, Springer. ESORICS 2014, Lecture Notes in Computer Science.","DOI":"10.1007\/978-3-319-11203-9"},{"key":"ref_2","unstructured":"(2025, April 18). Reality 51 Team Managed by \u0141ukasz Rosi\u0144ski, The Farm 51 Group S.A., Report on the Current State of the VR Market. Available online: http:\/\/thefarm51.com\/ripress\/VR_market_report_2015_The_Farm51.pdf."},{"key":"ref_3","unstructured":"Holley, R. (2014, January 05). How Good Can It Get? Analysing and Improving OCR Accuracy in Large Scale Historic Newspaper Digitisation Programs. D-Lib Magazine. Available online: https:\/\/www.dlib.org\/dlib\/march09\/holley\/03holley.html."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Smith, R. (2007, January 23\u201326). An Overview of the Tesseract OCR Engine. Proceedings of the Ninth International Conference on Document Analysis and Recognition (ICDAR 2007), Curitiba, Parana.","DOI":"10.1109\/ICDAR.2007.4376991"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Mantoro, T., Sobri, A.M., and Usino, W. (2013, January 23\u201324). Optical Character Recognition (OCR) Performance in Server-Based Mobile Environment. Proceedings of the 2013 International Conference on Advanced Computer Science Applications and Technologies, Kuching, Malaysia.","DOI":"10.1109\/ACSAT.2013.89"},{"key":"ref_6","unstructured":"Shen, M., and Lei, H. (2015, January 15\u201317). Improving OCR performance with background image elimination. Proceedings of the 2015 12th International Conference on Fuzzy Systems and Knowledge Discovery (FSKD), Zhangjiajie, China."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Ramiah, S., Liong, T.Y., and Jayabalan, M. (2015, January 13\u201314). Detecting text based image with optical character recognition for English translation and speech using Android. Proceedings of the 2015 IEEE Student Conference on Research and Development (SCOReD), Kuala Lumpur, Malaysia.","DOI":"10.1109\/SCORED.2015.7449339"},{"key":"ref_8","unstructured":"From QR Code.com (2016, May 23). Denso-Wave. \u201cQR Code Standardization\u201d. Available online: http:\/\/www.qrcode.com\/en\/about\/standards.html."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Sadikin, M.A., and Sunaringtyas, S.U. (2016, January 5\u20136). Implementing digital signature for the secure electronic prescription using QR-code based on Android smartphone. Proceedings of the 2016 International Seminar on Application for Technology of Information and Communication (ISemantic), Semarang, Indonesia.","DOI":"10.1109\/ISEMANTIC.2016.7873856"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Rodrigues, B., Chaudhari, A., and More, S. (2016, January 14\u201317). Two factor verification using QR-code: A unique authentication system for Android smartphone users. Proceedings of the 2nd International Conference on Contemporary Computing and Informatics (IC3I), Greater Noida, India.","DOI":"10.1109\/IC3I.2016.7918008"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Jagodi\u0107, D., Vuji\u0109i\u0107, D., and Ran\u0111i\u0107, S. (2015, January 24\u201326). Android system for identification of objects based on QR code. Proceedings of the 2015 23rd Telecommunications Forum Telfor (TELFOR), Belgrade, Serbia.","DOI":"10.1109\/TELFOR.2015.7377616"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Divya, R., and Muthukumarasamy, S. (2015, January 9\u201310). An impervious QR-based visual authentication protocols to prevent black-bag cryptanalysis. Proceedings of the 2015 IEEE 9th International Conference on Intelligent Systems and Control (ISCO), Coimbatore, India.","DOI":"10.1109\/ISCO.2015.7282330"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Patil, D., and Guru, S.K. (2014, January 27\u201328). Secured authentication using challenge-response and quick-response code for Android mobiles. Proceedings of the International Conference on Information Communication and Embedded Systems (ICICES2014), Chennai, India.","DOI":"10.1109\/ICICES.2014.7033865"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Bani-Hani, R.M., Wahsheh, Y.A., and Al-Sarhan, M.B. (2014, January 9\u201311). Secure QR code system. Proceedings of the 2014 10th International Conference on Innovations in Information Technology (IIT), Al Ain, United Arab Emirates.","DOI":"10.1109\/INNOVATIONS.2014.6985772"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Dey, S., Nath, A., and Agarwal, S. (2013, January 6\u20138). Confidential Encrypted Data Hiding and Retrieval Using QR Authentication System. Proceedings of the 2013 International Conference on Communication Systems and Network Technologies, Gwalior, India.","DOI":"10.1109\/CSNT.2013.112"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Ravi, R.V., Dutta, P.K., and Roy, S. (2023). Color Image Cryptography Using Block and Pixel-Wise Permutations with 3D Chaotic Diffusion in Metaverse. International Conferences on Artificial Intelligence and Computer Vision, Springer.","DOI":"10.1007\/978-3-031-27762-7_29"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"De Lorenzis, F., Visconti, A., Marani, M., Prifti, E., Andiloro, C., Cannav\u00f2, A., and Lamberti, F. (2023, January 19\u201322). 