MSc IS Thesis Defense by POH Zhi Yuan | Attribute-Based Secure Messaging in the Cloud

Messaging systems operating in the public cloud are very popular today. However, designs of earlier messaging services like electronic mail (email) and Short Message Service (SMS) focus on functionalities over security. Messaging services lacking security features particularly, without end-to-end message encryption can reveal information to unauthorized users. Recent messaging systems like WhatsApp and Facebook Messenger use traditional public-key cryptography to provide end-to-end encryption for messages which pose concerns on scalability. Attribute-Based Encryption (ABE) is a promising technology which provide scalable end-to-end encryption for messaging services. ABE is a one-to-many public key encryption system which provides expressive and fine-grained access control based on user attributes. Data owner encrypts messages with access policies and only users with matching attributes can obtain original messages. This project focuses on designing an attribute-based messaging system which provide three key features: users can enforce expressive fine-grained access control of messages, outsourcing decryption to the cloud without compromising message confidentiality, and users can be effectively revoked with server-aided revocation. Prototypes demonstrate the feasibility of the proposed design of the messaging system. In addition, prototypes are implemented based on Lightweight Directory Access Protocol (LDAP) which is used to manage users and attributes. Performance evaluation of prototypes illustrate various trade-offs and considerations when implementing the system.

Poh Zhi Yuan is currently pursuing his MSc in the School of Information Systems (SIS) at SMU under the supervision of Professor Robert Deng. His research focuses on applied cryptography.