Indexing structures for the PLS blockchain

This paper studies known indexing structures from a new point of view: minimisation of data exchange between an IoT device acting as a blockchain client and the blockchain server running a protocol suite that includes two Guy Fawkes protocols, PLS and SLVP. The PLS blockchain is not a cryptocurrency instrument; it is an immutable ledger offering guaranteed non-repudiation to low-power clients without use of public key crypto. The novelty of the situation is in the fact that every PLS client has to obtain a proof of absence in all blocks of the chain to which its counterparty does not contribute, and we show that it is possible without traversing the block’s Merkle tree. We obtain weight statistics of a leaf path on a sparse Merkle tree theoretically, as our ground case. Using the theory we quantify the communication cost of a client interacting with the blockchain. We show that large savings can be achieved by providing a bitmap index of the tree compressed using Tunstall’s method. We further show that even in the case of correlated access, as in two IoT devices posting messages for each other in consecutive blocks, it is possible to prevent compression degradation by re-randomising the IDs using a pseudorandom bijective function. We propose a low-cost function of this kind and evaluate its quality by simulation, using the avalanche criterion.

A Review on Bitcoin and Currency Encryption

In today's world, security has become a major issue in our lives, and in this era, one cannot trust the government for handling their lifetime savings. That's where the bitcoin comes to our lives. In this chapter, the authors try to understand one of the famous innovative payment methods (Bitcoin), how it is used and the data structure (Merkle tree) that is used in it. Also, they discuss one of the most recent attacks that involved the use of bitcoin (Wanacry). Further, they try to understand how this hack succeeded in stealing 10,800 euros that is 8,74,290 rs from the hospital with the help of bitcoin. They also discuss the various bitcoin companies now emerging with their own security measures against such hacks.