3DK-Reate: Create Your Own 3D Key for Distributed Authentication in the Metaverse. Proceedings of the 2023 IEEE Gaming, Entertainment, and Media Conference (GEM), Bridgetown, Barbados.","DOI":"10.1109\/GEM59776.2023.10390314"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1007\/s44206-024-00128-9","article-title":"Eye-Tracking Devices for Virtual and Augmented Reality Metaverse Environments and Their Compatibility with the European Union General Data Protection Regulation","volume":"3","author":"Bozkir","year":"2024","journal-title":"Digit. Soc."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Lin, C.-C., Nshimiyimana, A., SaberiKamarposhti, M., and Elbasi, E. (2024). Authentication Framework for Augmented Reality with Data-Hiding Technique. Symmetry, 16.","DOI":"10.3390\/sym16101253"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"El-Hajj, M. (2025). Cybersecurity and Privacy Challenges in Extended Reality: Threats, Solutions, and Risk Mitigation Strategies. Virtual Worlds, 4.","DOI":"10.3390\/virtualworlds4010001"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Cruz, A.C., Costa, R.L.d.C., Santos, L., Rabad\u00e3o, C., Marto, A., and Gon\u00e7alves, A. (2025). Assessing User Perceptions and Preferences on Applying Obfuscation Techniques for Privacy Protection in Augmented Reality. Future Internet, 17.","DOI":"10.3390\/fi17020055"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Paillier, P. (1999). Public-Key Cryptosystems Based on Composite Degree Residuosity Classes. EUROCRYPT 1999, Springer.","DOI":"10.1007\/3-540-48910-X_16"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2123","DOI":"10.1109\/TIFS.2016.2569062","article-title":"Cryptoleq: A Heterogeneous Abstract Machine for Encrypted and Unencrypted Computation","volume":"11","author":"Mazonka","year":"2016","journal-title":"IEEE Trans. Inf. Forensics Secur."},{"key":"ref_24","unstructured":"(2025, April 18). Android Developers. Available online: https:\/\/developer.android.com\/index.html."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Massandy, D.T., and Munir, I.R. (2012, January 30\u201331). Secured video streaming development on smartphones with Android platform. Proceedings of the 2012 7th International Conference on Telecommunication Systems, Services, and Applications (TSSA), Denpasar-Bali, Indonesia.","DOI":"10.1109\/TSSA.2012.6366079"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Starnberger, G., Froihofer, L., and Goeschka, K.M. (2009, January 16\u201319). Qr-tan: Secure mobile transaction authentication. Proceedings of the 2012 Seventh International Conference on Availability, Reliability and Security, Fukuoka, Japan.","DOI":"10.1109\/ARES.2009.96"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1757","DOI":"10.1109\/18.782097","article-title":"Improved decoding of Reed-Solomon codes and algebraic geometry codes","volume":"45","author":"Guruswami","year":"1999","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Li, K.-C., Gupta, B.B., and Agrawal, D.P. (2020). The Future of Privacy and Trust on the Internet of Things (IoT) for Healthcare: Concepts, Challenges, and Security Threat Mitigations. Recent Advances in Security, Privacy, and Trust for Internet of Things (IoT) and Cyber- Physical Systems (CPS), CRC Press.","DOI":"10.1201\/9780429270567"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Chan, T.H., Ho, S.W., and Yamamoto, H. (2015, January 14\u201319). Private information retrieval for coded storage. Proceedings of the 2015 IEEE International Symposium on Information Theory (ISIT), Hong Kong, China.","DOI":"10.1109\/ISIT.2015.7282975"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Kamara, S., and Papamanthou, C. (2013, January 1\u20135). Parallel and Dynamic Searchable Symmetric Encryption. Proceedings of the Financial Cryptography and Data Security\u201417th International Conference, FC 2013, Okinawa, Japan.","DOI":"10.1007\/978-3-642-39884-1_22"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1125","DOI":"10.1109\/TKDE.2012.90","article-title":"Single-Database Private Information Retrieval from Fully Homomorphic Encryption","volume":"25","author":"Yi","year":"2013","journal-title":"IEEE Trans. Knowl. Data Eng."