{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T11:28:25Z","timestamp":1775734105850,"version":"3.50.1"},"reference-count":50,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2019,2,18]],"date-time":"2019-02-18T00:00:00Z","timestamp":1550448000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005981","name":"Direktorat Jenderal Pendidikan Tinggi","doi-asserted-by":"publisher","award":["160023117803"],"award-info":[{"award-number":["160023117803"]}],"id":[{"id":"10.13039\/501100005981","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Limitations of the computational and energy capabilities of IoT devices provide new challenges in securing communication between devices. Physical layer security (PHYSEC) is one of the solutions that can be used to solve the communication security challenges. In this paper, we conducted an investigation on PHYSEC which utilizes channel reciprocity in generating a secret key, commonly known as secret key generation (SKG) schemes. Our research focused on the efforts to get a simple SKG scheme by eliminating the information reconciliation stage so as to reduce the high computational and communication cost. We exploited the pre-processing method by proposing a modified Kalman (MK) and performing a combination of the method with a multilevel quantization, i.e., combined multilevel quantization (CMQ). Our approach produces a simple SKG scheme for its significant increase in reciprocity so that an identical secret key between two legitimate users can be obtained without going through the information reconciliation stage.<\/jats:p>","DOI":"10.3390\/e21020192","type":"journal-article","created":{"date-parts":[[2019,2,19]],"date-time":"2019-02-19T04:08:20Z","timestamp":1550549300000},"page":"192","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":35,"title":["A Simple Secret Key Generation by Using a Combination of Pre-Processing Method with a Multilevel Quantization"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8751-560X","authenticated-orcid":false,"given":"Mike","family":"Yuliana","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering, Faculty of Electrical Technology, Institut Teknologi Sepuluh Nopember, Jalan Raya ITS, Keputih, Sukolilo, Surabaya 60111, Indonesia"},{"name":"Department of Electrical Engineering, Politeknik Elektronika Negeri Surabaya (PENS), Jalan Raya ITS, Keputih, Sukolilo, Surabaya 60111, Indonesia"}]},{"family":"Wirawan","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Faculty of Electrical Technology, Institut Teknologi Sepuluh Nopember, Jalan Raya ITS, Keputih, Sukolilo, Surabaya 60111, Indonesia"}]},{"family":"Suwadi","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Faculty of Electrical Technology, Institut Teknologi Sepuluh Nopember, Jalan Raya ITS, Keputih, Sukolilo, Surabaya 60111, Indonesia"}]}],"member":"1968","published-online":{"date-parts":[[2019,2,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1177\/1550147716665500","article-title":"Internet of Vehicles: From intelligent grid to autonomous cars and vehicular fogs","volume":"12","author":"Lee","year":"2016","journal-title":"Int. J. Distrib. Sens. Netw."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Mora, H., Gil, D., and Szymanski, J. (2017). An IoT-Based Computational Framework for Healthcare Monitoring in Mobile Environments. Sensors, 17.","DOI":"10.3390\/s17102302"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Diaz-cacho, M., Delgado, E., Falcon, P., and Barreiro, A. (2015, January 27\u201329). IoT integration on Industrial Environments. Proceedings of the IEEE World Conference on Factory Communication Systems (WFCS), Palma de Mallorca, Spain.","DOI":"10.1109\/WFCS.2015.7160553"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Yadav, V., and Borate, S. (2017, January 7\u20139). Smart Home Automation using Virtue of IoT. Proceedings of the International Conference for Convergence in Technology (I2CT), Mumbai, India.","DOI":"10.1109\/I2CT.2017.8226143"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Zhang, J., Duong, T.Q., Woods, R., and