Abstract: Pseudorandom numbers may be generated from input seeds using expander graphs. Expander graphs are a collection of vertices that are interconnected via edges. Generally, a walk around an expander graph is determined responsive to an input seed, and a pseudorandom number is produced based on vertex names. Specifically, a next edge, which is one of multiple edges emanating from a current vertex, is selected responsive to an extracted seed chunk. The next edge is traversed to reach a next vertex. The name of the next vertex is ascertained and used as a portion of the pseudorandom number being produced by the walk around the expander graph.

Abstract: Function properties may be approximated using an expander graph. For example, an approximate average of a function may be determined by randomly exploring an expander graph. Values of the function are associated with vertices of the expander graph. The expander graph is randomly explored by traversing edges and encountering vertices. The exploration may comprise a crawl, a walk, and so forth. An approximate average of the function is determined based on the function values that are associated with encountered vertices.

Abstract: Hash function constructions from expander graphs are described. In one aspect, an expander graph is walked to compute a hash function. The expander graph is walked using respective subsets of an input message. A label of a last vertex walked is an output of the hash function.