Search efficient blockchain-based immutable logging and querying

Abstract

Blockchain offers the ability to create distributed databases that can be trusted, even if some actors on the network may be malicious. We consider the problem of reducing the read overhead of a ledger built using blockchains as part of the IDASH 2018 competition. In this scenario, we have multiple nodes granted to access a server. The goal is to store the activity logs of the nodes accessing the server in a secure fashion, using a blockchain-based ledger. To increase search speed, we propose splitting the ledger into groups based on expected search terms, and storing each group on a separate blockchain. By doing so, a search for all records of a specific type is transformed from a linear search on all records, to a linear search on a small subset of records. In our solution, this increases search efficiency by a factor of 8, at the cost of increasing storage overhead by a factor of 4. The system can be adjusted based on what types of searches are expected to reduce this overhead.