Abstract: Techniques utilizing common encryption approaches for data from multiple parties enable those parties to discover information that is held in common by the parties without disclosing to any party information that is not held in common by the parties. Encrypted information for each party can be compared to determine which encrypted values match, and those encrypted values can be returned to any of the parties such that a party can determine which corresponding data the parties have in common, without having access to any other data of any other parties.