Attribute-Based Encryption (ABE) allows to target the recipients of a message according to a policy expressed as a predicate among some attributes. Ciphertext-policy ABE schemes can choose the policy at the encryption time. In this paper, we define a new property for ABE: homomorphic-policy. A combiner is able to (publicly) combine ciphertexts under different policies into a ciphertext under a ...

In a group-oriented threshold cryptosystem, each group, instead of each individual member within the group, publishes a single group public key. An outsider can use this group public key to send encrypted messages to the group. However, the received encrypted messages can only be decrypted properly when the number of participating members is larger than or equal to the threshold value. All earl...

This issue of the journal is devoted to the themes of Geometry, Combinatorial Designs and Cryptology. The guest editors selected sixteen contributions covering various areas within these themes, ranging from public-key cryptography to matters related to key distribution and authentication, from problems in graph theory to resolvability issues in designs, from finite projective planes to higher-...

In today’s digital world, multimedia content is delivered to homes via the Internet, satellite, terrestrial and cable networks. Scrambling is a common approach used by conditional access systems to prevent unauthorized access to audio/visual data. The descrambling keys are securely distributed to the receivers in the same transmission channel. Their protection is an important part of the key ma...

We introduce the notion of predicate encodings, an information-theoretic primitive reminiscent of linear secret-sharing that in addition, satisfies a novel notion of reusability. Using this notion, we obtain a unifying framework for adaptively-secure public-index predicate encryption schemes for a large class of predicates. Our framework relies onWaters’ dual system encryption methodology (Cryp...

Quantum secret sharing (QSS), quantum secure direct communication, and quantum teleportation, which are all included under quantum key distribution, are used to share or distribute a secure key in a quantum environment. We emphasize cooperation between communicating parties to eliminate un-trustworthy members and to improve the strength of the key.

In the multiterminal secret key agreement problem, a set of users want to discuss with each other until they share a common secret key independent of their discussion. We want to characterize the maximum secret key rate, called the secrecy capacity, asymptotically when the total discussion rate goes to zero. In the case of only two users, the capacity is equal to the Gács–Körner common informat...

Visual Cryptography is a special type of encryption technique to obscure image-based secret information which can be decrypted by Human Visual System (HVS). It is a kind of secret-sharing scheme that encrypts the secret image into n number of shares. It is imperceptible to reveal the secret information unless a certain number of shares(k) or more are superimposed. As the decryption process is d...