Exclusion-intersection encryption

摘要

We propose a new variant of identity-based encryption named as exclusion-intersection encryption: Intersection decryption keys (e.g., A∩B∩C) generated by a key generation centre can only be used to decrypt the ciphertext which is of all the specified groups' interests, its holders are excluded from decrypting when the documents are not targeted to all these groups (e.g., the key of A∩B∩C cannot decrypt the ciphertext targeted only to C). While recent advances in cryptographic techniques can support a more general access control policy, the private key size is often not a constant. We also present an online/offline variant.