Attribute-Based Encryption (ABE) is a promising cryptographic primitive which significantly enhances the versatility of access control mechanisms. Due to the high expressiveness of ABE policies, the computational complexities of ABE key-issuing (by Attribute Authorities (AAs)) and decryption (by eligible users) are getting prohibitively high. Despite that the existing Outsourced ABE solutions a...

The advent of new cryptographic methods in recent years also includes schemes related to functional encryption. Within these schemes Attribute-based Encryption (ABE) became the most popular, including ciphertext-policy and key-policy ABE. ABE and related schemes are widely discussed within the mathematical community. Unfortunately, there are only a few implementations circulating within the com...

In (key-policy) attribute based encryption (ABE), messages are encrypted respective to attributes x, and keys are generated respective to policy functions f . The ciphertext is decryptable by a key only if f(x) = 0. Adding homomorphic capabilities to ABE is a long standing open problem, with current techniques only allowing compact homomorphic evaluation on ciphertext respective to the same x. ...

Attribute-based encryption (ABE) is an exciting alternative to public-key encryption, as ABE develops encryption systems with high expressiveness, without the need for a public key infrastructure (PKI) that makes publicly available the mapping between identities (sets of attributes), public keys, and validity of the latter. Any setting, PKI or attribute-based, must provide a means to revoke use...

Our new Access Control Encryption is an implementation of CP-ABE, when used as part of a key delivery mechanism for an encrypted Data Base. It focuses on improving performance. In ACE the access policies are any predicates over the set of object attributes. E¢ ciency gains are most pronounced when the DNF representations of policies are compact. In ACE, within the life span of the keys, each us...

Attribute-based encryption (ABE) is a type of public key encryption that allows users to encrypt and decrypt messages based on user attributes. For instance, one can encrypt a message to any user satisfying the boolean formula (“crypto conference attendee” AND “PhD student”) OR “IACR member”. One drawback is that encryption and key generation computational costs scale with the complexity of the...

The notion of multi-authority attribute based encryption was introduced by Chase in TCC 2007. In this paper, we improve Chase’s scheme to allow encryptors to determine how many attributes are required for each ciphertext from related attribute authorities. The proposed scheme can be seen as a multi-trapdoor construction. Furthermore, we apply the LMSSS to outsource the decryption of multi-autho...

A revocable-storage attribute-based encryption (RS-ABE) scheme is an encryption scheme which extends attribute-based encryption by introducing user revocation. A key-policy RS-ABE scheme links each key to an access structure. We propose a new key-policy RS-ABE scheme whose security we prove in term of indistinguishability under a chosen-plaintext attack (IND-CPA).