A secure DHT-based key distribution system for attribute-based encryption and decryption

Today, sharing information is ubiquitous in a connected world. However, several disadvantages exist, such as the loss of control over data or unwanted data processing and analysis by providers. A central data storage, which is applied by Online Social Networks (OSN), such as Facebook or driven by the government, such as storing medical health data of citizens centrally, is likewise affected. Efforts to store citizens' medical data centrally, driven by political, economic or IT-security reasons, bear the risk of data leakage. We envision a decentralized and data-owner-centric system, capable to support secure data sharing within private or business driven scenarios. A central aspect is to increase management capabilities, such as revocation for the data to be shared, while supporting fine grained access policies provided by Attribute-based Encryption (ABE). In this paper we introduce the Entrance system architecture, requirements and basic use-cases before we reach our main contribution: we discuss challenges and provide solutions arising from applying a Distributed Hash Table (DHT) for an Attribute-based Encryption (ABE) key distribution. We present algorithms for an enhanced encryption and decryption, and introduce the property of Ciphertext Expiration.