Marshall, A. (2017). Securing wireless communications of the internet of things from the physical layer, an overview. Entropy, 19.","DOI":"10.3390\/e19080420"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Margelis, G., Fafoutis, X., Oikonomou, G., Piechocki, R., Tryfonas, R., and Thomas, P. (2018). Efficient DCT-based secret key generation for the Internet of Things. Ad Hoc Netw., 1\u201311.","DOI":"10.1016\/j.adhoc.2018.08.014"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1814","DOI":"10.1109\/JPROC.2015.2459592","article-title":"Wireless Physical-Layer Security: Lessons Learned from Information Theory","volume":"103","author":"Yener","year":"2015","journal-title":"Proc. IEEE"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Carbajal-gomez, V.H., Tlelo-cuautle, E., Mu, J.M., Gerardo, L., Fraga, D., Sanchez-lopez, C., and Fernandez-fernandez, F.V. (2018). Optimization and CMOS design of chaotic oscillators robust to PVT variations: INVITED. Integration.","DOI":"10.1016\/j.vlsi.2018.10.010"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1002\/sat.1033","article-title":"A simple key agreement scheme based on chaotic maps for VSAT satellite communications","volume":"31","author":"Lee","year":"2013","journal-title":"Int. J. Satell. Commun. Netw."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"735","DOI":"10.1007\/s12243-009-0096-z","article-title":"A new authenticated group key agreement in a mobile environment","volume":"64","author":"Lin","year":"2009","journal-title":"Ann. Telecommun."},{"key":"ref_11","unstructured":"Menezes, A.J., Oorschot, P.C.V., and Vanstone, S.A. (1996). Handbook of Applied Cryptography, CRC Press. [1st ed.]."},{"key":"ref_12","unstructured":"Stallings, W. (2013). Cryptography and Network Security: Principles and Practice, Prentice Hall Press. [6th ed.]."},{"key":"ref_13","first-page":"116","article-title":"Securing the Internet of Things in a Quantum World","volume":"55","author":"Cheng","year":"2017","journal-title":"IEEE Commun. Mag."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Padamvathi, V., Vardhan, B.V., and Krishna, A.V.N. (2016, January 27\u201328). Quantum Cryptography and Quantum Key Distribution Protocols: A Survey. Proceedings of the 6th International Conference on Advanced Computing (IACC), Bhimavaram, India.","DOI":"10.1109\/IACC.2016.109"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Wang, Y., and She, K.A. (2017, January 21\u201323). practical quantum public-key encryption model. Proceedings of the 3rd International Conference on Information Management (ICIM), Chengdu, China.","DOI":"10.1109\/INFOMAN.2017.7950410"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"614","DOI":"10.1109\/ACCESS.2016.2521718","article-title":"Key Generation from Wireless Channels: A Review","volume":"4","author":"Zhang","year":"2016","journal-title":"IEEE Access"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Rodr\u00edguez-orozco, E., Garc\u00ed-guerrero, E., Inzunza-gonzalez, E., L\u00f3pez-bonilla, O.R., Flores-vergara, A., C\u00e1denas-valdez, J.R., and Tlelo-Cuautle, E. (2018). FPGA-based Chaotic Cryptosystem by Using Voice Recognition as Access Key. Electronics, 7.","DOI":"10.3390\/electronics7120414"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Sun, L., and Du, Q.A. (2018). Review of Physical Layer Security Techniques for Internet of Things: Challenges and Solutions. Entropy, 20.","DOI":"10.3390\/e20100730"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Zenger, C.T., Zimmer, J., Pietersz, M., Posielek, J.