A Flexible Network Approach to Privacy of Blockchain Transactions

For preserving privacy, blockchains can be equipped with dedicated mechanisms to anonymize participants. However, these mechanism often take only the abstraction layer of blockchains into account whereas observations of the underlying network traffic can reveal the originator of a transaction request. Previous solutions either provide topological privacy that can be broken by attackers controlling a large number of nodes, or offer strong and cryptographic privacy but are inefficient up to practical unusability. Further, there is no flexible way to trade privacy against efficiency to adjust to practical needs. We propose a novel approach that combines existing mechanisms to have quantifiable and adjustable cryptographic privacy which is further improved by augmented statistical measures that prevent frequent attacks with lower resources. This approach achieves flexibility for privacy and efficency requirements of different blockchain use cases.Comment: 6 pages, 2018 IEEE 38th International Conference on Distributed Computing Systems (ICDCS

Security and Privacy Using One-Round Zero-Knowledge Proofs

A zero-knowledge proof (ZKP) is an interactive proof that allows a prover to prove the knowledge of a secret to a verifier without revealing it. ZKPs are powerful tools to deal with critical applications in security e-commerce. Existing ZKPs are iterative in nature; their protocols require multiple communication rounds. The cost of iteration makes ZKPs unsuitable in practice. We propose a new protocol that meets all the requirements of ZKPs, yet runs in one round. The new approach substantially reduces computation and communications costs. It makes ZKPs more suitable for practical cryptographic systems for both govern-ment and commercial applications