Permissioned blockchains ensure integrity and auditability of shared data but expose query parameters to peers during read operations, creating privacy risks for organizations querying sensitive records. This paper proposes a Private Information Retrieval (PIR) mechanism to enable private reads from Hyperledger Fabric's world state, allowing endorsing peers to process encrypted queries without learning which record is accessed. We implement and benchmark a PIR-enabled chaincode that performs ciphertext-plaintext (ct-pt) homomorphic multiplication directly within evaluate transactions, preserving Fabric's endorsement and audit semantics. The prototype achieves an average end-to-end latency of 113 ms and a peer-side execution time below 42 ms, with approximately 2 MB of peer network traffic per private read in development mode--reducible by half under in-process deployment. Storage profiling across three channel configurations shows near-linear growth: block size increases from 77 kilobytes to 294 kilobytes and world-state from 112 kilobytes to 332 kilobytes as the ring dimension scales from 8,192 to 32,768 coefficients. Parameter analysis further indicates that ring size and record length jointly constrain packing capacity, supporting up to 512 records of 64 bytes each under the largest configuration. These results confirm the practicality of PIR-based private reads in Fabric for smaller, sensitive datasets and highlight future directions to optimize performance and scalability.

翻译：许可区块链确保了共享数据的完整性和可审计性，但在读取操作期间会将查询参数暴露给节点，为查询敏感记录的组织带来隐私风险。本文提出一种私有信息检索机制，以实现从Hyperledger Fabric世界状态中进行私有读取，允许背书节点处理加密查询而无需知晓具体访问的记录。我们实现并基准测试了一种支持PIR的链码，该链码在评估交易中直接执行密文-明文同态乘法，同时保留了Fabric的背书与审计语义。该原型在开发模式下平均端到端延迟为113毫秒，节点侧执行时间低于42毫秒，每次私有读取产生约2MB的节点网络流量——在进程内部署模式下可减少一半。对三种通道配置的存储分析显示近线性增长：当环维度从8,192个系数扩展至32,768个系数时，区块大小从77千字节增至294千字节，世界状态从112千字节增至332千字节。参数分析进一步表明环尺寸与记录长度共同制约打包容量，在最大配置下可支持512条64字节的记录。这些结果证实了基于PIR的私有读取在Fabric中处理较小规模敏感数据集的实用性，并为未来性能与可扩展性优化指明了方向。