-F., and Paar, C. (2015, January 8\u201311). Exploiting the Physical Environment for Securing the Internet of Things. Proceedings of the New Secur. Paradig, Work (NSPW), Twente, The Netherlands.","DOI":"10.1145\/2841113.2841117"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Pecorella, T., Brilli, L., and Mucchi, L. (2016). The Role of Physical Layer Security in IoT: A Novel Perspective. Indormation, 7.","DOI":"10.3390\/info7030049"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1747","DOI":"10.1109\/JPROC.2015.2466548","article-title":"Physical-Layer Security in the Internet of Things: Sensing and Communication Confidentiality under Resource Constraints","volume":"103","author":"Mukherjee","year":"2015","journal-title":"Proc. IEEE"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"4464","DOI":"10.1109\/ACCESS.2016.2604618","article-title":"Experimental Study on Key Generation for Physical Layer Security in Wireless Communications","volume":"4","author":"Zhang","year":"2016","journal-title":"IEEE Access"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Guillaume, R., Winzer, F., Zenger, C.T., Paar, C., and Czylwik, A. (2015, January 6\u20139). Bringing PHY-based key generation into the field: An evaluation for practical scenarios. Proceedings of the 82nd 2015 IEEE 82nd Vehicular Technology Conference (VTC2015-Fall), Boston, MA, USA.","DOI":"10.1109\/VTCFall.2015.7390857"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Li, G., Hu, A., Sun, C., and Zhang, J. (2018). Constructing Reciprocal Channel Coefficients for Secret Key Generation in FDD Systems. IEEE Commun. Lett.","DOI":"10.1109\/LCOMM.2018.2875708"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Peng, L., Li, G., Zhang, J., Woods, R., Liu, M., and Hu, A. (2018). An Investigation of Using Loop-back Mechanism for Channel Reciprocity Enhancement in Secret Key Generation. IEEE Trans. Mob. Comput.","DOI":"10.1109\/TMC.2018.2842215"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Kreiser, D., Dyka, Z., Kornemann, S., Wittke, C., Kabin, I., Stecklina, O., and Langendoerfer, P. (2017). On Wireless Channel Parameters for Key Generation in Industrial Environments. IEEE Access.","DOI":"10.1109\/ACCESS.2017.2748182"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Van Torre, P. (2016). Channel-Based Key Generation for Encrypted Body-Worn Wireless Sensor Networks. Sensors, 16.","DOI":"10.3390\/s16091453"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Yuliana, M. (2017, January 16\u201318). Performance evaluation of the key extraction schemes in wireless indoor environment. In Proceedings of the International Conference on Signals and Systems (ICSigSys), Sanur, Indonesia.","DOI":"10.1109\/ICSIGSYS.2017.7967029"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Castel, T., Van Torre, P., and Rogier, H. (2016, January 23\u201324). RSS-based secret key generation for indoor and outdoor WBANs using on-body sensor nodes. Proceedings of the International Conference on Military Communications and Information Systems (ICMCIS), Brussels, Belgium.","DOI":"10.1109\/ICMCIS.2016.7496540"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1484","DOI":"10.1109\/TIFS.2012.2206385","article-title":"Exploiting Channel Diversity in Secret Key Generation from Multipath Fading Randomness","volume":"7","author":"Liu","year":"2012","journal-title":"IEEE Trans. Inf. Forensics Secur."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Marino, F., Paolini, E., and Chiani, M. (2014, January 1\u20133). Secret key extraction from a UWB channel: Analysis in a real environment. Proceedings of the IEEE International Conference on Ultra-WideBand (ICUWB), Paris, France.","DOI":"10.1109\/ICUWB.2014.6958955"},{"key":"ref_32","first-page":"1","article-title":"Efficient Physical-Layer Secret Key Generation and Authentication Schemes Based on Wireless Channel-Phase","volume":"2017","author":"Cheng","year":"2017","journal-title":"Mob. Inf. Syst."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Jiang, Y., Hu, A., and Huang, J. (2018). A lightweight physical-layer based security strategy for Internet of things. Clust. Comput.","DOI":"10.1007\/s10586-018-1820-0"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Ambekar, A., Hassan, M., and Schotten, H.D. (2012, January 3\u20135). Improving channel reciprocity for effective key management systems. Proceedings of the International Symposium on Signals, Systems and Electronics (ISSSE), Postdam, Germany.","DOI":"10.1109\/ISSSE.2012.6374318"},{"key":"ref_35","first-page":"2701","article-title":"Efficient key generation leveraging wireless channel reciprocity and discrete cosine transform","volume":"11","author":"Zhan","year":"2017","journal-title":"KSII Trans. Internet Inf. Syst."