Combining ABCs with ABE: Privacy-Friendly Key Generation for Smart Card Based Attribute-Based Encryption

摘要: Attribute-Based Credential (ABC) schemes provide a privacy-friendly method to perform authentication. In such system the user does not necessarily have identify himself, but may reveal only partial information about him, i.e., attributes possesses. The use of this technique is proper solution for several kinds authentication where no full identification required, e.g., buying liquor at store or opening door an office building. However, using Encryption (ABE) provides some advantages ABCs in case data protection. Ciphertext-Policy ABE allow define access policy over encrypted file, so that individuals possessing right can decrypt file. The authorization takes place when tries file; involve on-line party as would be required by ABC system. A smart card implementation Identity Mixer (idemix) credentials exists, making it feasible implement system. Little progress has been made create scheme suitable run similar environment. Most require computationally complex decryption algorithms take too much time on current cards. Moreover, many multi-authority violate user’s privacy requiring his unique identifier, enabling authorities profile its users. We overview different types and describe terms security efficiency. Using our classification, we select Lewko–Waters decentralized adapt meet requirements. We propose Blind Key Generation protocol way do key issuance without having identifier. We prove secure against three attackers definitions introduced Green Hohenberger. Additionally, Off-card Decrypt protocol. This enables us outsource most operations trusted device, yet safely keys never them.