Twisting Lattice and Graph Techniques to Compress Transactional Ledgers

Abstract

Keeping track of financial transactions (e.g., in banks and blockchains) means keeping track of an ever-increasing list of exchanges between accounts. In fact, many of these transactions can be safely "forgotten", in the sense that purging a set of them that compensate each other does not impact the network's semantic meaning (e.g., the accounts' balances). We call nilcatenation a collection of transactions having no effect on a network's semantics. Such exchanges may be archived and removed, yielding a smaller, but equivalent ledger. Motivated by the computational and analytic benefits obtained from more compact representations of numerical data, we formalize the problem of finding nilcatenations, and propose detection methods based on graph and lattice-reduction techniques. Atop interesting applications of this work (e.g., decoupling of centralized and distributed databases), we also discuss the original idea of a "community-serving proof of work": finding nilcatenations constitutes a proof of useful work, as the periodic removal of nilcatenations reduces the transactional graph's size.

Blockchain Mutability: Challenges and Proposed Solutions

“…Pruning [55,85,86] Redactable blockchains Chameleon hash [79] Meta-transactions [99] Consensus-based Voting [100] Omit content of Transactions [76] Self-destruct/suicide Functions [104] Block matrix [101] Storage Immutability & the RtbF Fig. 2.…”

“…While originally pruning aimed at compressing the blockchain size on the assumption that historical data are not required, it is argued that it can also offer an increased level of user privacy since old transactions might not be locatable. Accordingly, it can serve regulatory requirements allowing the old transactions to be forgotten from the network [85], [55], [86]. In this respect, a cryptocurrency scheme called the "mini-blockchain" has been proposed as a pruning alternative to current blockchain implementations [87].…”

HyperBSA: A High-Performance Consortium Blockchain Storage Architecture for Massive Data

“…S. Nakamoto discussed a method of keeping the latest trading records by abandoning other executed transactions [12]. R. Géraud et al gave a solution based on graph algorithm and lattice reduction to compress transaction account ledger [6]. X. Chen proposed a method to replace the hash pointer with index pointer to reduce the storage space required by Bitcoin storage [13].…”

“…Most of them tried to reduce data storage volume rather than reforming the underlying architecture. Compressing node data [6] and processing data collaborative storage [7] are the two main kinds of ways to reduce the amount of data in blockchain nodes. However, reducing the amount of data excessively will lead to incomplete record in the blockchain, which is not a good idea.…”

The nilcatenation problem and its application for detecting money laundering activities in cryptocurrency networks

“…The nilcatenation problem (NCP) was introduced in Géraud et al. (2017) as a mechanism for compressing transactional graphs. In an arc‐weighted directed multigraph, the balance of a vertex is defined as the difference between the sum of the weights of the outgoing arcs and the sum of the weights of the incoming arcs.…”