An Efficient NIZK Scheme for Privacy-Preserving Transactions over Account-Model Blockchain

We introduce the abstract framework of decentralized smart contracts system with balance and transaction amount hiding property under the ACCOUNT architecture. To build a concrete system with such properties, we utilize a homomorphic public key encryption scheme and construct a highly efficient non-interactive zero knowledge (NIZK) argument based upon the encryption scheme to ensure the validity of the transactions. Our NIZK scheme is perfect zero knowledge in the common reference string model, while its soundness holds in the random oracle model. Compared to previous similar constructions, our proposed NIZK argument dramatically improves the time efficiency in generating a proof, at the cost of relatively longer proof size

A Secure and Efficient Authentication Scheme for Access Control in Mobile Pay-TV Systems

[[abstract]]Recently, Sun and Leu proposed an efficient authentication scheme for access control in mobile pay-TV systems based on pairing and elliptic curve cryptography. In Sun and Leu's scheme, there exist two fatal security flaws, including 1) failure in subscriber authentication and 2) vulnerable to unauthorized access, which contradict to the security claims of Sun and Leu's scheme. To meet the claimed security requirements, we strengthen Sun and Leu's scheme with only lightweight modifications.[[note]]SC