Patent ID: 7831573

Claim:
A computer-implemented method of committing to a data set, comprising: forming, by said computer, a directed acyclic graph adapted to encode the data set, the directed acyclic graph having a plurality of pointers and a plurality of nodes wherein at least one node has multiple parents from the directed acyclic graph, the directed acyclic graph having at least one root node and a plurality of leaf nodes; committing to the directed acyclic graph to produce, by said computer, a committed-to data set; and producing, by said computer, a plurality of proofs about the committed-to data set such that a combination of the plurality of proofs does not reveal information about which nodes have multiple parents, each proof comprising a trace from one of the plurality of nodes to at least one different node, the trace comprising the identities of the nodes and pointers traversed, wherein producing a plurality of proofs comprises producing multiple proofs each showing that a different given element is not present in the committed-to data set and limiting a number of these proofs produced per committed-to data set.