BoxLock: Mobile-based Serpent cryptographic algorithm and One-Time Password mechanism implementation for Dropbox files security

Dropbox, a popular cloud storage provider, pose several threats especially in terms of file security and unauthorized access. An Android and a web application which implemented Serpent cryptographic algorithm and One-Time Password (OTP) mechanism to secure files on Dropbox and a web application was built as a solution by utilizing Dropbox Application Programming Interface (API) and Bouncy Castle library. The aim of this research is to make an application for encrypting Dropbox files and therefore, to ensure uploaded files from being accessed by unauthorized parties. In this research, Serpent algorithm was implemented because of its hardware efficiency and an additional feature, OTP mechanism, was used as additional user authentication process. The research shown that encryption and decryption processes each took three seconds for processing a two megabytes file, and the file was not accessible in encrypted form.