Recent years have witnessed the trend of leveraging cloudbased services for large scale content storage, processing, and distribution. Security and privacy are among top concerns for the public cloud environments. Towards end-toend content security, we propose and implement CloudSeal, a scheme for securely sharing and distributing content via the public cloud. CloudSeal ensures the confidentiality of content in the public cloud environments with flexible access control policies for subscribers and efficient content distribution via content delivery network. CloudSeal seamlessly integrates symmetric encryption, proxy-based re-encryption, k-out-of-n secret sharing, and broadcast revocation mechanisms. These algorithms allow CloudSeal to cache the major part of a stored cipher content object in the delivery network for content distribution, while keeping the minor part in the cloud storage for key management. The separation of subscription-based key management and confidentiality-orie...