Compact Sparse Merkle Trees

Abstract

A Sparse Merkle tree is based on the idea of a complete Merkle tree of an intractable size. The assumption here is that as the size of the tree is intractable, there would only be a few leaf nodes with valid data blocks relative to the tree size, rendering the tree as sparse. We present a novel approach called Minimum distance path algorithm to simulate this Merkle tree of intractable size which gives us efficient space-time trade-offs. We provide the algorithms for insertion, deletion and (non -) membership proof for a leaf in this Compact Sparse Merkle tree.

DEFS—Data Exchange with Free Sample Protocol

“…A Merkle hash tree (MHT) is an authenticated data structure where every leaf node of the tree contains the cryptographic hash of a data block and every non-leaf node contains the concatenated hashes of its child nodes [7]. MHTs allow linking a set of data to a unique hash value, the Merkle hash tree root (MR), allowing efficient and secure verification of the consistency and content of large sets of data.…”

“…If the data portion d e does not start with the index e, the provider was cheating, so the transaction ends transferring the costs (p+collateral) to the consumer. (7) withdraw:…”