The Repository @ St. Cloud State

Open Access Knowledge and Scholarship

Date of Award


Culminating Project Type

Starred Paper

Degree Name

Information Assurance: M.S.


Information Assurance and Information Systems


Herberger School of Business

First Advisor

Jim Q Chen

Second Advisor

Denis Guster

Third Advisor

Balasubramaniam Kasi

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.


Sharing data with peers is an important functionality in cloud storage. This is a study and analysis of secure, efficient, and flexible sharing of data with other users in cloud storage. The new public key encryptions which produce constant-size ciphertexts in such a way that effective delegation of decryption rights given to any set of ciphertexts are described in this paper. The novelty of the mechanism is that someone can aggregate any number of secret keys and turn them into a small single key, but combine the power of all the keys being grouped. To describe, in other words, the secret key holder could release a constant-size aggregate key for more flexible choices of ciphertext set in cloud storage, but different encrypted files outside of the set remain confidential. The aggregate compact key can be sent to others with ease or saved in a smart card with very less secure storage. In this paper, we discuss various such mechanisms and demonstrate the topic with a project. Some of the papers written by other authors in the area are analyzed in this paper. The project in this paper is a partial implementation of the proposed Crypto System.