PRIBANI: a privacy-ensured framework for blockchain transactions with information retrieval

The advent of blockchain technology has revolutionized Internet-of-Thing (IoT) systems offering immutable and transparent ledger mechanisms. However, this transformative technology has also brought significant challenges related to user privacy. Though the existing solutions offer various privacy enrichment in blockchain systems through cryptographic methods, the problems of deanonymization (the issue of revealing users' identities) and linkability of transactions still persist. Furthermore, recent reported news also shows privacy leakages in blockchain systems. Thus, we require a comprehensive privacy-assured blockchain framework to address the above-mentioned problems. In this paper, we introduce a novel privacy-preserving framework for blockchain transactions along with private information retrieval (PIR) to combat the above-mentioned privacy issues in blockchains. We call our proposed approach "PRIvacy-ensured framework for Blockchain trANsactions with pIr (PRIBANI)". PRIBANI uses randomizing ring signatures, Public key Encryption-based Keyword Search (PEKS), and PIR techniques to protect the privacy of the user and the history of the transaction data. We run a set of experiments on our proposed PRIBANI to evaluate the privacy attainment of the framework based on user anonymity, transaction anonymity, and unlinkability. We also compare PRIBANI with state-of-the-art models and show that PRIBANI gives a better throughput with an average of 56 transactions per second (TPS) and incurs low latency which is approximately 5% less than the existing schemes and an average communication overhead of 3.2 kilobytes (kbytes). Overall, PRIBANI is efficient in executing privacy-ensured blockchain transactions.