Encrypted E-Mails with Practical Forward Secrecy

Abstract: Cloud computing may be a general term that involves delivering hosted services over the world wide web. These services are divided into three main categories: infrastructure as a service (IaaS), platform as a service (PaaS) and software as a service (SaaS). Cloud infrastructure involves hardware and software components for proper implementation of a model. Cloud computing can be thought of as utility computing or on-demand computing. Cloud computing works by enabling client devices to access data and cloud applications over the web from remote physical servers, databases and computers. With the widespread use of cloud emails and frequent reports on email leakage events, a security property called forward secrecy becomes desirable for both individuals and cloud email service providers to strengthen the protection of cloud email systems. Specifically, forward secrecy can guarantee the confidentiality of these previously encrypted emails whether or not the user’s secret key gets exposed. However, thanks to the failure to satisfy the protection requirements of email systems simultaneously, typical methods like Diffie-Hellman key exchange and forward-secure public-key encryption, haven't been widely approved and adopted. To capture forward secrecy of encrypted cloud email systems, we introduced a replacement cryptographic primitive called forward-secure puncture able identity-based encryption (fs-PIBE), which enables the user to perform fine-grained revocation of decryption capacity. in additional detail, the user is allowed to preserve the decryption capacity of unreceived encrypted emails while abolishing that of these received ones. Thus, it provides more practical forward secrecy than typical manners, during which the decryption capacity of received and unreceived encrypted emails is revoked simultaneously. supported such a primitive, we build a framework of encrypted cloud email systems.

Keywords: cloud emails, Forward secrecy, Diffie-Hellman, forward-secure public-key encryption, identity-based encryption, fs-PIBE.