},{"key":"ref_36","first-page":"474","article-title":"Performance Improvement of Secret Key Generation Scheme in Wireless Indoor Environment","volume":"9","author":"Yuliana","year":"2017","journal-title":"Int. J. Comm. Netw. Inf. Secur."},{"key":"ref_37","unstructured":"Ambekar, A., Kuruvatti, N., and Schotten, H.D. (2012, January 11\u201313). Improved method of secret key generation based on variations in wireless channel. Proceedings of the International Conference on Systems, Signals and Image Processing (IWSSIP), Vienna, Austria."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.jnca.2017.11.014","article-title":"Efficient key generation leveraging wireless channel reciprocity for MANETs","volume":"103","author":"Zhan","year":"2018","journal-title":"J. Netw. Comput. Appl."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"McGuire, M. (2014, January 13\u201316). Channel Estimation for Secret Key Generation. Proceedings of the International Conference on Advanced Information Networking and Applications, Victoria, BC, Canada.","DOI":"10.1109\/AINA.2014.60"},{"key":"ref_40","unstructured":"Zenger, C.T. (2017). Physical\u2013Layer Security for the Internet of Things. [Ph.D. Thesis, Ruhr-University Bochum]."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1016\/0022-0000(79)90044-8","article-title":"Universal Classes of Hash Functions","volume":"18","author":"Carter","year":"1979","journal-title":"J. Comput. Syst. Sci."},{"key":"ref_42","first-page":"100","article-title":"Archived Publication Secure Hash Standard","volume":"2","author":"Publication","year":"1987","journal-title":"Public Law"},{"key":"ref_43","unstructured":"Zhao, J., Xi, W., Han, J., Tang, S., Li, X., Liu, Y., Gong, Y., and Zhou, Z. (arXiv, 2012). Efficient and Secure Key Extraction using CSI without Chasing down Errors, arXiv."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2763","DOI":"10.1109\/TMC.2013.71","article-title":"Eliminating reconciliation cost in secret key generation for body-worn health monitoring devices","volume":"13","author":"Ali","year":"2014","journal-title":"IEEE Trans. Mob. Comput."},{"key":"ref_45","unstructured":"Moore, T. (2001). IEEE 802.11-01\/610r02: 802.1.x and 802.11 Key Interactions, Microsoft Research. Technical Report."},{"key":"ref_46","unstructured":"NIST (2019, January 08). A Statistical Test Suite for Random and Pseudorandom Number Generators for Cryptographic Applications, Available online: http:\/\/csrc.nist.gov\/publications\/nistpubs\/800-22\/sp-800-22-051501."},{"key":"ref_47","unstructured":"Lopez, A.B. (2017). Physical Layer Key Generation for Wireless Communication Security in Automotive Cyber-Physical Systems. [Ph.D. Thesis, University of California]."},{"key":"ref_48","unstructured":"Ambekar, A. (2015). Exploiting Radio Channel Aware Physical Layer Concepts. [Ph.D. Thesis, Ruhr-University Bochum]."},{"key":"ref_49","unstructured":"Kai, Z., Wu, D., An, C., and Mohapatra, P. (2010, January 14\u201319). Exploiting Multiple-Antenna Diversity for Shared Secret Key Generation in Wireless Networks. Proceedings of the International Conference on IEEE INFOCOM, San Diego, CA, USA."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"917","DOI":"10.1109\/TMC.2012.63","article-title":"Secret key extraction from wireless signal strength in real environments","volume":"12","author":"Premnath","year":"2013","journal-title":"IEEE Trans. Mob. Comput."}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/21\/2\/192\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:32:59Z","timestamp":1760185979000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/21\/2\/192"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,2,18]]},"references-count":50,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2019,2]]}},"alternative-id":["e21020192"],"URL":"https:\/\/doi.org\/10.3390\/e21020192","relation":{},"ISSN":["1099-4300"],"issn-type":[{"value":"1099-4300","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,2,18]]}}}