Creating Secure File Systems in Open-Source Operating Systems

Abstract

The relevance of this study is determined by insecure data storage on personal computers, as it is the main operating system that performs authentication and file access control. Bypassing these security rules is possible in case of using another open-source operating system on the same personal computer. The aim of this work is the research and development of file encryptors, disk encryptors and file system encryptors. Each of them has its shortcomings which manifest themselves during development. Combining the advantages of file encryptors and file system encryptors helped to overcome those shortcomings. The userspace filesystem library was used for this purpose. The study involved the methods aimed at designing and developing the Udev daemon file system for Linux using the OpenSSL library. The file system design was mathematically modelled and formally verified through a test parser. The file system also has its own authentication and authorization procedures to provide uniform access across multiple operating systems. The Udev daemon file system is the result of this work. Each file is encrypted with a separate key to protect against cryptanalysis. This key is encrypted with the owner’s private key, thereby enabling him/her to change the ownership. The passphrase is used to decrypt the user’s private key. The developed file system has passed authentication and access control testing successfully. The file system shows best performance with file sizes 1 KB to 256 MB. Encryption-caused performance degradation was also measured and found to be within acceptable limits. This Udev daemon stackable file system is available for all Unix clones with OpenSSL libraries. The prospects for further work are the development of a file system using several combined methods from a list of existing design and development methods for file systems.