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"415","DOI":"10.4103\/jehp.jehp_667_24","article-title":"The Metaverse: An efficient and adaptable virtual reality platform for medical education and treatment","volume":"13","author":"Pawar","year":"2024","journal-title":"J. Educ. Health Promot."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Jana, S., Narayanan, A., and Shmatikov, V. (2013, January 19\u201322). A scanner darkly: Protecting user privacy from perceptual applications. Proceedings of the IEEE Symposium on Security and Privacy, Berkeley, CA, USA.","DOI":"10.1109\/SP.2013.31"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"B\u00e1lint, Z., Kiss, B., Magyari, B., and Simon, K. (2012, January 20\u201322). Augmented reality and image recognition based framework for treasure hunt games. Proceedings of the 2012 IEEE 10th Jubilee International Symposium on Intelligent Systems and Informatics, Subotica, Serbia.","DOI":"10.1109\/SISY.2012.6339504"},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Du, R., Lee, E., and Varshney, A. (2019, January 23\u201327). Tracking-Tolerant Visual Cryptography. Proceedings of the 2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), Osaka, Japan.","DOI":"10.1109\/VR.2019.8797924"},{"key":"ref_36","unstructured":"Gao, Y. (2015). Secure Key Exchange Protocol based on Virtual Proof of Reality. IACR Cryptol. ePrint Arch., 524."},{"key":"ref_37","first-page":"1","article-title":"Extended Privacy for Extended Reality: XR Technology Has 99 Problems and Privacy Is Several of Them","volume":"4","author":"Pahi","year":"2023","journal-title":"Notre Dame J. Emerg. Tech."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Jones, D., Ghasemi, S., Gra\u010danin, D., and Azab, M. (2023). Privacy, safety, and security in extended reality: User experience challenges for neurodiverse users. HCI for Cybersecurity, Privacy and Trust, Proceedings of the International Conference on Human-Computer Interaction, Copenhagen, Denmark, 23\u201328 July 2023, Springer.","DOI":"10.1007\/978-3-031-35822-7_33"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Warin, C., and Reinhardt, D. (2022, January 29\u201330). Vision: Usable Privacy for XR in the Era of the Metaverse. Proceedings of the 2022 European Symposium on Usable Security, Karlsruhe, Germany.","DOI":"10.1145\/3549015.3554212"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Acheampong, R., Balan, T.C., Popovici, D.M., and Rekeraho, A. (2023). Embracing XR System Without Compromising on Security and Privacy. Extended Reality, Proceedings of the International Conference on Extended Reality, Lecce, Italy, 6\u20139 September 2023, Springer.","DOI":"10.1007\/978-3-031-43401-3_7"},{"key":"ref_41","unstructured":"(2025, April 18). GitHub Qrcode-Terminal. Available online: https:\/\/github.com\/gtanner\/qrcode-terminal."},{"key":"ref_42","unstructured":"Kanai, J., Nartker, T.A., Rice, S., and Nagy, G. (1993, January 20\u201322). Performance metrics for document understanding systems. Proceedings of the Second International Conference on Document Analysis and Recognition, Tsukuba Science City, Japan."},{"key":"ref_43","unstructured":"(2025, April 18). Official ZXing (\u201cZebra Crossing\u201d) Project Home. Available online: https:\/\/github.com\/zxing\/zxing."},{"key":"ref_44","unstructured":"Stefanov, E., Shi, E., and Song, D. (2012, January 5\u20138). Towards practical oblivious RAM. Proceedings of the NDSS 2012, San Diego, CA, USA."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Canbay, Y., Utku, A., and Canbay, P. (2022, January 19\u201320). Privacy Concerns and Measures in Metaverse: A Review. Proceedings of the 2022 15th International Conference on Information Security and Cryptography (ISCTURKEY), Ankara, Turkey.","DOI":"10.1109\/ISCTURKEY56345.2022.9931866"}],"container-title":["Cryptography"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2410-387X\/9\/2\/29\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:26:06Z","timestamp":1760030766000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2410-387X\/9\/2\/29"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,1]]},"references-count":45,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2025,6]]}},"alternative-id":["cryptography9020029"],"URL":"https:\/\/doi.org\/10.3390\/cryptography9020029","relation":{},"ISSN":["2410-387X"],"issn-type":[{"type":"electronic","value":"2410-387X"}],"subject":[],"published":{"date-parts":[[2025,5,1]]}}}