Biblio

Ciphertext policy attribute-based encryption (CP-ABE) is a promising cryptographic technology that provides fine-grained access control as well as data confidentiality. It enables one sender to encrypt the data for more receivers, and to specify a policy on who can decrypt the ciphertext using his/her attributes alone. However, most existing ABE schemes are constructed on bilinear maps and they cannot resist quantum attacks. In this paper, we propose a multi-authority CP-ABE (MA-CPABE) scheme on ideal lattices which is still secure in post-quantum era. On one hand, multiple attribute authorities are required when user's attributes cannot be managed by a central authority. On the other hand, compared with generic lattice, the ideal lattice has extra algebraic structure and can be used to construct more efficient cryptographic applications. By adding some virtual attributes for each authority, our scheme can support flexible threshold access policy. Security analysis shows that the proposed scheme is secure against chosen plaintext attack (CPA) in the standard model under the ring learning with errors (R-LWE) assumption.

Cryptographic hash functions play a crucial role in information security. Cryptographic hash functions are used in various cryptographic applications to verify the message authenticity and integrity. In this paper we propose a Cellular Automata Based Hashing Algorithm (CABHA) for generating strong cryptographic hash function. The proposed CABHA algorithm uses the cellular automata rules and a custom transformation function to create a strong hash from an input message and a key.

Cryptographic applications need high-quality random number generator (RNG) for strong security and privacy measures. This paper presents RNG based on a hydrogen gas sensor that is fabricated by using microfabrication techniques. The proposed approach extracts the thermal noise information as an entropy source from the gas sensor that is non-deterministic during its operation and using hash function SHA-256 as post processing. This non-deterministic noise is then processed to acquire a random number set fulfilling the NIST 800-22 statistical randomness test suite and it demonstrates that a gas sensor based RNG can provide high-quality random numbers. Secure data transfer is possible by having this method directly without any other hardware where hydrogen gas sensor needs to be used such as petrochemical field, fuel cells, and nuclear reactors.

Membership revocation is essential for cryptographic applications, from traditional PKIs to group signatures and anonymous credentials. Of the various solutions for the revocation problem that have been explored, dynamic accumulators are one of the most promising. We propose Braavos, a new, RSA-based, dynamic accumulator. It has optimal communication complexity and, when combined with efficient zero-knowledge proofs, provides an ideal solution for anonymous revocation. For the construction of Braavos we use a modular approach: we show how to build an accumulator with better functionality and security from accumulators with fewer features and weaker security guarantees. We then describe an anonymous revocation component (ARC) that can be instantiated using any dynamic accumulator. ARC can be added to any anonymous system, such as anonymous credentials or group signatures, in order to equip it with a revocation functionality. Finally, we implement ARC with Braavos and plug it into Idemix, the leading implementation of anonymous credentials. This work resolves, for the first time, the problem of practical revocation for anonymous credential systems.

We propose to use a genetic algorithm to evolve novel reconfigurable hardware to implement elliptic curve cryptographic combinational logic circuits. Elliptic curve cryptography offers high security-level with a short key length making it one of the most popular public-key cryptosystems. Furthermore, there are no known sub-exponential algorithms for solving the elliptic curve discrete logarithm problem. These advantages render elliptic curve cryptography attractive for incorporating in many future cryptographic applications and protocols. However, elliptic curve cryptography has proven to be vulnerable to non-invasive side-channel analysis attacks such as timing, power, visible light, electromagnetic, and acoustic analysis attacks. In this paper, we use a genetic algorithm to address this vulnerability by evolving combinational logic circuits that correctly implement elliptic curve cryptographic hardware that is also resistant to simple timing and power analysis attacks. Using a fitness function composed of multiple objectives - maximizing correctness, minimizing propagation delays and minimizing circuit size, we can generate correct combinational logic circuits resistant to non-invasive, side channel attacks. To the best of our knowledge, this is the first work to evolve a cryptography circuit using a genetic algorithm. We implement evolved circuits in hardware on a Xilinx Kintex-7 FPGA. Results reveal that the evolutionary algorithm can successfully generate correct, and side-channel resistant combinational circuits with negligible propagation delay.