The purpose of the VDI is to provide an infrastructure for data to be stored in a way that its presence, or lack thereof, can be cryptographically proven. It takes advantage of blockchain technology to determine the integrity of the data it contains.
The VDI component consists of a library that implements a Compact Sparse Merkle Tree (CSMT) and exposes an API that allows for data to be inserted, retrieved, updated and removed. The API consumer can later obtain proofs of membership/non-membership and verify those proofs against the existing Merkle tree.
This data structure works on the same principles of Verifiable Maps , periodically generating a root hash that, after been made public, can guarantee the integrity of the data at that point in time. Membership or non-membership of any given key can be cryptographically proven against the Merkle tree.