International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 08 Issue: 03 | Mar 2021 www.irjet.net p-ISSN: 2395-0072 © 2021, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 294 Secure File Storage on Cloud using Enhanced Hybrid Cryptography Reece B. D’Souza 1 , Dr. Ruby D. 2 1 Student, School of Computer Science & Engineering, Vellore Institute of Technology, Tamil Nadu, India 2 Assistant Professor, School of Computer Science & Engineering, Vellore Institute of Technology, Tamil Nadu, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - In recent years ‘cloud’ has taken over the world, offering a new and dynamic form for computation and storage. Several corporations offer cloud services, for example, Amazon Web Services (AWS), Google Cloud Platform (GCP), Microsoft Azure, etc. These cloud services are cheaper in the long run and their services are highly efficient. But a lot of small-scale corporations do not switch to the cloud due to the lack of security associated with the cloud. Therefore, the paper presents a method of storing files in the cloud securely. With the use of modified hybrid encryption, the files stored in the cloud are secure. Accessing any files leaked from the cloud would be futile without the keys and real-time authentication service offered by the model presented in the paper. The model uses the AES algorithm enhanced by threads and RSA Signing and Verification algorithm, along with a real-time OTP generation service to provide high security. While encrypting the file using AES, a key is entered and the file is split into eight pieces and encrypted simultaneously stored in a zip folder on the cloud. While requesting to download a file, the necessary key needs to be entered and an OTP will be emailed to the registered email which needs to be entered. Decryption works in the exact reverse of encryption. Thus, the model offers safe and secure encryption of files and storage in the cloud. Key Words: CSPs (Cloud Service Providers), Encryption, Decryption, AES (Advanced Encryption Standard), RSA (Rivest–Shamir–Adleman), OTP (One Time Passwords). 1. INTRODUCTION Cloud computing is a subscription-based or pay-per-use service that extends an IT company’s capability, especially when used in real-time. With the introduction of cloud computing in the early 2000s, there was a significant change in not only the software but other fields as well. Hardware and software are generally used for heavy computation, but now with cloud computing, this load is lifted as the cloud handles it instead. Cloud computing can be defined as a type of computing that shares computing resources over a network rather than having local or personal servers to handle computation. In a more technical aspect, it is the use of remote servers to store, manage, and process data rather than achieve the same on a local server or a personal computer [1]. Cloud computing offers a variety of different services – such as servers, storage, and computations – which are delivered to the client over the internet. Cloud applications are developed in Platforms as a Service following the PaaS architecture imposed by several providers [1]. Several companies in the world offer these cloud services. They are called ‘Cloud Service Providers’ or ‘CSPs’ in short. These companies offer network services, business applications, or even infrastructure in the cloud. The large benefit of using these services via these companies is it is highly efficient when used economically. Rather than maintaining the individual infrastructure of the company, outsourcing these services to third parties for a reasonable price is highly efficient. The focus of this paper is one of these services, namely storage and more importantly its security. With the introduction of cloud computing, the use of traditional storage devices is declining. This is because, with the help of the cloud, information is stored in a centralized environment accessible from any part of the world having a viable internet connection. Cloud storage is useful because it eliminates the need for carrying physical storage devices and provides safe backups, while physical devices can be corrupted in some form, leading to loss of the entire data. Even though cloud storage has a higher form of safety over physical devices, it is not completely invulnerable. There have been several cases of data leakage from the cloud through the means of hacking or breaking into the cloud to steal valuable confidential company data for the benefit of the hacker. Even with the availability of data in the cloud, exposing them to applications that may already have security loopholes in them is extremely dangerous [2]. Therefore, storing information on the cloud will simply not suffice. Most businesses have avoided the use of CSPs for the very same reason. There are several methods for securing rough data sets such as the Genetic Algorithm (GA), K Mean Algorithm, KNN (K-Nearest Neighbour) Algorithm, and even Native Bayesian Technique [3]. But since data can be stored in any format in the cloud the use of cryptography would be beneficial. Through the use of cryptography, data can be safely stored. Even though the files are leaked, the files cannot be used as they are encrypted. Cryptography adds another layer to the security of the cloud. Earlier cryptography was only used for military or diplomatic communication up until the development of public-key cryptography. Cryptography can be defined as a system that through the use of some mathematical algorithm, transforms a sequence of characters that are fed to it [4]. This system is based on the value of a secret key, which is a parameter in the encryption as well as the decryption